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R142 Equipment and Materials for Environmental Monitoring. (03/09)

1. Operation continued Sensors are easily connected via leads and are instantly recognised by the logger Sciencescope sensors or Philip Harris SensorMeters or Firstsense sensors can be used Several parameters can be tracked at the same time The menu offers continuous autologging triggered logging fast recording or snapshot logging The start button operates logging that can be tracked by a meter on a LCD display on screen Up to four channels of sensor values may be displayed at once Snapshot mode allows sensor readings to be captured on demand and now the data is readily stored in the memory files For normal remote logging operations the maximum sample rate is 8 per second and logging will continue for over 40 days unless stopped In snapshot remote mode readings can be taken at any time Display on the ML shows values on screen in Sl units Display on the GL can be graphical and meter display Data may be tabulated analysed and graphically displayed after transfer to a PC using the Multilab software Analysis tools then include graphing gradients differences area etc It proved straightforward to modify the table of data and to add notes on activities via the keyboard Sciencescope also makes other versions of the Logbook logger These include the GL which has an option of Bluetooth wireless connection SE and XD The UL and WL models have essentially been replaced by the GL There is also a Logbook Primary
2. Memory Not relevant Screen size It has no screen 2 3 Carry case Comes with a hard carry case Top vertical face USB port Ports Bottom vertical face 3 large DIN ports for sensors Battery No battery required Wireless connection Not relevant Manual Comes with a guide including suggested activities Weather proofing No datalogger is waterproof Field use The Black Box is designed as an interface and because it has no internal power source it can only be used with a computer and not as a stand alone instrument It is more appropriate for laboratory use since it would need a computer to operate in the field Operation This is simply an interface and must be used to link sensors with a computer It cannot be used as a stand alone instrument Installation of the USB driver from CD supplied before charging is easy and quick Sensors were easily connected via leads and were auto recognised by the logger showing by one of three different coloured LEDs The software enabled control of the sensors from the computer and offered four levels of operation Secondary pupils are most likely to use the advanced level The data was automatically transferred to the computer and using the logIT software was analysed and presented in required graphical or other format Costs Supplier Catalogue number Price Griffin Education Black Box interface CRD 960 010W 85 00 Griffin Educat
3. that is packages with a logger and certain sensors at somewhat reduced rates These may be helpful provided that all of the items are ones that the school needs 61 8 7 3 Fourier Multilab software Compatibility Mainly compatible with Windows XP but may work with 98 and 2000 but not at present with VISTA Licence Various licences are available and can be arranged to suit school requirements Installation and operation The Quickstart guides provided did not make clear how the connection to a PC could be easily achieved The Nova web site provided some help but did not make clear that the Nova 5000 drivers must be downloaded first Once this had been done the connection was effective and environmental investigations could be readily controlled via the PC and downloaded data could be analysed as easily as on the Nova direct The opening screen as usual offered the same range of icons as those on the Nova As before the sensors were instantly recognised on screen The menu offered the same range of continuous logging individual readings e g at specific events or snapshot logging The start button operated logging which was tracked on screen The graph autoscaled on both axes where necessary to accommodate the data collected Several runs were collected and displayed together Snapshot mode allowed sensor readings to be captured on demand and the data readily stored As before there is a default sett
4. Ports Top vertical face 4 sensor ports and USBs for Windows amp Mac and printer Left hand vertical face audio in out and power jack sockets Right hand vertical face 2 sensor ports Built in microphone Battery Rechargeable lithium ion battery pack Charging is either from the mains or when connected to computer The battery should last at least a day in field use though this depends on which sensors are being used Wireless connection No wireless facility yet but Vernier is working on Bluetooth capability Licence No licence is needed for Labquest Manual This comes with a Quick start guide giving clear instructions on using the Labquest as a stand alone device or linked to a computer Upgrades Software can be upgraded on line from Vernier or IDS website Weather proofing The Labquest is shock resistant and shower proof but not to full immersion In the field users are still advised to store in a waterproof cover such as a plastic box Field use The small size and modest weight make this relatively easy to use in the field 42 Operation This neat datalogger can be used a stand alone device to record analyse and display data or as an interface to another computer Installation of the USB driver from CD supplied before charging is easy and quick There is a built in temperature sensor giving ambient temperature readings and a built in microphone and sound
5. 175 00 Data Harvest Easy Sense Q5 5025 209 00 Scientific amp Chemical Easy Sense Advanced DAT 051 010 229 Scientific amp Chemical Easy Sense Advanced DAT 051 020 255 Bluetooth enabled The Consortium Easy Sense Q3 310026 188 95 TTS Easy Sense Q3 849 ISENSE 189 00 8 2 2 Data Harvest Smart Q sensors Environmental Parameter Comment Air pressure The 3140 measures pressure in kPa range 0 to 110 kPa or in Hg 0 to 33 in Hg Tested results matched to other pressure readings with suitable accuracy Also acts as an altimeter with a range of 500 m to 12 000 m This was not tested Carbon dioxide The 3152 has a flat cylindrical shape thus facilitating formation of a sealed chamber with e g a beaker It covers two concentration ranges 0 to 10 000 PPM and 0 to 100 000 PPM The sensor responded quickly and gave sensible figures that reflected typical expected ranges though precise absolute values are difficult to confirm Colorimeter The 3275 offers two ranges 0 to 100 transmission and 0 05 to 1 05 absorption Red green yellow and blue slides and a pack of cuvettes are provided The tests carried out involved changes in opacity as might be found comparing turbidity in water samples Results were much in line with those expected As with many of the sensors there is a much wider range of uses in scientific investigations e g quantitative analysis of sugars enzyme reactions etc Cond
6. Snapshot mode allows sensor readings to be captured on demand and now the data is readily stored in the memory Scrolling allows a comment to be added and it was easy to repeat the experiment and identify each run separately It was also easy to retrieve data In easy log mode it was possible to permit logging of the desired sensor readings to continue indefinitely Default sampling is 40 readings per second for 1000 samples after which the sampling rate halves and every other sample is discarded This process is repeated indefinitely In logging mode the duration of logging the frequency and any desired triggers were easily set Changing these settings to suit the investigation proved to be straightforward Time amp motion mode was not tested but is likely to be of value when using light gates for example Data may be saved to a separate computer using the Easy sense software 26 Data Harvest also produces the Easy Sense Q3 and Q5 which have respectively three and five in built sensors and two sensor ports The Q3 is more suited to upper primary classes and the Q5 to upper primary classes middle schools and lower secondary classes They are cheaper at around 200 Costs Supplier Catalogue number Price Commotion Easy Sense Q3 13202 21 189 00 Data Harvest Easy Sense Q Advanced 4000 229 Data Harvest Easy Sense Q Advanced 4001 258 Bluetooth enabled Data Harvest Easy Sense Q3 5001
7. circumstances 30 8 3 DCP LoglT 8 3 1 DCP Log IT Datavision BX and CX Width 195 mm Height 108 mm Depth 52 mm at top 25 mm at bottom Weight 519g Memory 20 000 data points per sensor in 50 files Screen size 59mm by 41mm The small but clear screen somewhat limits the amount of information displayed Carry case Comes with a hard carry case Ports Top vertical face power socket 6 large DIN ports for sensors Left hand vertical face serial port and USB socket Battery Rechargeable NiMH battery Charging is either from mains or when connected to computer Charging should ideally be in excess of 24 hours Batteries should have a life of about a year with normal usage The battery should last up to 8 hours in field use longer if allowed to sleep in remote logging though this depends on which sensors are being used Wireless connection It has no wireless facility as standard but a Bluetooth option is available and is plugged in to the serial port Manual Comes with straightforward getting started guide Upgrades Software updates available from the website Weather proofing No datalogger is waterproof In the field users are advised to store in a waterproof cover such as a plastic or other box or to use the box provided Field use The size and weight make it less easy than some loggers to carry round in the field although a carry case hel
8. 00 Electrode Data Harvest 3136 29 00 Scientific amp Chemical DAT 060 750 29 00 Light normal Data Harvest 3120 26 00 Scientific amp Chemical DAT 060 540 26 00 Outdoor use Data Harvest 3122 26 00 Scientific amp Chemical DAT 060 560 26 00 Oxygen adapter Data Harvest 3130 39 00 Scientific amp Chemical DAT 060 610 39 00 Data Harvest 3131 89 00 electrode Scientific amp Chemical DAT 060 600 86 00 pH electrode Data Harvest 2251 29 00 Scientific amp Chemical DAT 060 570 29 00 electrode low conductivity Data Harvest 2252 69 00 Scientific amp Chemical DAT 060 580 59 00 Data Harvest 3125 34 00 adapter Scientific amp Chemical DAT 060 590 34 00 Relative humidity Data Harvest 3145 59 00 Scientific amp Chemical DAT 060 710 59 00 Sound Data Harvest 3175 49 00 Scientific amp Chemical DAT 060 700 49 00 Temperature Data Harvest 3100 29 00 Scientific amp Chemical DAT 060 500 29 00 Data Harvest 3101 29 00 Scientific amp Chemical DAT 060 500 29 00 Ultra violet Data Harvest 3277 59 00 Scientific amp Chemical DAT 060 910 59 00 There are a number of other sensors for the logger but they are not relevant to a study of environmental factors but the full range should be taken into account when deciding about which logger and which sensors to buy 8 2 3 DataHarvest software Compatibility Windows XP and VISTA Licence Easy Sense Advanced comes with multi use
9. However field use becomes far more limited with the necessity to carry the computer to all locations where investigations are to take place The logistics would also preclude the majority of remote logging investigations Costs Item Supplier Catalogue number Cost XLlogger software ITEC XLC2001 295 00 including school site licence 495 00 for FHE Institution XLlogger USB 4 port hub ITEC XLC6001 15 44 63 8 8 2 ITEC XLlogger software Compatibility The guidance leaflet indicates that the software works with any version of Excel that may be on the PC laptop or mini notebook being used In practice it seems to operate for any Excel version from 2000 onwards In order to ensure that it works with VISTA the directions given on the CD ROM must be followed exactly and security disabled Installation The fact that with an appropriate version of Excel no logger or other instrumentation and operation is required is an advantage Familiarity with Excel and its operation or more explicit guidance notes would be a considerable advantage Once installed a set of Quick start instructions may be downloaded It would be advantageous for these to have been available in hard copy prior to installation When a sensor is connected the software automatically installs the appropriate drivers and there is on screen recognition of the sensor which is then ready for use Once access to the software has been ac
10. a choice of presentation styles including real time graphs bar variation charts digital display or tabulated results It is also possible to have all four displayed at once using a split screen system This has some advantages but tended to make the screen appear over busy Data manipulation facilities included overlaying several runs graph zooms best fit data smoothing measurement of gradient and area under the graph s curve differentiation and integration Enhancement of presentation of graphs to include headers table graph description labels etc was also available and easy to use It proved easy to print to a standard printer It proved easy to fetch data from previous runs that had been captured in a logger and then to adjust the format and presentation of this data Data may be copied to Excel or Inspire and the system is compatible with Insight systems There is a booklet of suggested experiments some of which have an environmental theme These are not very prescriptive and could be used as a starting point for teachers to modify and adapt to their own pupils needs and circumstances 41 8 4 Vernier Labquest 8 4 1 Vernier Labquest Width 103 mm at top 78 mm at bottom Height 165 mm Depth 37 mm at top 18 mm at bottom Weight 354 g Memory 40 Mb can be extended via a SD MMC card or USB stick Screen size 74mm by 55mm Carry case No carry case is available yet
11. and scrolling was also subject to very slight delays Costs Supplier Catalogue number Price Philip Harris B8L 11239 342 50 23 8 1 3 Harris SensorMeters Philip Harris still produces its SensorMeter devices that have direct digital readouts These can be used as stand alone SensorMeters or in conjunction with e log II dataloggers which recognise the Firstsense and SensorMeter ranges This enables results from these machines to be recorded displayed and stored in a variety of ways 8 1 4 Harris sensors e log sensors are common to both e log Il dataloggers and are essentially designed ultimately to supersede Firstsense sensors Older Harris sensors including existing sensor meters can be used with the aid of an adapter examples suitable for environmental monitoring include conductivity dissolved oxygen ultraviolet and possibly high temperatures This could be useful to schools already possessing such meters especially since the range of e log sensors is rather more restricted at present than from some other suppliers Environmental Parameter Comment Air pressure This sensor measures air pressures in the range 850 to 1150 mB at sea level It has a satisfactory response time It can also be used to measure water pressure down to a depth of about 1 m Light Measures on a 0 to 100 scale rather than lux A collimating device is used to make response very directional The cadmium sulfide sensor gives spectr
12. consideration if indeed itis considered at all The software must be compatible with your computers and you must have an appropriate licence for the use of the software Good software should install without complication and should provide the ability to analyse and suitably present the collected data It is well worth the time and effort required to become familiar with the software and its functionality and use 21 8 1 Philip Harris Harris e log 8 1 1 Harris e log Il datalogger Width 186 mm attop 182 mm at bottom Height 130 mm Depth 41 mm Weight 649 g Memory 4 Mb Screen size 80 mm by 60 mm LCD This gives a reasonably clear picture Carry case Not made although Gratnell tray linings are available Ports Top vertical face power 2 USB ports Front vertical face 4 mini DIN ports for sensors Battery e Log Il has two lithium ion rechargeable batteries These may be charged either from the mains or when connected directly to a computer Initial charging takes about 8 hours and fully charged the battery will last for about 8 hours depending on the sensors used Wireless connection Upgrades No facility for Bluetooth connection Available through the Internet Manual Quickstart guides and user manuals are provided and are clear Field use Although not large the weight of the e log Il is greater than many other loggers Nevertheless carrying and use in the
13. discussion of the problems of using different types of oxygen electrodes is given in section 17 3 8 of the Laboratory Handbook this is important reading It is however worth briefly mentioning the important points here e Readings are affected by temperature as this rises less oxygen is dissolved in water but an electrode usually becomes more sensitive the two effects to some extent compensate for each other Always try to take readings at the same temperature if this is not possible corrections must be made Section 20 6 7 of the Laboratory Handbook gives a table showing how the concentration of dissolved oxygen varies with temperature e Readings may be affected by the presence of chloride ions so measurements of oxygen levels in rock pools need adjustment e Readings are affected by pressure changes it is therefore difficult to take measurements at a wide range of different depths of water e Electrodes must be stirred in the samples of water being tested since they use up oxygen and deplete levels in the water immediately adjacent to the probe If water is not stirred the readings decrease often dramatically Stirring the water may however create problems by causing oxygen to dissolve into the water from the air Stirring actions should therefore be slow constant and not unduly agitate the surface of the water In the lab a magnetic stirrer is helpful The need for stirring is a significant problem if an oxygen electrode is to b
14. electronic device into which a range of different sensors can be plugged in order to take observations of environmental parameters Many dataloggers are in effect small computers and some are now so sophisticated that they can not only record data but also store it and analyse it Others record and save data but need to be connected to a computer the data downloaded at a convenient time and then analysed Interfaces can not store data themselves and must be connected to a computer to record store and interpret observations Many loggers though not all have their own display Very recent technological developments offer even more options A different approach has been developed using software which modifies Microsoft Excel on a PC laptop or mini notebook enabling it to be used to pick up and display data collected directly via new USB sensors 3 Scope and organisation of the guide Scientific studies of the environment investigating pollution and work in ecology are an essential part of the school science curriculum The essential National Curriculum requirements for Key Stage 2 have been included in this guide to encourage secondary schools to build on what the pupils have learned in their primary science lessons This guide includes the following e an indication of the current requirements of the environmental aspects of the National Curriculum and of external examination boards e information on the range of environmental parameters on whi
15. experiments and access to a periodic table display As an alternative the data was saved to a separate computer using the Logger Lite or Logger Pro software and analysed there The Labquest software is Linux based but is compatible with Logger Lite It is possible to connect Labquest direct to a printer without linking to a separate computer Vernier also produces a series of books of experiment suggestions relevant to different aspects of science Each book comes with a CD version Whilst these are written for the American market many of the ideas could be adapted for local curriculum needs Costs Supplier Catalogue number Price Granet South of England IDS North of England Vernier Labquest Includes Logger Lite software and temperature probe LQ QSP 319 00 43 8 4 2 Vernier Sensors Environmental Comment Parameter Barometer The BAR BTA has a range 81 to 106 kPa 25 to 31 5 in mercury It is suitable for air pressure studies where air pressures are within the usual range It gave a clear accurate and suitably fast response Carbon dioxide This measures gaseous carbon dioxide levels within two ranges O to 10 000 ppm and O to 100 000 ppm The lower range is probably more useful and more sensitive The sensor package includes a 250 ml gas sampling bottle Monitoring carbon dioxide variation in an occupied room gave sensible results though response was slow
16. field is not too difficult Operation This datalogger can be used a stand alone device to record display and graph data or as an interface to another computer Installation of the USB driver from CD supplied before charging is easy and quick Navigation is by keypad The start screen gives clear choices set up and run view saved results change settings and shut down Change between screens is simple using an arrow button Usage is straightforward and the screen is easily restored from screen saver mode Default sampling is 60 readings at 1 second intervals Changing these settings to suit the investigation is straightforward Datalogger auto recognises a sensor pictorially on the sensor status bar Up to 4 sensors can be tracked at once Starting and stopping logging is clear and labelling of experiments uses letter buttons on the case front much as in texting An alphanumeric keypad is also available Screen auto adjusts y axis to appropriate units for several sensors Various modes are available to match investigations quickstart continuous for 0 5 sec normal burst fast log for 1 sec duration for very fast events snapshot irregular but labelled intervals and frugal modes Delayed starts are offered as an option Results can be tabulated or graphical Datastorage really a must for field or remote use an option Data may be saved direct to a memory stick or to a separate computer Costs Supplier Catal
17. have thermistor probes They are also widely used in temperature datalogging sensors The range of temperatures measured is between 50 C and 200 C Thermistor sensors can be quite small and may have low response times which can in liquids be better than with mercury in glass thermometers Thermocouple A thermocouple measures the difference in temperature between two junctions of dissimilar metals This gives rise to a voltage which is registered by the sensor and produces a display These tend to be more expensive than a liquid in glass thermometer The K type is the most common Because of their good thermal conductivity thermocouples usually have a low response time Thermocouple systems can cover temperature ranges from 250 C to beyond 2000 C Some instruments that might seem attractive for environmental monitoring have in fact been designed for the food and hygiene industries and the requirements and rigours of the school laboratory or the field were not a consideration in their design Some may even still be calibrated in Fahrenheit Response time might be an important factor for some users Response times are measured in air from 40 C to 22 C and in liquid from 100 C to 0 C There is little to choose between mercury and electronic thermometers in their equilibration times in air Immersion depth is not usually critical but immersion under 2 cm gives a slower response in liquid 6 9 Measuring
18. included in section 17 2 3 of the Laboratory Handbook 6 11 Measuring ultraviolet radiation Ultraviolet radiation has wavelengths in the region of 400 to 100 nm which are shorter than visible light but not as short as X rays There are three main types of UV radiation UV A UV B and UV C All are emitted by the sun but almost all UV C which is the most harmful to human beings is absorbed by the earth s atmosphere Over 98 of the UV radiation reaching the earth is UV A Table 6 Type of UV radiation Approximate wavelength range UVA 400 315 nm UVB 315 280 nm UVC 280 100 nm There are a number of benefits from UV radiation Vitamin D production is stimulated by exposure to UV B Fluorescent lamps produce UV radiation by ionising low pressure mercury gas A phosphorescent coating on the tube absorbs the UV radiation and emits visible light A number of birds reptiles and insects can see into the near ultraviolet range A number of fruits flowers and seeds stand out more strongly at ultraviolet wavelengths Indeed the plumage of some more exotic birds stands out more distinctively in this range too However UV radiation also is of environmental concern because it can give rise to skin sunburn or worse to skin cancers on over exposure to strong sunlight or other sources of UV The shorter the wavelength the more harmful the effects on human beings The longer wavelength UV A radiation is also emitted by sunb
19. model The UL and WL had no in built sensors but had four sensor ports The XD has four sensor ports and a small screen while the SE has temperature and light internal sensors and two sensor ports but no display screen Costs Supplier Catalogue number Price Sciencescope Logbook GL S1313 200 00 Logbook GL wireless 1314 250 00 Logbook ML USB 1315 150 00 Wireless adapter 1796 45 00 54 8 6 2 Sciencescope Sensors Probes come in neat cylindrical plastic containers Environmental Parameter Comment Air pressure barometer The S1679 can be used to measure air pressure from 830 to 1150 mbar with a resolution of 0 5 mbar and can be used at normal altitudes This model was not tested Carbon dioxide The S1853 was not tested but is designed to measure carbon dioxide levels in the range 0 to 100 000 ppm resolution 1 5 The detector cell life is about two years and replacement cells are available Conductivity The S1896 consists of a base unit and probe and has a range of O to 100 000 uS resolution 1 5 The probe comes dry though long term storage should be in deionised water in a protective bottle Calibration as with most conductivity sensors is quite a lengthy process using standard KCI solution Tests on water samples gave sensible conductivity values Electrosmog The S1850 was not tested but is used to detect broadband electromagnetic radiations and covers the
20. more accurate multiple point calibration both of which are lengthy processes Most soil moisture sensors use capacitance to measure dielectric permittivity of its surroundings The sensor produces a voltage proportional to the dielectric permittivity of soil which is a function of the water content Not all suppliers sell soil moisture sensors Measurement of the levels of minerals such as nitrogen phosphorus and potassium in soils is possible using indicator strips and chemical test kits produced for horticultural use Various methods are available for measuring the levels of natural or pollutant ions within the soil Most are performed on soil samples mixed with water and so only measure soluble components of the soil Clearly the readings only have significance if equal volumes of soil are used In some instances the use of tests designed for monitoring river or stream water samples may provide more reliable assessments of water soluble soil ion contents See section 17 2 3 in the Laboratory Handbook Some sensors are designed to test for specific ions These will be mentioned briefly in Section 8 but tend to be very expensive Additional information is in section 17 2 2 of the Laboratory Handbook 6 7 Measuring sound Sound levels are commonly measured in dBA which is a unit like the lux that is adjusted to allow for the human perception of sound dBA is a measure of sound intensity or loudness the A is a weighting added to a soun
21. the levels of the gas in different situations such as near major roads near side streets and in open countryside Such sensors will usually detect up between 0 and 10 PPM of nitrogen dioxide Not all companies produce such sensors and they are relatively expensive Sulfur compounds are present in most fossil fuels to a greater or lesser extent When these are combusted they give rise to sulfur dioxide which is toxic can lead to asthma attacks and also gives rise to acid rain It should also be noted that significant amounts of sulfur dioxide are released into the air from naturally occurring events such as volcanic eruptions Sensors will usually detect up between O and 10 PPM of sulfur dioxide Not all companies produce such sensors and they are relatively expensive 7 Factors to consider when choosing systems Assuming that a school has decided to revise its approach to environmental monitoring and possibly to purchase one or more dataloggers and accompanying sensors there are still a significant number of factors to take into account Most are self evident but a few may not have been taken into consideration Some of the major ones will probably include e cost e existing provision for environmental monitoring in the school e the approach to be taken to environmental monitoring e age range over which the datalogging equipment will be used e usage of equipment by other disciplines within the school thus possibly dividing the cost
22. used and takes a few hours to recharge Wireless connection The EX model is wifi enabled The SX and BX are not Manual It comes with Quick start and Multilab guides giving clear instructions on using the Nova 5000 as a stand alone device or linked to a computer Upgrades Upgrades are available from the web site Weather proofing The Nova 5000 is not waterproof In the field users are advised to store in a waterproof carry case Field use The Nova is portable but is larger and quite a lot heavier than most loggers tested and cannot be held in one hand easily for use in the field Operation This neat datalogger can be used a stand alone device to record analyse and display data or as an interface to another computer As with a number of similar instruments this is in effect a small computer in its own right 58 Operation continued Installation of the USB driver from CD supplied before charging is easy and quick There is a built in temperature sensor giving ambient temperature readings and a built in microphone and sound sensor Access is by a start button and navigation is by a keypad below the screen which proved easy to follow Power saving operates restart is from any button Sensors are easily connected via leads and are instantly recognised by the logger Several sensors can be tracked at the same time The remaining keys access the menu edit and zoom facilities Th
23. water flow rate The cheapest method involves the use of Pooh sticks and a stopwatch but this lacks scientific credibility and cannot show differences in flow rate at different depths or even at different points across a stream Instruments available are already calibrated and use the force of water flow to rotate an impeller or occasionally to move vanes apart They can be lowered into the water to the required depth but require ready access to the water from the bank of a stream or river or wading out into the water to position the instrument Their use therefore has implications for health and safety and for management of fieldwork by students Suppliers go to great pains to underline this fact especially in view of the deaths of a number of people in sudden unpredicted water surges 6 10 Measuring water pollutants Indications of the level of pollution in water may be obtained by using meters to measure conductivity and or dissolved oxygen see sections 6 1 and 6 4 above for details Chemical tests using indicator strips comparators or reagent kits are available to measure a wide range of pollutants Some sensors are designed to identify specific ions such as the ammonium nitrate sulfate ions or as mentioned in 6 6 above a number of metal ions These tend to be very expensive and would only be relevant to specific types of environmental investigations For cost reasons they have not been reviewed in this guide Further information is
24. 105 sensor has a built in dipole aerial to detect field strength of RF signals measured in watts metre in the 800 to 2 500 MHz range Testing in the lab gave a comparative measure of RF signals arising from different equipment such as mobile phones alarms etc and showed that certain types of shielding are possible 37 Environmental Parameter Comment Light Four models are available but not all are likely to be used in environmental monitoring The SPX LUX DA61276 covers 0 to 100 000 lux The silicon photodiode is sensitive to both visible and IR making it suitable for outdoor use e g in sunlight and for measuring light in darker areas such as forest floors The spectral range is 400 to 1 100 nm A cheaper general purpose model DA61271 also covers visible light and IR and measures light levels on a 0 to 100 scale and would be suitable for measuring precipitation rate for example There is also a slightly more expensive Smarteye model DA61204 which includes a set of coloured filters that can be used to block IR pH Several untested versions are made Model DA61262 and can be used to link a standard pH electrode to a loglT device The DA61206 is a pH sensor and electrode while the DA61278 has an adjustable sensor As with almost all pH electrodes the glass bulb must be stored wet Relative humidity The humipro DA61267 measures water vapour content relative to saturated air and responded very qui
25. 15 000 lux though it does so in three bands 0 to 600 lux O to 6 000 lux and 0 to 15 000 lux making it a suitable all purpose sensor On testing there was a distinct time lag between changes in light intensity and the recorded response but test results were within the expected range Notes Sensor packages did not carry information notes On occasions these would have proved helpful Oxygen The XLS1047 was not tested but is designed to measure gaseous oxygen concentration in the range 0 to 100 It should be suitable for a range of environmental investigations including photosynthesis and respiration pH The XLS1005 operates over the usual pH range of O to 14 The design is typical of glass pH electrodes and the bulb has to be stored in what is presumably a buffer solution Response was as expected and pH values recorded were within the anticipated ranges Relative humidity The XLS1008 covers the full range 0 to 100 with a resolution of 0 1 Under test results were within the expected range but response rate was on the slow side Sound This sensor has a good range from 40 to 110 dBA It provided a rapid response rate and sensible values to investigations of domestic noises and to simple environmental situations Temperature The stainless steel thermistor sensor operates over the range 25 C to 125 C 0 1 C and showed a suitably fast response time under test I
26. Also since the conductivity measurement of a solution is influenced by the cross sectional area of the sample all comparative readings must be carried out with the sample in a standard beaker or other container Where there is a choice of conductivity electrode available it is wise to choose a plastic body version for use in the field Ease of taking readings If a school opts to purchase a conductivity meter then it should be noted that these usually give a simple direct reading Others however require that the meter reading is multiplied by the setting of the range switch and often also the cell constant of the electrode in use This may be 1 0 or very nearly 1 0 and so poses few problems of obtaining meaningful readings immediately The cell constant of an electrode may however be more than 1 0 or with a special electrode used to extend the range of the meter have a value of 10 Some students may be confused by this additional complication Conductivity is strongly temperature dependent so some equipment may have automatic temperature compensation as a built in facility If not care must be taken to allow for variations in temperature when comparing readings For each degree C increase there is an approximate 2 rise in conductivity Conductivity electrode maintenance Sheathed electrodes should be replaced in the sheath Unsheathed electrodes must be kept clean and preferably stored in deionised or distilled water this may create som
27. As before there is a default setting for straightforward logging but the recording duration frequency of readings and number of points displayed were easily altered to suit the investigation Data was tabulated analysed and displayed Analysis tools include tangent drawing gradient calculation smoothing and integration to obtain areas under graph lines etc Overall this proved very straightforward to use 57 8 7 Fourier Nova 5000 8 7 1 Fourier Nova 5000 EX NOVA Width 237 mm at widest Height 186 mm Depth 44 mm including feet Weight 1091 g 1225 g with battery Memory 64 Mb RAM and 128 MB NAND flash memory Screen size 155 mm by 93 mm The very large screen gives a very effective direct display Carry case A carry case is available with holes for the screen and sensor links The base has two folding stand supports for desktop use Ports Top vertical face 4 sensor ports audio in out and power jack socket and flashcard slot Left hand vertical face USBs for connecting to another computer and printer or external keyboard Right hand vertical face USBs for connecting to printer or external keyboard and network connection port Battery Rechargeable NiMH battery pack with lithium backup battery Charging is either from mains or when connected to computer The battery should last at least a day in field use though this depends on which sensors are being
28. Colorimeter This four wavelength colorimeter was not tested but would be useful e g in determining concentrations of unknown solutions It includes a supply of cuvettes Wavelengths covered are 430 nm 470 nm 565 nm and 635 nm It has automatic one button calibration Conductivity The conductivity probe can be used for testing total dissolved solids or such things as salinity in water samples Although not tested it has three different sensitivity settings and automatic temperature compensation over 5 C to 35 C Dissolved Oxygen This sensor has a range of O to 14 mg l dissolved oxygen but was not tested It has built in temperature compensation over the range 0 C to 35 C It requires the usual care with storage and maintenance Light A single silicon diode unit covers three ranges that can be selected via a switch O to 600 lux 0 to 6 000 lux and 0 to 150 000 lux The spectral range is similar to that of the human eye The lowest range proved to be the most sensitive but the range chosen will depend on the investigation pH The sensor is the usual Ag AgCI combination electrode with storage bottle and solution Unless very high accuracy is required it is not necessary to recalibrate As with all pH electrodes maintenance and proper storage are essential and even then the electrodes have a limited life Relative humidity The range is 0 to 95 accuracy 5 Unless very high accuracy required calibration proved unn
29. Granet SMS BTA 84 00 Sound IDS Granet SLM BTA 153 00 Stream flow rate sensor IDS Granet FLO BTA 120 00 Temperature IDS Granet TMP BTA 27 00 TPL BTA 65 00 Ultra violet IDS Granet UVA BTA 96 00 UVB BTA 97 00 There are a number of other sensors for the logger but they are not relevant to a study of environmental factors but the full range should be taken into account when deciding about which logger and which sensors to buy 45 8 4 3 Vernier Logger Pro and Logger Lite software Compatibility The software is compatible with Windows XP and subsequent packages including VISTA Licence Logger Pro comes with a full site licence Installation and operation The CD was readily accepted by the computer and Labquest was readily recognised The opening screen offers a range of icons parallel to those on the Labquest As before the sensors were instantly recognised on screen The menu offered the same range of continuous logging individual readings e g at specific events or snapshot logging The start icon operated logging which was tracked by a meter or by a graphical display on screen The graph autoscaled to accommodate the data collected Several runs were collected and displayed together Snapshot mode allowed sensor readings to be captured on demand and the data was readily stored As before there is a default setting for straightforward logging but the recording period and frequency of
30. R142 Equipment and Materials for Environmental Monitoring March 2009 March 2009 R142 Equipment and materials for environmental monitoring Contents R142 Equipment and Materials for Environmental Monitoring Ts General INLFOCUCHON strass raras vastranecaseeesenanerebeve sees secesenederesceunenenensbecesceebebeaeeanennnct ahs 1 2 What is environmental datalogginGs2 cs2c lt secescuesecescresecencreseecnereserenereseecberescuebereseuebeneseeene 1 3 Scope and organisation of the guide s ccscicscicscicocccscicsccoscicsccosciosccesciesecoseceso 1 4 National curriculum and examination board requirements ccccccceeeeeeeeeeeeeeeeeeees 3 5 Choosing the right type of equipment c s ccsciosoioscicssicscicscccscicsciosciosccoscicscccscceso 5 5 1 Purpose built meters for measuring single or multiple environmental factors 6 5 2 Analogue or digital meters ra eararerenaaananaaraner eae aaaaanananeereaanada 6 5 3 Meters or chemical test kits aerea aa acaranea eae aaanananaaeereanana 6 5 4 Sensormeters or sensors linked to dataloggers siena 7 5 5 USB sensors linked to a computer erre eacaaaararer era anaaanananeeea 7 5 6 Reliability and ease Of use iria aa acararereena nana anaaaaeerenenanaaanananeaaa 7 6 Measuring environmental parameters ioosoo osso osso ooioooosoonocoocoonocooccano
31. ake temperature readings in inaccessible locations for example at different depths of water although a maximum minimum mercury thermometer could be used for such readings Electronic sensor thermometers would appear to be suitable alternative instruments Instruments with probes can easily be pushed into the soil beneath bark etc The main types of sensors employed in electronic thermometers include thermistors and thermocouples Resistance thermometer sensors are likely to prove too expensive for most school uses For a full discussion of the pros and cons of sensor type and other information on electronic thermometers refer to section 10 7 3 of the Laboratory Handbook Table 5 Electronic thermometer sensor types e g platinum temperature coefficient The change in resistance produces a display via the sensor Sensor How it works Suitability for environmental studies Metal As the temperature rises the resistance These are accurate but very expensive resistance of the material also rises a positive Resistance thermometers provide greater precision operating within the range 200 C to 850 C Semi conductor thermistors As the temperature increases the resistance of the semiconductor material decreases i e a negative temperature coefficient The change in resistance is registered by the sensor and can be transmitted to give a display These are inexpensive to produce and most models used in schools
32. al response close to that of human eye Response is suitably rapid for general use but not for sensing rapid changes in light level Philip Harris does not produce a turbidity probe but this light sensor could be used instead where water studies are involved pH Comes as body and separate detachable probe In contrast to most pH probes this may be stored dry and can be used without further calibration for basic testing For greater accuracy wet storage is essential and further calibration using a standard buffer solution is needed Relative humidity The sensor measures relative humidity on a 0 to 100 scale It gave a reasonably short response time and sensible values on testing Sound Operates over range of 50 to 110 dB The sensor offers a choice of fast or slow response according to investigational needs via a switch on sensor body Testing yielded appropriate values Temperature 10 C to 110 C This sensor is suitable for use in air or non corrosive liquids The sensor element is housed in the tip of a thin stainless steel sheath and gave rapid response to change of location Also has LED giving colour change from below 60 C to above 60 C There are a number of other sensors for the logger but they are not relevant to a study of environmental factors but the full range should be taken into account when deciding about which logger and sensors to buy It is likely that the range of environmental sensors for the
33. and technological developments Science at Key Stage 4 How science works Data evidence theories and explanations 1 Pupils should be taught a how scientific data can be collected and analysed b how interpretation of data using creative thought provides evidence to test ideas and develop theories Practical and enquiry skills 2 Pupils should be taught to b collect data from primary or secondary sources including ICT sources and tools d evaluate methods of collection of data amp consider their validity amp reliability as evidence Communication skills 3 Pupils should be taught to a recall analyse interpret apply and question scientific information or ideas C present information develop an argument and draw a conclusion using scientific technical and mathematical language conventions and symbols and ICT tools Breadth of study 5 Organisms and health In their study of science the following should be covered a organisms are adapted to their environment 8 Environment Earth and universe a the effect of human activity on the environment can be assessed using living and non living indicators GCSE Science subjects Environmental studies are an integral part of GCSE courses The four major examination boards in England and Wales are required to produce their GCSE examination courses in line with the QCA specifications New courses in the sciences were introduced for first teaching in 2006 most other sub
34. ange of 0 to includes sensor and probe 20 mg l accuracy 0 2 mg l allows quite small changes in dissolved oxygen content to be measured The membrane comes in a cartridge and a spare membrane is provided Oxygen gas PS2126 measures oxygen gas concentration in ppm over a wide range 0 to 100 1 enabling it to be used for a variety of purposes from oxygen content in air samples to air quality to respiration experiments and breakdown of hydrogen peroxide Calibration should be not necessary though for very accurate work instructions are given as to how this could be done The pack comes with a sampling bottle and a sensing element 49 Environmental Parameter Comment pH PS2102 includes both sensor box and pH probe having the typical range of O to 14 resolution 0 01 pH The usual issues arising from storage care and maintenance of the probe apply and calibration against known pH buffer solutions is essential unless tests are purely qualitative pH may also be measured using PS2147 the pH temperature ISE ORE sensor Sound PS2109 is also flexible having three overlapping sound level ranges 30 to 70 dB 50 to 90 dB and 70 to 110 dB with an accuracy of about 2 dB Although not tested it has the flexibility to measure both sound level measured in dB and sound intensity measured in micro Watts per sq m The screen display shows both dBA matching human ear sensitivity and dBC equal re
35. ant but essential for the survival of the planet and all its life forms 2 Whatis environmental datalogging Environmental datalogging is the recording of relevant information over a period of time It can be carried out manually observing experiments first hand making practical observations and writing them down or it can be done electronically using a datalogger or by other electronic means This may have a variety of advantages Being at the site where investigations are taking place may not always be possible for a variety of reasons not least because the observations may be taking place over a long period of time Equally the experiment may require very short intervals between readings and it may not be physically possible to make the observations and record them in the very short time span needed Electronic dataloggers enable both these extreme situations to be met as well as the more routine investigations that require readings to be taken at more manageable intervals Additionally many investigations are most readily interpreted by plotting a graph of the results It is usually possible for the software that accompanies dataloggers to plot and draw the graph for you thus freeing time for discussion and interpretation There will be times however when it is precisely those graph drawing skills that are a major part of the aims of the activity in which case it would simply be the tabulated results that would be used A datalogger is simply an
36. argeable NiMH battery and can be charged from the mains or from computer when connected ML battery operation should give up to 200 recordings The GL should last at least a day with Bluetooth on in field use though this depends on which sensors are being used Wireless connection ML does not have wireless facility but GL does as an optional extra Manual It comes with a teacher s guide giving clear and relatively concise instructions on using the Logbook ML or GL as a stand alone device or linked to a computer and the software Upgrades Software can be updated from the Sciencescope website Weather proofing The Logbook ML is shower proof but not waterproof In the field users are advised to store in a waterproof carry case Field use The modest weight and size make this logger easy to use in the field Operation This neat datalogger can be used a stand alone device to record and display data or as an interface to another computer There is a built in temperature sensor 0 C to 45 C which can be overridden by the plug in thermometer a light sensor 0 to 110 000 lux and a sound sensor 50 to 110dB Access is by an on off button and navigation is through two further user buttons also below the screen that proved easy to follow The GL has extra buttons Power saving operates after two minutes though the interval is longer in meter screen or snapshot mode Restart is from any button 53
37. at are used to show the pH can affect the results and contamination of electrodes can introduce large errors Carbon dioxide from the air or alkali from glass vessels may all too easily alter the pH of natural water samples The following points are essential for reliable and accurate work in the field with a pH sensor electrode with adapter e The probe must always be stored and transported in distilled water or pH 7 buffer solution e To avoid contamination scrupulous care must be taken to clean the electrode in distilled water before any measurement e Calibration of the meter with a known buffer solution is best done as near as possible to the time of measurement and ideally a buffer or buffers close in pH to the value s to be measured should be used for this calibration e Also important is the need to protect the socket on the meter into which the electrode is plugged from contamination with water soil and other debris when a datalogger or meter is used outside All of these requirements for improved accuracy make pH measurement in the field more difficult and require the careful transport of additional items to the site pH values are affected by changes in temperature and unless equipment with automatic temperature compensation is used corrections will be needed particularly if all readings are not made at the same temperature Section 20 6 8 of the Handbook gives a table showing how pH varies with temperature Selecting the corre
38. ata sample collection could be altered to suit for continuous logging The frequency of manual sampling is still determined by the operator with the same range of options Data display as before could be graphical tabulated or meter Up to two graph lines could be displayed at a time with a y axis at each side of the graph Saving of data is straightforward Analysis tools are the same including graph smoothing autoscaling zoom selection of graph sections gradients differences area linear fit etc It also proved straightforward to modify the table of data and to add notes on activities via the keyboard The extensive calculator functions are still accessible as before Overall this software proved straightforward to use once installed 52 8 6 Sciencescope 8 6 1 Sciencescope Logbook ML Width 124 mm at widest Height 115 mm Depth 40 mm including feet Weight 257g Memory Logbook ML has 8 files with up to 48 days recording on each Screen size 58 mm by 13 mm on ML The GL has a larger screen with graphical display which is more easily seen Carry case A carry case is available Ports Top vertical face power jack point and USB to connect to a computer Bottom vertical face 2 sensor ports GL has 4 min jack socket is for the ML temperature probe and in built temperature light and sound sensors Battery 9 V PP3 battery or can be operated from the mains GL has a rech
39. ave a separate external probe but many have the humidity detector built into the meter housing this could limit the ability to take readings in awkward places This is not so much a problem for humidity sensors The sensors of some humidity meters are very delicate and must not become wet not a particularly desirable feature for fieldwork near streams and ponds with wayward pupils Sensors may be destroyed by vapours from organic chemicals so safe storage of the equipment away from such chemicals is important Some humidity sensors work best only in a moving current of air so measurements in confined or enclosed places may pose difficulties Response times are sometimes very slow necessitating leaving the sensor in place for an extended period For further information on humidity refer to sections 17 2 1 and 17 3 2 of the Laboratory Handbook Before investing in a meter or sensor to measure relative humidity it is worth considering whether an approximate indication of humidity levels using an inexpensive paper hygrometer might give sufficient accuracy Another possibility is the use of cobalt thiocyanate papers which give a more distinct colour change than cobalt chloride papers going from blue to pink with increasing humidity 9 6 3 Measuring light Measurements of light in the field would seem to be a simple matter point the light sensing device in one location and take a reading repeat this at another location and compare results Differenc
40. ch measurements can be taken e a general discussion of points to be considered in choosing the most appropriate equipment for the requirements of a school or college e information on taking measurements of various environmental parameters e an evaluation of a range of sensors and dataloggers 1 This guide will consider equipment that can be used to explore a number of environmental parameters as listed below e Carbon dioxide and other aerial gases e Conductivity total dissolved solids and salinity e Humidity e Light e Oxygen aerial and dissolved e pH e Soilions e Sound e Temperature e Ultra violet radiation e Water flow rate e Water quality R142 will not discuss in detail equipment for measuring air pressure wind speed rain fall etc involved in studies of meteorology Reference should also be made to sections 17 2 and 17 3 of the Laboratory Handbook which discuss the measurement of environmental parameters by electronic and non electronic methods The Handbook material describes various tests not included in this guide and also gives background information on some of the theory behind the operation of the apparatus discussed in R142 Most measurements will be made using a datalogger or a specialised meter such as a pH meter but in some cases a chemical test may be involved and readings are then typically made by matching coloured reactants against a standard colour scale or recording the number of tab
41. ched Schools may decide that there are educational advantages to using meters with inbuilt sensors or linked to suitable sensors to measure environmental changes over moderate periods of time noting readings down and analysing them at leisure This certainly takes students through the stages of the process more systematically but it also presents greater demands on perseverance and the time needed to complete measurements and analyse them especially when problems are encountered It is also much more difficult to use a simple meter and sensor to follow very rapid changes or ones which take place over a longer period of time such as a full day or more By contrast most dataloggers linked to appropriate sensors now have the facility to take readings at very short or very long intervals Most also incorporate a mini computer which will collate and save the data recorded in tabular or graphical form and carry out detailed analyses on the spot Clearly to ensure the effective and efficient use of dataloggers especially in the field teachers and students need to become familiar with the operation of the datalogger plus associated computer and software in advance 5 5 USB sensors linked to a computer At the end of 2008 software was developed which would enable direct plug in USB sensors to send data directly into any version of Excel spreadsheets and be tabulated graphed and analysed This approach when further developed would limi
42. ckly It covers the range 1 to 100 and gave results within the expected range No water or condensation should be allowed to reach the sensor head There is also a cheaper general purpose humidity sensor DA61265 which was not tested but which is slower to respond though may be suitable for checking humidity of different locations rooms or transpiration of plants etc Sound DA61205 has a range of 50 to 110 dBA 5 Testing indicated a satisfactory response rate and matched other similar models As with many sensors it is not designed to be water resistant but also needs to be sheltered from direct wind gusts It can also show sound waveform Stream flow The DA61281 has an impeller equipped with a two piece 1 meter rod and can be held vertically to measure water flow in streams between 5 and 100 cm deep Though not tested in the field lab tests showed it to be sufficiently sensitive for comparative measurements though the connecting wire at the front of the impeller was awkward to manipulate Safety precautions are well emphasised Temperature Three temperature sensors are produced and a K type thermocouple which is unlikely to be used in environmental monitoring Hitemp 10 C to 110 C DA61272 is a general purpose thermometer suitable for air and liquid measurements It has a small stainless steel tip and on testing responded quickly to rapid temperature change The waterproof nature long cable and light weig
43. cluding an oscilloscope frequency counter and logic analyser but for environmental monitoring alone the BX would be adequate Costs Supplier Catalogue number Price Griffin Education Datavision BX guide and case CRD 810 010T 299 00 The single user software is extra Griffin Education Datavision CX guide and case CRD 800 010D 359 00 The single user software is extra Rapid Datavision BX guide and case 85 2679 286 00 The single user software is extra Rapid Datavision CX guide and case 85 2677 344 00 The single user software is extra TAG learning Datavision Datavision serial or USB 429 00 Timstar Datavision BX guide and case DA61225 299 00 The single user software is extra Timstar Datavision CX guide and case DA61223 359 00 The single user software is extra 32 8 3 2 DCP loglT Voyager SX LogiT Width 78 mm at top serem Height 165 mm eee Depth 41 at deepest 35 mm at shallowest Weight 238 g Memory Will store 4 experiments with 250 readings per sensor in Voyager autolog mode but this can be increased using a free firmware update Screen size 52 mm by 16 mm small screen limits the amount of data displayed Carry case Comes with a hard carry case Ports Top vertical face 3 large DIN ports for sensors Bottom vertical face serial socket Battery Four AA alkaline batteries These a
44. ct pH electrode Glass electrodes are very delicate and for fieldwork it is sensible to choose a plastic bodied version which will be a little sturdier If the pH of soil is to be measured then a special spear electrode must be used and this pushed gently into the soil There are certain models of separate pH sensors and meters specifically designed for horticultural use which employ a metal probe for soil pH measurements A pH electrode for taking readings in water also uses this type of electrode These instruments lack the accuracy of meters using glass electrodes Some suppliers provide a general purpose electrode and one suitable for low conductivity solutions If measurements of the pH of acid rain are contemplated a special electrode is required for accurate work but these are quite expensive Calibration of pH electrodes probes Suppliers usually provide detailed instructions about calibration but this usually involves use of two or three standardised buffer solutions to adjust the sensor readings The choice of these buffers may vary with the temperature of planned usage Storage and maintenance of oxygen sensors probes The level of pH electrode storage must be maintained and the pH sensitive membrane must be kept wet The glass bulb may be cleaned with 0 1 M HCl for 10 minutes or so and then rinsed thoroughly in distilled water before immersing in the storage solution again Using indicators to measure pH Because of the difficul
45. curacy Colorimeter The DA61294 includes a cuvette but avoids the need for separate colour filters by use of multicolour LED emitters It measures absorbance of light through a coloured solution as and hence transmittance Calibration is via selection of wavelength and calibration to 100 transmittance It proved to be very sensitive in use though drift was noticeable unless stabilisation time was allowed It is suitable for e g comparing turbidity in water samples formation of algae etc Conductivity The DA61270 comes as an adapter and probe set operating up to 20 000 US It comes with a long cable simplifying use in water quality investigations It can be calibrated with a standard solution close to that being tested The need to allow stabilisation time makes this a slow process The probe should be washed in distilled water after use and stored wet Dissolved Oxygen The DA61207 probe comes in a set with an amplifier membranes and KCI solution It has auto temperature compensation over 5 C to 45 C range The electrode needs care as with the pH electrode In use the solution must be stirred to avoid oxygen depletion near the probe Notes also suggest sterilisation for 10 to 20 minutes It is quite slow and complex to use as with other oxygen probes Electrosmog Electrosmog is name given to man made RF emissions that may interfere with hospital or aircraft instruments and some believe health DA71
46. d Since the majority of sensors made are not interchangeable between systems this could be an important issue Use of datalogging equipment across the science department Datalogging is not only a valuable tool in environmental studies It has a variety of potentially valuable uses in other science disciplines such as chemistry studying rates of reaction and physics studying velocity and acceleration for example Although a wider range of sensors would need to be purchased these additional uses could make the outlay of a large amount of money more justifiable The balance between use in the laboratory and in the field Some environmental investigations can be carried out in the laboratory but many are clearly more appropriately done in the field Portability of equipment usually the sensor s and datalogger becomes a much more significant issue Although the majority of dataloggers tested have a good battery life this may be an issue to consider if overnight recharging is a problem or if investigations lasting several days are planned The on screen display requirements in the field Choice will also be dependent on what range of display is required when in field use For example if all that is required is to be able to take readings and record for subsequent analysis the choice will be different to that required if analysis is required on the spot The range of on screen display varies significantly between models The balance between
47. d on the absorption of infrared light by carbon dioxide This was not tested Colorimeter DT185A was not tested but is supplied with three colour filters blue green and red as is the cuvette The absorbance range is 0 05 to 0 7 and transmittance from 20 to 90 i e not quite the same range as many colorimeters Conductivity DTO35A is comprised of a conductivity electrode an adapter equipped with an offset calibration screw and connecting link It covers the range 0 to 20 mS with an accuracy of about 1 which is good enough for salinity and water pollution testing It was not tested Light There are several light sensors The DTO09 1 has a single range of O to 300 lux and gave a Suitably rapid response Perhaps slightly more useful in environmental monitoring at little greater expense is the triple range DT009 4 which covers 0 to 600 lux O to 6 000 lux and O to 150 000 lux A small switch on the body of the sensor enabled rapid movement between the ranges It proved useful in both indoor and outdoor measurements and gave a rapid response The DT010 which may still appear in some catalogues has been discontinued Oxygen The DT222A comprises an oxygen sensitive electrode and a small processing box which has a calibration knob The sensor is designed to measure the oxygen in air up to 25 and and concentration of dissolved oxygen in aqueous solutions The range is selected via the Multilab software S
48. d pressure value to bring the measure nearer to that of the human ear This is not normally a problem since studies of sounds in the environment will invariably be in relation to their effect on humans However work involving investigations on say the sound related behaviour of bats should not use the dBA unit See section 17 3 11 of the Laboratory Handbook for further details Table 4 below gives some typical sound levels for comparison Table 4 Approximate loudness of sounds Sound levels dBA Pain level 120 Circular saw at 1 m 110 Loud motor horn at 30 m 100 Office duplicator at 1 m 80 Ordinary conversation at 1m 70 Ticking of a watch at 1 m 30 Threshold of hearing 0 This is the level that is dangerous even for short periods note that lower sound levels may be dangerous if endured for a period Many common environmental investigations relate to traffic or aircraft noise so dBA measurements are quite suitable 1 A number of instruments capable of detecting the ultrasonic sounds produced by bats are available schools might consider the use of a Batbox Baton at 60 VAT p amp p or the more sophisticated Batbox III D at 130 00 VAT p amp p both from Stag Electronics 13 6 8 Measuring temperature The mercury in glass thermometer although suitable for many applications in the laboratory is less than ideal for fieldwork It is easily broken and it is often difficult to t
49. de to the unit mho ohm To add to the confusion some instruments express the conductivity of solutions as total dissolved solids TDS with units of parts per million PPM mg litre or parts per thousand PPT as a rough guide PPM uS x 0 71 Finally salinity may be measured in g litre of NaCl Calibration and use in the field Conductivity measurements are affected by temperature and although many sensors and meters have automatic temperature compensation calibration should for complete accuracy be carried out with solutions at 25 C This could cause difficulties in the field Calibration of the electrode is therefore best carried out in the laboratory just before the instrument is used This involves using potassium chloride solutions of known concentration and sensors and electrodes normally carry a clear set of instructions Solutions can be purchased or are sometimes supplied with the meter but can also be made up in school Table 1 gives some suggested figures for the preparation of KCI solutions of different conductivities Table 1 Conductivity calibration solutions solder er KCI g litre 1400 0 744 3000 1 678 5000 2 833 1009 4 026 10000 5 741 Meters with integral electrodes will often be permanently damaged if completely submerged or dropped into water Tests are therefore best carried out on samples of water in appropriate containers rather than taking readings in situ
50. dence Pupils should be taught ta to try to explain how living and non living things work and to establish links between causes and effects 1b to test ideas using evidence from observation and measurement Investigative skills Pupils should be taught to 2f make systematic observations and measurements including the use of ICT for datalogging 2g check observations and measurements by repeating them where appropriate 2h use a wide range of methods including diagrams drawings tables bar charts line graphs and ICT to communicate data in an appropriate and systematic manner Breadth of study 1 During the key stage pupils should be taught the knowledge skills and understanding through a a range of domestic and environmental contexts that are familiar amp of interest to them C using a range of sources of information and data including ICT based sources d using first hand and secondary data to carry out a range of scientific investigations including complete investigations 2 During the key stage pupils should be taught to a use appropriate scientific language and terms including SI units of measurement to communicate ideas and explain the behaviour of living things materials phenomena and processes b recognise that there are hazards in living things materials and physical processes and assess risks and take action to reduce risks to themselves and others Science at Key Stage 3 1 Key concepts 1 1 Scienti
51. e other trigger available Direct collection of experimental results gives choice of auto scale or auto scroll As with the logger there is a results option of meter digital or analogue tabulated or graphical presentation of results Graphs can be in line bar pie etc format The cursor operated toolbar offers the option of finding graph gradient area difference and point values etc The styles menu offers enhancement of presentation to include headers table graph description labels etc 25 8 2 Data harvest Easy Sense Q 8 2 1 Data harvest Easy Sense Q Advanced datalogger Width 180 mm Height 110 mm Depth 43 mm Weight 393 g Memory 256 Kb Screen size 74 mm by 24 mm quite small for easy direct readout Carry case Comes with storage bag Spare bags can be bought Ports Top vertical face power socket 1 USB port e g for link to external computer Front vertical face 6 mini DIN ports for sensors two labelled A and B for timing operations Battery Rechargeable lithium ion battery Charging is either from the mains or when connected to computer Charging takes about 5 hours The battery should last up to 35 days in Easy Log or remote mode this depends on which sensors are being used This should easily exceed most school needs Users are advised to recharge every 6 8 weeks if not in use Wireless Some models are Bluetooth enabled allowing t
52. e left in a pond over an extended period to take readings with a datalogger Electrodes may be affected by turbulence in fast flowing streams and shielding may be needed Here however the local depletion of oxygen from the surrounding water will not be a problem Ensure air bubbles are not trapped against the electrode membrane e The performance of a galvanic probe is sluggish so several minutes of stirring are needed before readings are taken Electrode replacement There are several electrodes that are used with the variety of dissolved oxygen sensors available at prices schools can typically afford These are usually either a galvanic or a polyographic design made by companies such as Uniprobe or Russell The membrane used is most commonly Teflon and is now much more easily replaced Typically spare membranes are provided by the dissolved oxygen probe supplier these are filled with the electrolyte and screwed back in place Calibration of oxygen sensors probes There are different varieties of dissolved oxygen probes Some are based on a Clarke cell principle using a KCl electrolyte in a semi permeable membrane Temperature variation occurs in at least two ways oxygen diffusion across the membrane and the solubility of oxygen in the solution These may in part be compensated for by the instrument Instructions for calibration are usually given with the oxygen sensor and a full discussion in section 17 8 3 of the Handbook It should be no
53. e log Il dataloggers will be enhanced so that the range is nearer to that of the SensorMeters 24 Costs Sensor Supplier Catalogue number Cost Air pressure Philip Harris B8L 11368 69 95 Light Philip Harris B8L 11289 24 75 pH probe Philip Harris B8L 12245 21 25 body B8L 16342 56 50 Relative humidity Philip Harris B8L 11423 46 25 Sound Philip Harris B8L 11307 34 50 Temperature Philip Harris B8L 11290 25 95 8 1 5 Harris e log vision software Compatibility All post 98 systems Windows 2000 XP but may have problems with VISTA at present Licence Single multi and RM network licences available Installation and operation Easy and quick to install Opening screen offers a menu of new experiment template a library of existing experiment templates a saved work link live WEB or LAN connection data download from datalogger facility etc The new experiment template enables teachers to create their own template rather than use a prescribed one The template offers range of apparatus instructions result format etc all of which can be altered As with the logger data duration and frequency of sampling can be set for each specific investigation There is choice of experiment modes as with direct datalogger use normal economy burst snapshot or quick start Quick start has a default facility e g for delayed start relation to a specific event e g nightfall or som
54. e problems for transport out into the field After each use the electrode tip should be thoroughly rinsed in deionised water Solids should be removed with a small brush such as a toothbrush If readings become low and erratic the cell may need replatinisation refer to the Laboratory Handbook section 17 3 2 For some instruments the cell is an integral unit and maintenance may be difficult What to buy As is shown in Table 2 conductivity readings for water samples from a pure stream or a seashore rock pool are so different that separate electrodes may be needed if a wide range of conductivity measurements is anticipated Table 2 Conductivity readings for various water samples Sample Approximate conductivity Deionised water 0 2 1 uS cm Pure stream water 5 uS cm Tap water 50 500 uS cmt River water 1 mS cm Sea water gt 50 mS cm With meters that will measure only up to 10 2 S cm and also have a separate electrode it may however be possible to extend the range of the instrument by using a probe with a high cell constant 10 0 and so monitor salt water as well as fresh water For further technical background info on conductivity see section 17 3 2 of the Laboratory Handbook 6 2 Measuring humidity Humidity sensors may have advantages over single purpose meters for measuring relative humidity often described as hygrometers or thermo hygrometers when they also measure temperature Some of the latter h
55. e the use of datalogging equipment across the science department e the balance between use in the laboratory and use in the field e the on screen display requirements in the field e the balance between pupil practical work and demonstration e the location of work in the laboratory The reader will no doubt be able to add other factors to be considered before taking crucial and potentially expensive decisions Itis worth highlighting a few issues relating to each of these points Cost The majority of school and college science departments work to a very tight budget Few can afford to purchase equipment that will sit unused for months on end or is so difficult to use that staff are wary of its use at all Many companies offer trial use of loggers and often sensors before purchase thus enabling schools to evaluate ease of use and boosting of confidence before commitment Existing provision in the school Most schools will already have some provision for environmental monitoring either within the science department or in other departments such as geography It makes economic sense to consider what existing provision is suitable for continued use and might be compatible with any potential new purchases The approach to be taken to environmental monitoring There are frequently new developments in electronic data capture One of the newer ones is to avoid use of a datalogger altogether and to employ specially designed software to modify Exc
56. e touch screen is operated by a stylus and gave a rapid response The menu offers continuous logging individual readings e g at specific events or snapshot logging The start button operates logging which can be tracked by a meter or a graphical display on the good sized screen The graph autoscaled on both axes where necessary to accommodate the data collected Several runs may be collected and displayed together if required Snapshot mode allows sensor readings to be captured on demand and now the data is readily stored in the memory There is a default setting for straightforward logging operating for 50 seconds but the recording period and frequency of readings were easily altered to suit the investigation e g for very fast or much slower sets of changes Data may be tabulated analysed and displayed Analysis tools including graphing gradients differences area etc It proved straightforward to modify the table of data and to add notes on activities via an on screen keyboard There is also a facility to add pictures The menu also offered a stopwatch facility a scientific calculator a range of experiments and access to a periodic table display As an alternative the data was saved to a separate computer using the Multilab software and analysed there It is possible to connect the Nova 5000 direct to a printer without linking to a separate computer It is also possible to link directly to a projector or whiteboard In general t
57. ecessary Calibration is also affected at higher temperatures and highish humidities Response time was slow in still air but faster in moving air stream e g encouraged by a gentle fan Soil moisture This operates over 0 to about 45 moisture level by volume It should be used vertically to avoid making contact with a pool of water on or in the soil More accurate results are obtained if the soil is compacted to give good contact Investigation can clarify whether soil moisture content varies with depth No further calibration is required unless very high accuracy required Care was needed in removal from the soil to avoid damaging prong plates Sound This operates over a slightly wider range than many sound level meters covering 35 to 130 dB with an accuracy of 1 to 2 dB It also has a LCD panel enabling it to be used as a stand alone meter and a facility to switch between dBA and dBC weighting if this is required The high cost relative to other sound level devices reflects these wider options which may not be needed by many schools Stream flow As with other stream flow sensors the impeller comes with a four part rod for easier carriage and a 5 metre cable thus enabling the logger to be kept on the bank This sensor was not tested but has a range of 0 to 3 5 m s 44 Environmental Comment Parameter Temperature The basic TMP BTA model has a wid
58. eds and although not causing sunburn like UV B is believed to cause indirect DNA damage when it penetrates the skin The shorter wavelength UV B can cause sunbum or worse and is of direct danger to DNA Itis also emitted in electric arc welding and acetylene welding Damage to the outer parts of the eyes such as photokeratitis and conjunctivitis can also occur in strong direct sunlight in snowy conditions as well The condition known as snow blindness arises from this damage Protection for the eyes is therefore called for in these conditions or when carrying out welding and similar operations Weather forecasts frequently include reference to a UV index usually a number between 0 and 10 Table 7 overleaf indicates the sort of protection that is needed in each of these conditions Table 7 UV Description Index Sun Protection Required 0 2 Low e Minimal sun protection required for normal activity Wear sunglasses on bright days If outside for more than one hour cover up and use sunscreen Reflection off snow can nearly double UV strength Wear sunglasses and apply sunscreen 3 5 Moderate e Take precautions cover up wear a hat sunglasses and sunscreen especially if you will be outside for 30 minutes or more Look for shade near midday when the sun is strongest 6 7 High k Protection required UV radiation damages the skin and can cause sunburn Reduce time in the sun between 11 am and 4 pm and take fu
59. el presentation to display sensor collected data As noted in sections 2 3 and 5 this approach may reduce some of the costs but needs a laptop or other computer and has implications for the range of activities including remote logging which are possible Schools will need to decide how important this is and how far they wish to invest in new developments Age range over which the equipment will be used It is important that both staff and pupils feel confident in the use of the datalogger and the relevant sensors Some datalogger programmes have different levels of demand and complexity of presentation A school or college may plan to include environmental investigations in a number of different age or year groups Such a facility might therefore be beneficial and should be taken into account when final choices are being made Use of datalogging equipment by other disciplines in the school Other departments most obviously the geography department might also be using datalogging systems or wish to do so The possibility of joint purchase should therefore be at least considered though there are obvious potential snags to such an arrangement not least possible clashes in timing of use Some dataloggers have a wide variety of facilities built in so that other less obvious departments might well find them useful mathematics for example The use by other disciplines or departments in the school is also likely to affect the range of sensors require
60. er range than many such temperature probes covering 40 C to 135 C It has a stainless shaft and tip resistant to acids alkalis and salt solutions The resolution is 0 1 C over the most common range It gave a reasonably rapid response A similar version TPL BTA comes with a very long cable for remote measurements including temperature measurements below water in streams and lakes Vernier also produces an exposed thermistor sensor that gives a very rapid response for measurements e g for flexible situations or on skin It can be used only in air Ultraviolet Separate sensors are used to detect UVA 320 to 390 nm and UVB 290 to 320 nm Choice would depend on investigations to be conducted but probably UVB mainly associated with skin cancers and sunburn is more likely to be used Strictly calibration against radiation of known intensity and spectral distribution is needed probably pointing at the sun and setting at 100 is accurate enough Costs Sensor Supplier Catalogue number Cost Barometer air pressure IDS Granet BAR BTA 64 00 Carbon dioxide gas IDS Granet CO2 BTA 231 00 Colorimeter IDS Granet COL BTA 106 00 Conductivity adapter IDS Granet CON BTA 86 00 including electrode Dissolved oxygen probe IDS Granet DO BTA 190 00 Light sensor IDS Granet LS BTA 49 00 Oxygen gas sensor IDS Granet 02 BTA 174 00 pH sensor IDS Granet PH BTA 73 00 Relative humidity IDS Granet RH BTA 64 00 Soil moisture IDS
61. es in readings can then be related to differences in plant growth animal distribution etc Unfortunately this apparent simplicity is deceptive Traps for the unwary Plants absorb light most strongly in the red and blue parts of the visible spectrum a light meter may be most sensitive to light in the green region Animals may be influenced more by red infra red or ultra violet wavelengths light meters may not respond much to wavelengths at the extremes of the spectrum Most light sensors and meters that are now available measure in lux lumens m2 They have sometimes been designed for use by lighting engineers to measure light levels in offices etc where human perceptions of light are important Such lux meters typically have a response to the quality and quantity of light that matches that of the human eye with greater weightings for green wavelengths see the figure below which shows the spectral response of a typical light meter compared with the human eye They are not therefore ideal for fieldwork particularly for measuring light beneath trees Here red and blue wavelengths will have been absorbed by leaves with much green light remaining A lux meter will indicate higher light levels than are actually available for plants at ground level to use If the action spectrum of a typical plant showing the absorption of wavelengths by chlorophylls is compared with the response of a selenium cell used in many lux meters it is very eviden
62. ew other companies PASCO also produces a GPS position sensor that enables investigations of one parameter to be directly related to the location both sensors being plugged in to the Xplorer GLX simultaneously Some of these sensors are expensive but this full range should be taken into account when deciding about which logger and which sensors to buy 51 8 5 3 Pasco Datastudio software Compatibility Compatible with Windows 98 ME 2000 XP and VISTA and Mac OSX Licence Licences can be single user or site the latter being more expensive but the Lite version of the software is available from the web site free of charge Installation and operation The installation CD loaded easily on to a PC It made rapid and easy connection to the GLX and transfer of data from the logger to the PC was straightforward Downloaded data could be analysed as easily as on the GLX direct and equally environmental investigations could be controlled from the PC The CD included an interactive tutorial on which the sound level was very low making it difficult to hear The insertion of applause at response points proved irritating The menu offered the same range of facilities as on the GLX As before the sensors were instantly recognised on screen The menu offered the same range of continuous logging or individual readings e g at specific times Navigation around the options proved straightforward As before the frequency of d
63. fic thinking a Using scientific ideas and models to explain phenomena and developing them creatively to generate and test theories b Critically analysing and evaluating evidence from observations and experiments 3 2 Key processes e Practical and enquiry skills Pupils should be able to a use a variety of methods and techniques to develop and test ideas and explanations b assess risk and work safely in the laboratory field and workplace e Critical understanding of evidence Pupils should be able to a obtain record and analyse data from a wide range of primary and secondary sources including ICT sources and use their findings to provide evidence for scientific explanations Primary sources such as datalogging and secondary sources such as the Internet are essential aspects of pupils experience of science 2 3 Communication Pupils should be able to a use appropriate methods including ICT to communicate scientific information and contribute to presentations and discussions about scientific issues 3 4 The environment Earth and universe The study of science should include awareness that C human activity and natural processes can lead to changes in the environment 4 Curriculum opportunities The curriculum should provide opportunities for pupils to d study science in local national and global contexts and appreciate the connections between these g recognise the importance of sustainability in scientific
64. ficult to obtain precise values of a parameter than with a meter 5 4 Sensormeters or sensors linked to dataloggers As section 4 indicated changes to the National Curriculum and examination board syllabuses have led to a requirement to make increasing use of ICT in science work in schools and colleges This has resulted in a wider spread use of dataloggers in general and for exploring environmental factors in particular Take up has been inconsistent however Schools should therefore consider their current and future involvement in such ICT work across the science curriculum and possibly more widely in the school before investing in new apparatus whether it is to be meter based or sensor based Many meters cannot be used for datalogging though some provide a suitable output signal permitting connection to a separate datalogger Philip Harris for example developed a range of SensorMeters that provide the function of a meter and the capability to link to a logger in one unit such instruments obviously provide greater versatility However a meter may not be recognised by a given datalogger so the use of purpose built sensors will make the task of using the datalogger and accompanying software much more accessible and reliable Sensors designed specifically for use with dataloggers do not normally provide facilities for obtaining direct readings while in the field unless connected to a pocket book computer or a O 1 V voltmeter is atta
65. h a Logbook to generate Google Earth based visualisations of data from any Sciencescope sensor This enables a visual display showing a pictorial map of an area or journey with the level of say carbon monoxide or dioxide at different points 8 6 3 Sciencescope Datadisc Pt software Compatibility Compatible with Windows XP and VISTA though will probably work with 98 ME and 2000 Will also work with UNIX and Windows mobile Licence Sciencescope will negotiate a licence with the school Installation and operation Datadisc was readily accepted by the PC and automatically created a screen icon Logbook ML was then readily recognised when connected to the PC Datadisc offers three levels for working including one suitable for KS2 that has animated characters The menu offered the same range of normal continuous logging and snapshot logging On the GL roll capture which enables up to 12 seconds of data to be saved within a 2 minute window scroll graphed and stopped and saved on screen is also available The start icon operated logging which was tracked by a meter tabulated results or a graphical display on screen The graph autoscaled to accommodate the data collected Up to three parameters could be tracked on the same graph simultaneously though some pupils might find having two of the scales appearing to the right of the graph slightly confusing despite the use of three colours Collected data was readily saved
66. h the information in this guide is up to date at the time of writing given the rapid developments in microelectronics and computing schools and colleges should expect that some of the apparatus described may in future be changed for an improved or alternative model or discontinued Itis also possible that totally new approaches to datalogging might be developed It is also worth checking for possible discounts or special deals that may be offered by companies Always check with a range of various suppliers before placing an order CLEAPSS is very grateful to the companies concerned for the loan of equipment available to schools and colleges which is reviewed below and for their help with a number of issues arising It should be noted that there are a few other dataloggers that may be available for purchase but no samples were provided for the review Three aspects have been reviewed for each system the datalogger the sensors available some of which have been tested where they have been available and the software enabling links to be made to an external computer The following factors were used in our evaluation of the dataloggers and this may assist you in evaluating others Width height depth weight and availability of a carry case The physical dimensions of the datalogger and its weight will affect its portability Larger models will be harder to transport and will require more storage space Smaller models may be more awkward to o
67. he Nova 5000 EX also has extensive possible uses outside the science curriculum with a range of facilities such as word processing spreadsheets etc The BX and SX have modified software and cater for less demanding curricular needs The BX is classed as an entry level model whilst the SX is designed more for scientific use Fourier like other suppliers produces a series of books of experiment suggestions relevant to different aspects of science Each book comes with a CD version Whilst these are written for the American market many of the ideas could be adapted for local curriculum needs Fourier also offers the Ecolog XL with 5 built in sensors which is mainly aimed at primary work but might be suitable for some lower secondary work This machine was not available for testing Costs Supplier Catalogue number Price Fourier Nova 5000 EX 299 00 Nova 5000 SX 249 00 Nova 5000 BX 199 00 Newton Resources Nova 5000 EX 299 00 Excluding carriage 59 8 7 2 Fourier Sensors Environmental Parameter Comment Air pressure barometer The DT015 can be used as a pressure sensor and an altimeter as well as a means of measuring barometric pressure The range is 150 to 1150 mbar to an accuracy of 15 mbar Carbon dioxide The carbon dioxide sensor operates over a range of 0 to 5 000 ppm of carbon dioxide 10 The sensor consists of an infrared source and a detector and is base
68. hieved the toolbars displayed provide a fairly typical range of choices The main operational ones include Autolog in which readings are taken every 0 5 seconds for an indefinite period Logging settings in which it is possible to physically change the duration and frequency of readings and add graph titles Snapshot where time is not a variable and readings may be taken and labelled at the discretion of the observer Other options include Replay where the results can be reshown Repeat when another run can be carried out and Display options where choices can be made about the type of display required e g digital full screen etc A graph format toolbar is separately available giving options to display a graph plot with or without data points data points only a bar chart in vertical or horizontal mode a pie chart scales etc Option for interpretation of graphs obtained include the usual ones such as identification of values at given cursor points averaging smoothing of graph plots gradients at specified cursor points the area under a graph line etc Under test with a variety of sensors in place the screen flickered rather distractingly as each reading was recorded This is partly attributable to the Microsoft system The flicker was less intrusive at lower recording rates The graph autoscaled as the investigation proceeded and tabular information was presented on the screen simultaneously Use of a four way USB hub enables
69. ht could be useful in an environmental location However it is not designed to be resistant to corrosive liquids Protemp model DA61203 also 10 C to 110 C has a long stainless steel probe and can be used to measure temperature of soft soils as well There is also a version with a moulded extension lead Ultraviolet This model detects UVA and UVB radiation Whilst detailed tests would have been extremely time consuming the effect of cloud cover on the levels of UV followed expected patterns There is a wide range of possible investigations relating to effectiveness of sunscreen creams to UV output of e g light bulbs 38 Costs of Microsense sensors Sensor Supplier Catalogue number Cost Air pressure amp altitude Timstar DA61253 69 90 Beecroft WDA 03801 75 71 Griffin Education CRD 220 655X 69 90 Carbon dioxide gas Timstar DA71100 199 00 Griffin Education CRD130 730E 198 00 Colorimeter Timstar DA61294 79 00 Conductivity adapter Timstar DA61270 158 00 Ineluanojelectode Griffin Education CRD220 680P 158 00 Dissolved Oxygen Timstar DA61207 169 00 adapter and electrode Griffin Education CRD220 670S 169 00 Electrosmog Timstar DA71105 59 95 Griffin Education CRD130 740B 62 90 Light normal and Timstar SPX LUX DA61276 29 90 ouidogr USE General DA61271 15 90 Beecroft General WDA 02501 17 31 Lux WDA 02601 64 70 Commotion 12201 8 00 Griffin Ed
70. i a A gece 31 84 Werner LAD Quest E EE dar a svaaEA Aedo Nbb no tank seq land asa an SN aaa as S oa tuna aa ad 42 o co JAR cof 5 6 6 RCA NT RENAN RR IP RR ee es Mea ad RAR PR PRE RR 47 8 6 USCIENCESCOPE RENDA ese ete ie ee teed NR RP RR hee ee DR 53 8 7 Fourier Nova 5000 wa hide eel ete He ee Hie eee 58 8 8 ITECALIOJOSL sacarose a ie ii e dist A E ge fey Essa E EEE Austad ES pads ga 63 Appendix 1 Manufacturers and suppliers addresses eee 66 Strictly confidential circulation to Members and Associates only CLEAPSS 2009 CLEAPSS The Gardiner Building Brunel Science Park Kingston Lane Uxbridge UB8 3PQ Tel 01895 251496 Fax 01895 814372 R142 Equipment and Materials for Environmental Monitoring 1 General introduction A better understanding of the environment and climate and the impact of human activities has never been more important than now Concern in the past has often focused primarily on natural materials and energy resources available and accessible to mankind in order to sustain and improve life This remains an important issue not least because many of the resources of the earth are finite so effective and efficient recycling as well as further exploration for new sources has become a major area of development However a better understanding of the interactions between the Earth s atmosphere the seas lakes and rivers and plant and animal life and man s impact on them is now not just import
71. ide and more companies are entering the market As noted above even more recent is the introduction of the USB sensor and software which modifies Excel thus facilitating its use in analysing and presenting data collected via the sensors This section considers the background to deciding which of the different ways in which environmental measurements can be approached is best for your school Section 7 deals with specific factors that should be taken into account when deciding on a specific type of datalogger 5 1 Purpose built meters for measuring single or multiple environmental factors Independent meters are probably more familiar to many teachers and schools may have some of these in stock an important financial consideration Single purpose environmental meters have been around a long time and often have the advantage of being easy to use and relatively inexpensive Many of the advantages of single purpose individual meters also apply to dual purpose meters A meter able to monitor two or more parameters may be less expensive than the total cost of separate individual meters for making the same environmental measurements but flexibility in use by different pupils is also reduced Being able to measure say light as well as temperature may be a distraction for pupils when they only need to monitor one of these factors In addition multifunction scales on analogue multipurpose meters may confuse some pupils Temperature readings are also some
72. ily ignored whereas the constantly changing characters of a digital display especially one showing decimal figures can be very distracting Digital displays look modern are usually very easy to read and if the characters are large can be read by several students at the same time Digital meters are also more robust with less chance of damage if knocked or dropped They often permit greater resolution in measurements but this may not always be advantageous For example in monitoring pH changes measurements to two decimal places will be quite unnecessary teachers can of course blank off the last digit s with paint or tape Another disadvantage of digital meters with one or more decimal figures displayed is the impression of greater accuracy that may be conveyed this is often not deserved However this becomes a largely academic consideration if schools opt to use dataloggers on which the readings are digital 5 3 Meters or chemical test kits For some measurements of parameters in soil and water there may be a choice between the use of sensors meters or chemical test kits The latter may have certain advantages e g a test kit is less expensive than the equivalent sensor or meter or the chemistry involved may be of interest However replacement chemicals will be needed perhaps very regularly if the shelf life of the reagents is short Also because chemical test kits often rely on the subjective matching of colours it may be more dif
73. ing for straightforward logging operating for 50 seconds but the recording period and frequency of readings were easily altered to suit the investigation The start icon operated logging which was tracked by a meter or a graphical display on screen The graph autoscaled to accommodate the data collected Several runs were collected and displayed together Data may be tabulated analysed and displayed Analysis tools included graphing gradients differences area etc It proved straightforward to modify a table of data and to add notes on activities via an on screen keyboard As on the Nova 5000 there is a facility to add pictures The menu again offered a stopwatch facility a scientific calculator a range of experiments and access to a periodic table display Overall this software proved straightforward to use once installed 62 8 8 ITEC XLlogger 8 8 1 ITEC XLlogger The XLlogger came on to the market during the latter half of 2008 It is an entirely different approach to the other systems described above in that it does not need a logger at all It does however require use of a PC laptop or mini notebook into the USB port of which a USB sensor is plugged directly This has the advantage of saving the cost of buying a logger together with any licences required It should be noted that the software is relatively expensive although the price includes the appropriate licence Investigations in a laboratory can be conducted as normal
74. ion Black Box interface with CRD 960 020T 99 00 temperature and light sensor guide and software Timstar Black Box Interface DA71020 85 00 Timstar Also available with temperature DA71025 99 95 and light sensor guide and software 36 8 3 4 DCP loglT Microsense sensors The sensors discussed below can be used with a variety of logIT dataloggers except the Explorer A more limited range of sensors is available for the Explorer logger since its main use is in lower school work Environmental Parameter Comment Air pressure The DA61253 measures pressure in hPa covering range 800 to 1 100 hPa i e 80 to 110 kPa On testing results matched to other pressure readings with sufficient accuracy It can also act as an altimeter with a range of 500 m to 12 000 m This aspect was not tested Carbon dioxide One of the more expensive sensors the DA671100 uses non dispersive IR to measure carbon dioxide in ppm with a range of 0 to 2 000 3 ppm The cell must be kept water free It can be run by a power supply or via two AA batteries that are easily accessed The default frequency of readings is 2 per second though this can be adjusted A fairly heavy power usage is minimised by switching on only when readings are being taken It proved to be relatively easy to use and to follow readings The variation in readings seemed appropriate but more detailed testing would be needed to confirm their ac
75. its range is a general purpose thermometer Made of stainless steel the thermistor at the end is resistant to weak acids and is generally corrosion resistant The response was not very rapid but fast enough for most purposes Water should not be allowed to get into the PVC insulated cable Model 3101 also has a range 30 C to 110 C accurate to 0 3 C and is similar to the 3100 but the thermistor is unhoused allowing it to be used to measure temperature in small locations and confined spaces It can also be more easily attached to the body for biological measurements Likely to corrode if used with chemical solutions Ultraviolet The 3277 model is sensitive to both UVA and UVB radiation Six ranges are available from 0 to 50 Wm 2 up to 0 to 500 Wm 2 Whilst detailed tests would have been extremely time consuming the effect of cloud cover on the levels of UV followed expected patterns There is a wide range of possible investigations relating to effectiveness of sunscreen creams to UV output of e g light bulbs 28 Costs Sensor Supplier Catalogue number Cost Air pressure amp altitude Data Harvest 3140 49 00 Scientific amp Chemical DAT 060 720 49 00 Carbon dioxide gas Data Harvest 3152 199 00 Colorimeter Data Harvest 3275 69 00 Scientific amp Chemical DAT 060 840 69 00 Conductivity adapter Data Harvest 3135 29 00 Scientific amp Chemical DAT 060 740 29
76. jects start in 2009 The scientific study of environmental issues occurs to different extents in each suite of sciences produced by the examination boards Suffice to say that environmental issues are an essential aspect of most of these courses and the use of dataloggers sensors and appropriate software in collecting data analysing it and producing relevant charts and or graphs is made explicit GCE A and AS level Science subjects Similar expectations regarding the use of dataloggers sensors and relevant software apply to more advanced studies in biological and environmental science As before the precise wording varies from board to board and subject to subject 5 Choosing the right type of equipment There is a wide range of different kinds of resource for making environmental measurements This increases the difficulty in making correct choices in deciding what equipment to purchase For example it is possible to use a purpose built meter to study one specific environmental factor and a wide range of such meters is available Additionally some meters have multiple purposes thus enabling several environmental parameters to be studied with the same equipment It is no longer possible to easily purchase test centres that can be used to measure a number of different environmental variables Increasingly common in the field of environmental investigations are dataloggers used in conjunction with sensors The range of dataloggers is also quite w
77. k website www rapidonline co uk RM New Mill House 183 Milton Park Abingdon Oxfordshire OX14 5SE Tel 08450 700300 Fax 08450 700400 email secondarysales rm com website www rm com Sciencescope Abington House 146 London Road West Bath BA1 7DD Tel 0870 2256175 or 01225 850020 Fax 01225 850029 email sales auc co uk website www sciencescope co uk Scientific amp Chemical Supplies Carlton House Livingstone Road Bilston WV 14 0QZ Tel 01902 402402 Fax 01902 402434 email info scichem com website www scichem com TAG encompassing Economatics 25 Pelham Road Gravesend Kent DA11 OBR Tel 01474 357350 Fax 01474 537887 email sales taglearning com website www taglearning com Timstar Laboratory Suppliers Ltd Timstar House Marshfield Bank Herald Drive Crewe Cheshire CW2 8UY Tel 01270 250459 Fax 01270 250601 email sales timstar co uk website www timstar co uk TTS Group Ltd Park Lane Business Park Kirkby in Ashfield Nottinghamshire NG17 9LG Tel 0800 318686 Fax 0800 137525 email sales tts group co uk website www tts group co uk Vernier International See IDS Yorkshire Purchasing Organisation YPO 41 Industrial Park Wakefield Yorkshire WF2 0XE Tel 01924 824477 Fax 01924 834805 email sales ypo co uk website www ypo co uk
78. ld be suitable for most in door and outdoor environmental investigations It gave a reasonably rapid response 60 Costs Sensor Supplier Catalogue number Cost Barometer air pressure Fourier DT015 38 00 Newton Resources 0 1150 mbar 32 00 Carbon dioxide gas Fourier DT040 95 00 Newton Resources 99 00 Colorimeter sensor only Fourier DT185A 39 00 Newton Resources 39 00 Conductivity adapter Fourier DT035A 49 00 nC MeIng eevee Newton Resources 49 00 Light sensor Fourier DT009 1 22 00 DT009 4 25 00 Newton Resources 26 00 Oxygen dissolved oxygen Fourier DT222A 95 00 adapter And ciecvors Newton Resources 99 00 pH adapter and electrode Fourier DT016A 39 00 Newton Resources 49 00 Relative humidity Fourier DT014 29 00 Newton Resources 31 00 Soil moisture Fourier DT171A 49 00 Newton Resources 49 00 Sound Fourier DT320 46 00 Newton Resources 46 00 Stream flow rate Fourier DT254A 147 Temperature Fourier DT029 12 00 Newton Resources 14 00 There are a number of other sensors for the logger including a range of ion selective sensors suitable for water quality measurements and a turbidity sensor but many of the others are not relevant to a study of environmental factors Nevertheless the full range should be taken into account when deciding about which logger and which sensors to buy Fourier like some other suppliers offer bundles
79. ld though this is not the smallest or lightest logger available 47 Operation This datalogger can be used a stand alone device to record and display data or as an interface to another computer The top of the machine has four function buttons a five button keypad and an alphanumeric pad similar to that on a mobile phone The size of the screen is a distinct advantage by increasing visibility of experimental results Access is by an on off button and the home screen always returns using the house symbol on the keypad The twelve option screen this displays is readily navigated through the arrow keys The F1 to F4 buttons are short cuts to graphs tables a calculator and sensors If GLX is running just on the battery it will automatically save data and shut down after 5 minutes idling time If it is running on mains power and the battery is fully charged it will shut down after 60 minutes of idling time GLX will also sleep between samples if they are every 30 seconds or slower Sensors are easily connected via leads and the DIN plugs and are instantly auto recognised by the logger The start arrow commences continuous data collection from all connected sensors as default A manual sampling option at preferred time intervals and a triggered graphical start are options that may be set The home screen is the central feature of the GLX with 12 main icons and a top and lower bar These are readily navigated by the ar
80. lets or volume of chemicals used to reach an end point Items of apparatus selected for discussion in guide R142 have been chosen on the basis of their price their availability as indicated by their inclusion in catalogues of educational equipment suppliers their suitability or otherwise for use in the field and their availability for loan from suppliers More expensive items of equipment have not been included unless cheaper alternatives are not available Most modern dataloggers and many meters have been designed for use in both laboratory work and in the field The dataloggers tested can usually be operated using mains electrical supply or can be battery powered and can be taken out of doors for taking environmental measurements Batteries for such instruments will typically operate for a full day s work in the field without recharging With all battery powered instruments it is important to remove the batteries or cells from the equipment when not in use for an extended period of time and in storage 4 National curriculum and examination board requirements National Curriculum requirements The National Curriculum includes investigations of the environment and use of ICT in Key Stages 1 and 2 and subsequent work should be a further development of these early studies especially since many primary schools now use simple versions of dataloggers Specifically Science at Key Stage 2 refers to the following Sc1 Scientific enquiry Ideas and evi
81. ll precautions seek shade cover up wear a hat sunglasses and sunscreen 8 10 Very High e Extra precautions required unprotected skin will be damaged and can burn quickly Avoid the sun between 11 a m and 4 p m and take full precautions seek shade cover up wear a hat sunglasses and sunscreen 11 Extreme e Values of 11 or more are exceedingly rare in this country However the UV Index can reach 14 or more in the tropics and southern U S Take full precautions Unprotected skin will be damaged and can burn in minutes Avoid the sun between 11 a m and 4 p m cover up wear a hat sunglasses and sunscreen White sand and other bright surfaces reflect UV radiation and increase UV exposure Protection for the skin is now strongly recommended by health professionals and a variety of proprietary brands are available to meet different conditions Ingredients commonly used include titanium dioxide zinc oxide and avobenzone Sunscreen creams are normally classified by a Sunscreen Protection Factor SPF This is intended to indicate the level of protection against UV B radiation Table 8 illustrates this point Table 8 SPF Percentage of UV B absorbed 15 92 30 96 7 40 97 5 More recent research has raised questions about the length of time over which sunscreen protection against UV B remains effective and more investigation is needed A number of polymers have also been shown
82. more than one sensor to be used concurrently As each new sensor is inserted Microsoft automatically recognises it and requires driver installation Once the sensor has been used by the computer and the appropriate driver installation has taken place subsequent use is automatic When two sensors were plugged in to the hub it proved necessary to switch off Excel and reopen and to use the fresh start button to ensure that both sensors were identified The graph facility gave the option of having the y axis on the same side or on opposite sides of the graph Up to four sensors can be operated simultaneously and the results graphed but choices have to be made as to which axes are displayed Because a standard Microsoft system is used saving of experiment result files and transfer for example to pupils computers would be easy As noted above there are also advantages to the simplicity of the system but the need for a computer would limit use in the field Updates The system is new but as the software is updated the company intends to replace that held by existing users free of charge 64 8 8 3 ITEC Sensors Environmental Parameter Comment Gas pressure sensor A This is designed as a general pressure measuring device covering the range 100 kPa to 300 kPa On testing changes in external gas pressure were rapidly recorded and within anticipated ranges Light The XLS1033 operates over a full range of O to
83. nanccanoo 8 6 1 Measuring CONGUCTIVILY 0 cece cee eee eeee cer eaaeeaaeaaaeeaee ttt ttt EEE eaaeaaeeaaeeeaaeaaeeaaaeeees 8 6 2 Measuring MUMIGILY shade see cen cet tak sete atra aaia legiao succes Shun oneadoesh stuns laa Mat caeskusdeteuges ass canes 9 6 3 Measuring lighting posse dana ge iin A Be es Ge es 10 6 4 MeaSUNhg OX Ns sequestrar A a re ee eis ee ao 11 6 5 Measuring phases eaae a ara e a Taa ET a Giang ies a pa 12 6 6 Measuring soil water content and iOnS ssssssesssesesesseeeeierrirrrrtrrrrrrrrrrirrrrrrrerrrerrrerrrerrrerrnt 13 Br MeasSunrnog SOUNA ar hen ee eet ees oes Eeen ha eevee eee 13 6 8 Measuring temperature 00 i ll ll ll ill ini iia 14 6 9 Measuring water flow rate cece eeecenee cece cece eecaeeeeeeeeeesececeseaeeeeeeeeeeeseeaseeeeeeees 14 6 10 Measuring water pollutants 0 0 0 0 nil i i iin 15 6 11 Measuring ultraviolet radiation nine eee 15 6 12 Measuring aerial gases including carbon dioxide nitrogen dioxide and sulfur dioxide 17 7 Factors to consider when choosing systemS ee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee 18 8 Evaluation of equipment and materials esses 20 81 Philiptblarris Maris eloge ieee eases tulipas ats hac eaaa deter stateless 22 8 2 Datalharvest Easy Sense OQ caspa oaet ie get vhs De E A A anne ve RE Da DEAR DE eae 26 8 3 DEP LOGIT asma ros polia dia E suet Sie ct nnn dE ao EN a pa
84. nd the all purpose electrode 2251 Ag AgCl gel electrolyte The glass electrode attached to the end of a plastic body must be stored wet It must be rinsed with distilled water or the next test sample between tests as usual Depending on accuracy needed it can be used without further calibration but is better calibrated with standardised buffer solutions As with most pH electrodes there is a shelf life even if not much used Not extensively tested but worked effectively and with reasonable accuracy For very low conductivity solutions e g acid rain the electrode 2251 has a glass membrane stored in saturated KCI Not tested at this time Relative humidity This sensor measurement of the water vapour content relative to the ambient temperature 0 to 100 with an accuracy of about 2 to 5 depending on which part of the range is investigated The narrow end piece was found to be useful in reaching some small and awkward locations Obviously responsive to damp air the sensor must not be immersed in water Sound The 3175 model covers the 40 to 110 dBA range The sensor responded rapidly and gave sensible values in all conditions tested It also measures frequency content in mV As with most sensors it is not water resistant Temperature Three temperature sensors are produced but only two are likely to be used in environmental monitoring The 3100 has a range of 30 C to 110 C accurate to 0 3 C except at the ends of
85. o uk website www granetscience co uk Greater London Supplies GLS Fairway 1 Mollison Avenue Enfield Middlesex EN3 7XQ Tel 0845 1203213 Fax 0800 9172246 email sales glsed co uk website www glsed co uk Griffin Education Bishop Meadow Road Loughborough Leicestershire LE11 5RG Tel 01509 233344 Fax 01509 555200 email griffin fisher co uk website www griffineducation co uk IDS Instruments Direct Services Ltd Unit 8 The Courtyard Stenson Road Coalville Leicestershire LE67 4JP Tel 01530 832500 Fax 015300817087 email sales inds co uk website www inds co uk ITEC Ltd Holloway House Marlcliff Bidford on Avon Warwickshire B50 4NU Tel 01789 773537 Fax 01789 490832 email pgodding itec education co uk website www itec education co uk NES Arnold Gregory Street Hyde Cheshire SK14 4SG Tel 0845 120 4525 Fax 0800 328 0001 email enquiries nesarnold co uk website www nesarnold co uk Newton Resources Century House Station Road Sheffield Yorkshire S20 3GS Tel 0114 3240035 Fax 0114 3240025 email info newtonresources co uk website www newtonresources co uk Philip Harris Ltd Hyde Buildings Hyde Cheshire SK14 4SH Tel 0845 1204520 Fax 0800 1388881 email customerservice philipharris co uk website www philipharris co uk RapidElectronics SeverallsLane Colchester Essex CO4 5JS Tel 01206 751166 Fax 01206 751188 email sales rapidelec co u
86. ogue number Price Philip Harris B8L 11228 239 50 22 8 1 2 Harris e log IIS datalogger Width 186 mm at top 182 mm at bottom Height 126 mm Depth 40 mm Weight 643 g Memory 8 Mb i e double the e log II Screen size 73 mm by 55 mm slightly smaller than the e log II but still gives a reasonably clear picture Carry case Not made although Gratnell tray insert available Ports Top vertical face power 2 USB ports Front vertical face 4 small DIN ports for sensors 2 output ports Battery e log II S has a pair of lithium ion batteries These may be charged either from the mains or when connected directly to a computer Initial charging takes about 8 hours Fully charged the battery will last for about 8 hours in the field depending on the sensors used some sensors have higher electrical demand than others Wireless connection No facility for Bluetooth connection Manual Quickstart guides and user manuals are provided and are clear Upgrades Available through the Internet Field use Although not large the weight of the e log II S is greater than many other loggers Nevertheless carrying and use in the field as with the e log Il is not too difficult Operation Operation is very similar to the e log Il but navigation is controlled by a straightforward touch screen system Response time was reasonable but slightly slower
87. pare membranes electrolyte solution and bottle are included As with most oxygen sensors the process needs considerable time and care pH The DT016 has the usual 0 to 14 pH range accuracy 2 and includes both an egg shaped adapter and pH electrode at a very competitive price The sensor has a built in temperature compensation system The electrode maintenance and storage requires the usual precautions Relative humidity The DT014 covers the range of 0 to 100 relative humidity accuracy 5 at near room temperature The standard egg shaped case needs a separate lead to connect to the logger and is equipped with a zero offset screw Response rates for humidity sensors are often on the slow side but this modestly priced one was no slower than most Soil moisture DT171A is also a new addition and consists of a detector an adapter and a cable The soil moisture content is measured via a small cylindrical detector and ranges from 0 to 2 bar It was not tested Sound DT320 covers the usual range from 45 to 110 dB and gives a satisfactory response rate and sensible readings Stream flow DT 254A was not tested but is a relatively new model that has a telescopic handle and with the impeller housed in a protective cylinder Temperature The DT029 has a range of 25 C to 110 C accuracy of 1 C and plugs directly into the Nova 5000 The 130 mm metallic rod is resistant to mild chemical solutions and shou
88. perate and may be pocketed or mislaid by pupils A carry case will make transportation in the field easier help protect the unit during transport and may make it less likely for the unit to be mislaid or pocketed Memory If the datalogger is to be used in the field or remotely then it must be able to store the data collected More memory should translate into being able to store more readings meaning that the sample frequency can be increased or that the duration over which readings are taken can be increased Also the readings will need to be saved to computer less frequently Some dataloggers can save data direct to a memory stick whereas most need to be plugged into a computer to save the data Some have no memory at all and need to be attached to a computer to store captured data Screen size It is important that data displayed on the datalogger is clear and legible A large display with large characters is preferable for a demonstration model but data is typically transferred to a computer for display analysis and discussion back at school A larger screen is likely to deplete the battery more quickly Battery Battery life is a key factor in the use of a datalogger in general and particularly in remote use and use in the field Can it be easily recharged overnight Will the charge last all day out in the field Are the batteries custom or are they standard batteries that can be easily purchased 20 Ports The type and number of
89. phic light meter readings should be taken at a standard distance of light reflected off a grey card the blue cover of a paper copy of a CLEAPSS guide will be suitable for most purposes Light readings taken at a single moment may not reflect accurately the amount of light received by plants and animals because of broken or changing cloud cover The sun going behind a cloud may lead to a light level change of more than a factor of 10 for example Levels of irradiance increase and then decrease from morning to evening It is therefore important to take several readings at different times if possible This is a situation in which the use of a sensor and datalogger over an extended period is particularly valuable 6 4 Measuring oxygen Users of sensors or meters for measuring oxygen either in air or dissolved in water must be prepared to spend some time calibrating the instrument each time they wish to take a set of readings It may even be necessary to remake the electrode Although with care reasonable results can be obtained there are many factors that may interfere to produce difficulties Chemical methods of measuring dissolved oxygen levels although somewhat laborious to use can often give more reliable results For a discussion of chemical tests see section 17 2 3 of the Laboratory Handbook Chemical test kits provide an alternative See also the Recipe Card for Winkler s method Problems likely to be encountered An extensive
90. ports may be influential factors in the purchase of a datalogger How many sensors may be attached at once and therefore how many parameters may be read simultaneously Most connections to a computer will be via USB if only a serial connection is available then a serial to USB adapter s may need to be purchased and installed Wireless connection Typically dataloggers do not have a wireless connection Some models have Bluetooth for very short range transfer of data which is likely to be of limited use and is likely to drain battery life more quickly Some do have true wireless connectivity but provided the unit has enough memory then it is of little value unless you think that you may want to conduct a long term remote study Manuals and upgrades A good clear and comprehensive manual will be very helpful when it comes to setting up and using the datalogger Allow yourself sufficient time to read the manual carefully Software upgrades may be a mixed blessing they may provide additional functionality or fix problems with the software but are often an undesirable complication Weather proofing and field use General comment about how waterproof the unit may be and how portable and comfortable the unit is to use in the field Operation More detailed information about the functionality and use of the datalogger Sensors Details the range of sensors available for use with the particular datalogger Software Software is often the last
91. ps to resolve this Operation This datalogger can be used a stand alone device to record analyse and display data or as an interface to another computer Installation of the USB driver before charging from the CD supplied is easy and quick Navigation is by a four base joypad to the left of the screen The menu is easily navigated by the up and down buttons Power saving operates restart from any button The menu offers continuous logging individual readings e g at specific events or snapshot logging Sensors are easily connected via leads and are recognised by the logger Several sensors can be tracked at the same time Six of the toggle keys buttons to the right of the screen enable each channel to be displayed separately The remaining keys access the menu edit and zoom facilities Start and stop buttons operate logging that can be tracked by a meter or a graphical display The snapshot mode allows sensor readings to be captured on demand and now the data is readily stored in the memory There is a default setting for straightforward logging but the recording period and frequency of readings were easily altered to suit the investigation e g for very fast or much slower set of changes Up to 50 sets of experimental data can be stored in the Datavision memory Data may be saved to a separate computer using the logIT software 31 DCP also produces the logIT CX which is similar to the BX but has additional features in
92. pupil use and demonstration This can be a major issue when considering system purchase There are some significant variations in price between models considered Clearly if a datalogger and sensors are mainly intended for demonstration purposes then a more sophisticated more expensive model might be preferable However if much of the work is likely to be done in the field then a larger number of less expensive models may be the preferred choice The location of work in the laboratory Where investigations are to be laboratory based it is essential that an appropriate range of services is available in the laboratory for the usage planned So if work is to be carried out by pupils electrical points and all other facilities relevant to the investigation including possible access to a computer must be suitably located If the investigation is to be done by demonstration the laboratory must not only have suitable services and other facilities such as projection but also appropriate visibility to all pupils observing It is worth reiterating that schools should discuss possible purchase with representatives and suppliers before taking decisions Further where possible trial packages should be evaluated in the school situation by staff and pupils concerned 19 8 Evaluation of equipment and materials The ranges and sophistication of electronic equipment on the market for monitoring environmental parameters are continually changing Althoug
93. r licence Further multi user licences available Installation and operation The CD was readily accepted by the computer but recognition of the Easy Sense Q Advanced was not found to be quite so straightforward Clearer guidance would have been helpful Opening screen offers a range of icons Home being the main navigation window Home offers a good range of new experiment options Easy log graph meter scope snapshot timing etc The Easy log proved straightforward amp gave a line graph auto scaling until stopped manually As with the stand alone logger it proved easy to adjust the duration and frequency of readings from sensors connected and to achieve different graphical formats Other facilities included overlaying several runs smoothing tools measurement of gradient and area under the graph curve Enhancement of presentation of graphs to include headers table graph description labels etc was also available The Home icon also offers a number of options open file open worksheet open set up set up remote and retrieve records Data Harvest produces a very extensive range of books of experiments and work sheets relating to datalogging in the sciences designed to match ages 9 to 14 and 14 to 18 Each comes with a CD The older range has been produced to reflect changes to GCSE requirements Whilst by the very fact of production they appear prescriptive teachers are able to modify to their own pupils needs and
94. range 0 1 to 70 V m with a resolution of 1 There is also an advanced model S1851 which is more sensitive to lower emission levels Light The advanced S1862 operated over the range almost 0 to 100 000 lux resolution 2 It has a fast and a slow auto response enabling measurements to be taken at low and high light levels including full sun The response rate was satisfactory For many school activities the cheaper S1074 can be used to measure a wide range of light levels giving readings in log lux resolution 5 Accuracy is clearly not as great Nitrogen dioxide The S1695 is a neat self contained sensor designed to detect nitrogen dioxide in the range 0 to 10 ppm resolution 0 1 ppm Tests were carried out comparing levels in parkland and near a busy road and sensible readings were obtained to show the differences Oxygen dissolved The S1899 has an integrated oxygen probe and the built in electronics provides temperature compensation over a range of 0 C to 50 C The range is 0 to 20 mg dm of dissolved oxygen It was not tested Oxygen gas The S1770 has a range of O to 30 resolution 0 1 The oxygen cell itself should last for at least a year and a replacement cell can be purchased It was not tested pH The basic probe S1865 covers the pH range of 0 to 14 and can be calibrated with Datadisc This model comes with an attached pH probe but the storage and maintenance regime remains as important as ever E
95. ransfer of data to a computer no more than connection 10 metres away Bluetooth models weren t tested but have greater battery demand Manual Comes with straightforward user manual and Easy Sense quick start guide Upgrades Software updates are available from the Data Harvest website Weather No datalogger is waterproof In the field users are advised to store in a plastic or other proofing protective box Field use The relatively limited size and weight make it fairly easy to use in the field Operation This datalogger can be used a stand alone device to record display and graph data or as an interface to another computer Installation of the USB driver from CD supplied before charging is easy and quick Navigation is by a four base keypad The main menu start screen gives a choice of three levels for secondary pupils level 2 or 3 should be used The menu is easily navigated by the up and down buttons Power saving operates after 2 minutes without use longer for the Bluetooth model The menu offers easy log meter snapshot logging time amp motion unlikely to be used in environmental work and system plus switch off Sensors are easily connected via leads both short and long supplied and are recognised by the logger Several sensors can be tracked at the same time some interference is evident with a pH and an oxygen sensor together In meter mode readings are taken every half a second but no data is stored
96. re easily replaced through back of logger using screwdriver provided Can also be run from a computer via a USB connection The battery life in field use depends on which sensors are being used but should be at least 12 months Wireless connection The SX has no wireless facility but the SX AIR ONE is Bluetooth enabled Manual This comes with a guide including suggested activities Upgrades Software updates are available from website Weather proofing No datalogger is waterproof Voyager comes in a hard carry case which offers some protection Field use The design with a hand grip and the relatively light weight makes use in the field relatively easy Operation This datalogger can be used a stand alone device to display investigation results as they happen or as an interface to a computer Installation of the USB driver from CD supplied before charging is easy and quick A three button navigation pad makes manipulation very simple Power saving operates restart is from any button Can be used for continuous logging displaying values usually determined by the sensor inserted This can also be altered using the button and selecting from the options open for that sensor An autolog setting enabled readings to be taken both for immediate usage and for remote longer term work The frequency of readings was rapid to start with but extended to longer periods when the logger was left for a period of
97. readings were easily altered to suit the investigation Data was tabulated analysed and displayed Zoom in and out graph analysis including tangent drawing integration to obtain areas under graph lines etc were all options As before there were facilities to modify the table of data and to add notes on activities and to add pictures Overall this package proved straightforward to use 46 8 5 Pasco 8 5 1 Pasco Xplorer GLX Feedback Instruments Width 100 mm at widest Height 228 mm Depth 50 mm including feet Weight 528 g Memory 12 MB of data storage which can be enhanced using a flash drive memory stick Screen size 78 mm by 60 mm This is large enough to give a clear visual display Carry case A field bag or solid carry case is available to hold the Xplorer portable keyboard mouse small probes etc Top vertical face 4 DIN sensor ports Ports Right hand vertical face 2 USB ports one to connect to a mouse mobile keyboard printer or flash drive etc and one to link to PC etc and power jack point Left hand vertical face has 2 built in temperature probes voltage port and signal output port There is also a built in sound sensor and a speaker for sound output at the bottom of the top face Battery Rechargeable NiMH battery from the mains or it can be run from a computer when connected Initial charging takes about 14 hours The battery should last abo
98. rested further information is given in section 17 2 1 of the Laboratory Handbook Much more convenient is the use of carbon dioxide sensors The nature of the investigations will depend on the range of the enquiry for example the variation of carbon dioxide content in air near busy traffic laden roundabouts compared with open country motorways or side roads Some useful and interesting investigations can be done by linking GPS tracking with carbon dioxide monitoring The variation in the carbon dioxide content in air in a classroom or other area over time can be studied as can the change in the levels of carbon dioxide in fermentation processes or in the growth of plants Carbon dioxide sensors often have a high and a low setting which permit readings approximately in the ranges of 0 to 10 000 or 0 to 100 000 PPM Many sensors work on monitoring the amount of infrared radiation absorbed by the carbon dioxide molecules Calibration of such sensors is not usually necessary but they may be sensitive to temperature changes although they normally operate reasonably accurately between 20 C and 30 C Nitrogen dioxide is produced in vehicle engine emission within a mixture of nitrogen monoxide nitric oxide and nitrogen dioxide often depicted as NOx These are both toxic and can give rise to asthma attacks in susceptible people They are a major contributor to acid rain and photochemical smog A nitrogen dioxide sensor can be used in studies of variations in
99. row keypad or a mouse if one is connected All sensors connected are located on the sensors screen and the frequency of data sample collection altered for continuous logging Each sensor can be adjusted individually The frequency of manual sampling is determined by the operator options ranging from 200 per second to one per 4 hours It is also possible to either display the data collected from a given sensor on the screen or hide it Data display can be graphical tabulated or meter Up to two graph lines can be displayed at a time using black and grey to distinguish and with a y axis at each side of the graph Saving of data is straightforward Analysis tools then include graph smoothing autoscaling zoom selection of graph sections gradients differences area linear fit etc It also proved straightforward to modify the table of data and to add notes on activities via the keyboard Data may also be tabulated analysed and graphically displayed after transfer to a PC using the Datastudio software The extensive calculator functions are accessible from the keypad and include basic mathematical calculations algebraic calculations and graphical ones as well as the sensor based ones A comprehensive GLX Users guide was provided This proved to be clear and reasonably easy to understand A tutorial CD Users guide to stand alone datalogger activities for the GLX was also available but the sound level was too low for easy use Otherwise i
100. s addresses Beecroft amp Partners Ltd Northfield Road Rotherham South Yorkshire S60 1RR Tel 01709 377881 Fax 01709 369264 email sales beecroft science co uk website www beecroft science co uk The Consortium Hammond Way Trowbridge Wiltshire BA14 8RR Tel 0845 33097780 Fax 0845 3307785 email enquiries theconsortium co uk website www theconsortium co uk Datadisc See Sciencescope Data Harvest Group Ltd 1 Eden Court Leighton Buzzard Bedfordshire LU7 4FY Tel 01525 373666 Fax 01525 851638 email sales data harvest co uk website www data harvest co uk DCP Microdevelopments Ltd Bryon Court Bow Street Great Ellingham Norfolk NR17 1JB Tel 01953 457800 Fax 01953 457888 email info dcpmicro com website www dcpmicro com Feedback Instruments Ltd Park Road Crowborough East Sussex TN6 2QR Tel 01892 653322 Fax 01892 663719 email sales fdbk co uk website www fbk co uk 66 Fisher Scientific Bishop Meadow Road Loughborough Leicestershire LE11 5RG Tel 01509 231166 Fax 01509 231893 email sales fisher co uk website www fisher co uk Fourier Systems UK Ltd PO Box 402 Maghull Business Centre Red Lion Building Liverpool Road North Maghull L31 2HB Tel 0845 434 7934 Fax email ukinfo fourier sys com website www fourier sys co uk Granet Science PO Box 404 Aylesbury Buckinghamshire HP19 9WD Tel 01296 398624 Fax 01296 426507 email sales granetscience c
101. sell sensor packs which may be worth investigating if a school is looking to purchase a range of sensors at one time Costs of Explorer sensors Sensor Supplier Catalogue number Cost pH Beecroft WDA 00305 85 45 Commotion 12461 70 00 Griffin Education CRD 650 020E 69 99 NES Arnold 04BJ72623 119 95 Temperature Beecroft WDA 00304 21 63 Commotion 12460 19 99 Griffin Education CRD 650 010H 20 00 NES Arnold 04BJ72625 49 95 40 8 3 5 DCP LoglT Lab 4 software Compatibility Compatible with Windows 95 98 NT XP and is VISTA compliant Licence LoglT comes with single user licence but multi user Site licences are available However it should be noted that each different logger model has a different licence Installation and operation The CD was readily accepted by the computer and recognition of the LoglT was quite straightforward The opening screen offers a range of 4 levels of sophistication the Advanced being the most appropriate for secondary working The software autodetects sensors linked to the logger and as with the stand alone logger there is a choice of autolog or manual adjustment and as before it proved easy to adjust the duration and frequency of readings from sensor s connected There was a choice of snapshot or continuous readings Control of investigations was as straightforward as with the stand alone logger The advanced setting of LoglT Lab offers
102. sensor Access is by a start button and navigation The screen dims if not used but though there is no short term power saving this will kick in if Labquest has not been used for some time Sensors are easily connected via leads and are instantly recognised by the logger Several sensors can be tracked at the same time The remaining keys access the menu edit and zoom facilities The touch screen is operated by a stylus and gave a rapid response The menu offers continuous logging individual readings e g at specific events or snapshot logging The start button operates logging that can be tracked by a meter ora graphical display on the good sized screen The graph autoscaled where necessary to accommodate the data collected Several runs may be collected and displayed together if required Snapshot mode allows sensor readings to be captured on demand and now the data is readily stored in the memory There is a default setting for straightforward logging but the recording period and frequency of readings were easily altered to suit the investigation e g for very fast or much slower set of changes Up to 50 sets of experimental data can be stored in the memory Data may be tabulated analysed and displayed It proved straightforward to modify the table of data and to add notes on activities via an on screen keyboard There is also a facility to add pictures The menu also offered a stopwatch facility a scientific calculator a range of
103. sorbance and reports both simultaneously Autocalibration is readily achieved with a cuvette of clear water Wavelengths covered are 660 nm 610 nm 565 nm and 468 nm giving a good spectral range Conductivity PS2116A comes with a sensor box and conductivity probe It has three ranges 0 to 1 000 uS cm O to 10 000 uS cm and O to 100 000 uS cm accuracy improves from about 10 reading to 0 1 after calibration The glass bulb is well protected within the probe Instructions for calibration are given but a standard solution of known conductivity is required This is useful to compare the conductivity of different water samples Spare probes are available Humidity The PS2124 was not tested but is designed to measure relative and absolute humidity 0 to 100 2 dew point 50 C to 50 C 0 5 and temperature 20 C to 55 C 2 C Light The PS2106A is a very flexible sensor with three different ranges 0 to 2 6 lux O to 260 lux and O to 26 000 lux enabling it to be used a in a wide variety of situations The sensor automatically indicated when a different range is more appropriate The response to changes in light intensity was rapid There are other sensors which include light as part of a multiple parameter device such as PS2140 temperature sound light and the PS2168 general science sensor temperature light sound voltage Oxygen dissolved The PS2108 was not tested It is quite expensive The r
104. sponse to all frequencies Sound is also measured in other sensors as part of a multiple parameter device such as PS2140 temperature sound light and the PS2168 general science sensor temperature light sound voltage Stream flow rate The PS2130 was not tested It consists of an encased impeller with the usual range of 0 to 3 5 m s The telescopic handle extends to 6 feet giving a good range to reach into deeper water safely A built in thermometer indicates temperature at the depth of flow rate measurement Temperature The range of thermometers includes the PS2125 which has a stainless steel probe that is reasonably resistant to attack from many solutions The range of 35 C to 135 C accuracy 0 5 C is wider than most similar devices and the response is rapid There is a wide range of temperature measuring devices for specialist situations e g skin surface and as part of a multiple parameter sensor such as PS2140 temperature sound light and PS2147 pH temperature ORP ISE and the PS2168 general science sensor temperature light sound voltage Thermocline Although not tested the PS2151 offers the ability to measure temperature as a function of water depth with an extensive depth range of O to 10 5m and a temperature sensor over the range 0 C to 100 C A weighted cable is designed to give more reliable depth measure The cost may encourage schools to opt for a simpler way of inve
105. stigating the relationship between depth and temperature Ultraviolet The PS2149 was not tested but measures UVA band radiation and extends into the visible range using a photodiode sensing element a filter and collimator 50 Costs Sensor Supplier Catalogue number Cost Barometer Feedback PS 2113A 80 00 air pressure Carbon dioxide gas Feedback PS 2110 224 00 Colorimeter Feedback PS 2121 107 00 Conductivity adapter Feedback PS 2116A 89 00 including electrode General science Feedback PS 2168 134 00 Humidity Feedback PS 2124 71 00 Light sensor Feedback PS 2106A 53 00 Oxygen dissolved oxygen Feedback PS 2108 197 00 adapter and electrode Oxygen gas Feedback PS 2126 170 00 pH temperature ISE ORP Feedback PS 2147 104 00 pH sensor and electrode Feedback PS 2102 71 00 Sound Feedback PS 2109 89 00 Stream flow rate Feedback PS 2130 116 00 Temperature Feedback PS 2125 26 00 Temperature sound light Feedback PS 2140 80 00 Thermocline Feedback PS 2151 233 00 Ultraviolet Feedback PS 2149 143 00 Pasco offers an extremely wide range of sensors This range includes a number which would be useful for other aspects of environmentally related work than those detailed above including several water quality sensors a weather sensor which measures a range of parameters in one instrument and a turbidity sensor As with a f
106. sun gave a suitably fast and appropriate response Costs Sensor Supplier Catalogue number Cost Barometer Sciencescope 2005 85 00 air pressure Carbon dioxide gas Sciencescope 1853 100 00 Conductivity Sciencescope 2004 120 00 incorporating probe Electrosmog basic Sciencescope 1850 35 00 Light sensor general Sciencescope 1074 20 00 advanced 1862 45 00 Nitrogen dioxide Sciencescope 1695 150 00 Oxygen dissolved Sciencescope 1899 150 00 Oxygen gas Sciencescope 1770 120 00 p probe Sciencescope 1865 60 00 Relative humidity Sciencescope 1867 45 00 Sound Sciencescope 1843 30 00 Stream flow rate Sciencescope 1699 200 00 Temperature Sciencescope 1698 20 00 Ultra violet Sciencescope 1869 65 00 56 There are a number of other sensors for the logger including a range of relatively costly ion selective sensors suitable for water quality measurements and air pollution gases such as sulfur dioxide and carbon monoxide but many of the others are not relevant to a study of environmental factors Nevertheless the full range should be taken into account when deciding about which logger and which sensors to buy Sciencescope also produces a colorimeter looking like a version of the Logbook which can be used as a stand alone device or connected to a datalogger 31647 Sciencescope has also introduced a Garmin etrex location monitoring device 31312 which combines a GPS unit wit
107. t proved to be a helpful support to the layout of the GLX and to its range of facilities Pasco also makes the simpler smaller and cheaper Xplorer datalogger Inevitably this has fewer functions and is more limited in its capability but may be worth consideration for certain circumstances Costs Supplier Catalogue number Price Feedback Instruments Xplorer GLX including PS 2002 283 00 Datastudio Lite software and 2 stainless steel temperature probes 48 8 5 2 Pasport Sensors Connection of the neat sensors in each case is via a small DIN plug Pasco produces a larger number of multiple parameter sensors than most suppliers e g temperature sound light Environmental Parameter Comment Air pressure barometer The PS2113A has ranges of 150 to 1090 mbar and 15 to 109 hPa and is quite sensitive enabling for example changes in air pressure from floor to ceiling in a room Carbon dioxide The PS2110 is quite expensive It comes with a probe and 250 ml sampling bottle and bung It has a range of 0 to 300 000 ppm with an accuracy of about 10 thus offering a wide range of uses Further calibration should not be required but over time may prove necessary and clear directions are given Use is straightforward but time was needed for the sensor to warm up even at room temperature Colorimeter The PS2121 colorimeter was not tested It has the usual range of 0 to 100 transmittance and 0 to 3 ab
108. t should not be used in corrosive especially acidic solutions Costs Sensor Supplier Catalogue number Cost Air pressure ITEC XLS1032 72 35 Light sensor ITEC XLS1033 37 44 Oxygen gas ITEC XLS 1047 99 45 pH sensor ITEC XLS1005 72 35 Relative humidity ITEC XLS1008 62 01 Sound ITEC XLS1013 38 03 Temperature ITEC XLS1001 28 67 There are a number of other sensors for the system though the range is not yet as extensive as more established systems Most of the other sensors available at the time of writing are not relevant to a study of environmental factors Nevertheless the full range should be taken into account when making decisions about which system and which sensors to buy ITEC has a number of other sensors under development some of which would be relevant to environmental investigations including carbon dioxide dissolved oxygen and a colorimeter 65 After purchase support for all logging systems As with all new equipment or equipment which is new to the teacher spending time with the instruction leaflet the loggers the software and the sensors is essential Whilst there are similarities between models from different companies there are usually some very different characteristics as well Most of the suppliers will provide some post purchase training which may be free but may be charged for All offer post purchase support which is reportedly very helpful Appendix 1 Manufacturers and supplier
109. t that readings with such a light meter in relation to a plant s ability to photosynthesise must be interpreted with care Selenium cell Lux meter 400 100 F Human eye Leaf action spectru Response Absorption 50 F 50 1 1 1 1 1 1 fi fi f 1 1 1 300 400 500 600 700 400 500 600 700 BLUE GREEN RED BLUE GREEN RED Wavelength in nm Wavelength in nm Light levels can vary enormously by a factor of 100 000 In order to cope with this wide variation most sensors use a logarithmic scale so that an output increase of say 0 2 volts could represent a tenfold increase in light level Instruments which measure total radiant energy irradiance units watts m have a more even response across the spectrum but they are unfortunately too expensive for normal school use and have limitations for fieldwork too Many suppliers offer sensors that focus on a particular light range but most have an all purpose light or lux sensor that may cover a range of say O to 100 000 lux which may cover a spectral range of 400 to perhaps 1 100 nm Note that photographic light meters use a logarithmic scale with no apparent units and indicate the aperture or f number for exposure of film It is possible to convert such readings roughly to lux or W m see Table 17 6 in the Laboratory Handbook Note too that an increase in exposure of one stop or exposure value represents a halving of illumination When using a photogra
110. t the costs to those associated with the software and the USB sensors At present only a limited range of sensors is available though this will probably be expanded The requirement to link the sensors to a PC laptop or mini notebook also limits the range of activities that can be carried out and would make remote datalogging extremely difficult 5 6 Reliability and ease of use Monitoring equipment ideally should be able to give accurate readings quickly with the minimum of fuss every time it is used Sensors for many parameters work quickly and without problems Unfortunately sensors used for the measurement of some parameters including conductivity pH and oxygen often require calibration either before the instrument meter or sensor is taken outside or even in use in the field The maintenance of electrodes between tests to keep them in good working order must also be considered The battery compartment of some environmental meters is easily accessible usually just by sliding back a plastic cover This ready accessibility may be a disadvantage for work with some pupils an increasing number of meters have batteries that can only be reached by unscrewing a cover Pupil accessibility of pre set calibration controls may also be a problem and some meters have been designed with this potential problem in mind 6 Measuring environmental parameters 6 1 Measuring conductivity Measurements of the conductivity of water samples can give an indica
111. ted that the terminals of a galvanic electrode must be shorted together when not in use to prevent a build up of oxygen in the electrolyte After being remade a galvanic electrode will need to be reconditioned to remove internal oxygen by storing in 3 or 6 sodium sulfite solution for 6 hours before use Storage of oxygen sensors probes The electrolyte must be replenished at regular intervals The cathode tip must not be scratched and the membrane must be kept intact It is not feasible to use an electrode for measurements at depth The best arrangement is to collect water in a device as illustrated in section 17 2 3 of the Handbook and to take measurements immediately once the water samples have been brought to the surface 11 6 5 Measuring pH Discussion of the use of pH meters and electrodes is given in section 17 3 9 of the Laboratory Handbook Most of this applies equally to sensors There is also useful information in guide R35 pH Measurement There are however specific matters that relate to fieldwork that must be considered Problems of measuring pH in the field pH measurements made in the lab are normally performed on reasonably concentrated solutions which have some natural buffering action they are not unduly changed in pH by contamination with impurities or by indicators used Water samples particularly if quite pure will not behave like this and a slight impurity can change the pH reading significantly Indicators th
112. ties involved in using pH meters for field measurements the use of indicator solutions and papers may often be less problematical though the indicator itself may affect the readings obtained Indicator solution is commonly used for soil and water pH measurements and there are a number of kits available For pH measurements in water indicator paper strips must be left in place for a long time to obtain accurate results and the indicator tends to be leached out of the paper unless the non bleeding type is used 6 6 Measuring soil water content and ions See section 6 5 for a discussion of measuring soil pH A suitable sensor may be used when carrying out investigations such as bottle biological experiments or the loss of soil moisture by evaporation or the evaluation of the optimum moisture content for growing various species Such investigations are based on measurement of the volumetric water content of soil In simple terms dry soil is made up of minerals and pockets of air When soil becomes wet or even damp then water starts to fill the air pockets The volumetric water content will thus be limited by the volume of the air pockets or pores Soil moisture sensors do not usually need to be calibrated especially where it is essentially relative values that are required This may not apply when very accurate values are required or the soil has a high sand salt or organic content Calibration is then usually carried out using either a two point or the
113. time The logging rate can also be set via the three keys Sensors easily connected via leads amp were auto recognised by the logger The screen though small was clear The saved data can easily be transferred to a separate computer using the logIT software and analysed and presented in required graphical or other format 33 DCP also makes the logIT Explorer which is designed for primary and middle schools and is probably suitable for use up to the end of KS3 It therefore overlaps in use with the Voyager The size shape and weight is similar to the Voyager but it has the advantage of built in light temperature and sound sensors There is also a jackplug facility for connecting a different sensor which could then over ride the in built one However sensors designed for use with Datavision or the Voyager cannot be used with the Explorer directly As with the Voyager a USB connection enables data to be transferred to a computer and analysed and displayed Costs Supplier Catalogue number Price Griffin Education Voyager SX includes logger CRD 550 010P 199 00 temperature sensor and software manual etc Griffin Education Voyager SX Air includes CRD 550 S 249 00 Bluetooth enabled logger temperature sensor and software manual etc Rapid Voyager SX includes logger 85 2681 191 00 temperature sensor and software manual etc TAG Learning Voyager SX Voyager SX 199 00 Timstar Vo
114. times included as an additional feature on meters for parameters such as pH relative humidity or conductivity in which automatic temperature compensation is built in In many cases however a separate environmental thermometer unit will still be needed because of the absence of a suitable probe for measuring temperature Nevertheless should a school decide that individual meters are the best approach it may be helpful to know that CLEAPSS has produced guides on a number of single purpose meters including pH meters conductivity meters ammeters and voltmeters colorimeters and so on in recent years 5 2 Analogue or digital meters Analogue meters with a needle moving over a scale may be difficult for some students to read and depending on the length of the scale may not be able to give readings with as great a resolution as the display of a digital meter They may also be perceived by students as low tech equipment Nevertheless for parameters that vary over a wide range an analogue meter often gives a clearer visual impression of the extent of the changes that are being measured For example if a digital meter gives readings of a parameter of 0 45 and 0 89 units pupils may not see that the measurement has doubled as clearly as they might with a pointer moving twice as far over a scale Also for situations in which readings with small continuous fluctuations are obtained the slight movement of the needle on an analogue meter is often eas
115. tion of their purity or more appropriately the level of dissolved substances in the water The greater the quantity of substances dissolved in a water sample the higher the sample s conductivity reading Conductivity measurements do not however give any clue to the identity of the dissolved substances In sea water readings will usually indicate salinity in unpolluted water an indication of water hardness may be obtained from conductivity measurements The conductivity of soils might also provide an indication of levels of soluble nutrient ions that are present Measurements in a river might indicate the level of pollution but it is impossible to differentiate between pollutants and naturally occurring substances Thus a comparison of conductivity readings obtained from two separate bodies of water will not always reveal meaningful information Variations could merely reflect the different nature of the underlying substrate over which the waters flow and hence differences in the nature of the ions that are dissolved in the water However if readings are made using water samples taken for example at different positions along the length of a stream then rapid changes in conductivity might be used to locate the source of an outflow of chemicals Units of measurement Conductivity sensors or meters often give readings in the preferred units S cm usually uS or mS S siemens but O cm O ohms may be used Occasionally reference may be ma
116. to degrade on exposure to UV radiation and antique paintings may also be discoloured Clearly there is much scope for environmental monitoring and investigation in this area Most sensors used to detect UV radiation available at acceptable prices to schools are designed to measure either UV A or UV B but quite often both together Further information is included in Students Safety Sheets 6 12 Measuring aerial gases including carbon dioxide nitrogen dioxide and sulfur dioxide Much emphasis has been placed on the role of carbon dioxide and other aerial gases in global warming so environmental monitoring in schools and colleges is likely to give some emphasis to their study The average concentration of atmospheric carbon dioxide over the past 40 or so years has increased from about 320 PPM to over 380 PPM though figures are likely to be higher in localities close to areas of high emissions such as major roads or roundabouts Carbon dioxide can absorb increasing amounts of infrared radiation and is thus able to act as one of the so called greenhouse gases gradually contributing to a raising of atmospheric temperatures The carbon dioxide content in air samples may be quantitatively investigated using chemical methods This involves absorbing the carbon dioxide in an air sample in concentrated potassium hydroxide and titrating against barium hydroxide solution This can be a lengthy and potentially hazardous procedure but for those inte
117. ucation General CRD130 512X 15 90 LUX CRD130 625B 59 90 SPX LUX CRD130 627U 29 90 pH amplifier and Timstar DA61206 79 90 clecttage Timstar adapter DA61282 6 00 Beecroft WDA02801 92 43 WDA02802 43 26 Commotion 12215 40 00 electrode only Griffin Education CRDF130 554V 79 90 Rapid 85 2618 77 20 RM QJM 918 66 49 Relative humidity Timstar Humipro DA61267 98 00 General DA61265 75 00 Beecroft WDA 03301 81 08 Griffin Education General CRD130 630Y 75 00 Humipro CRD220 645R 98 00 Sound Timstar DA61205 39 90 Beecroft WDA 03201 43 26 Commotion 12080 40 00 Griffin Education CRD130 585K 39 90 Rapid 85 2612 38 55 Sensor Supplier Catalogue number Cost Stream flow Timstar DA61281 149 90 Beecroft WDA 03401 162 24 Griffin Education CRD130 750V 149 90 Temperature Timstar Protemp DA61203 24 80 Hitemp DA61272 15 90 Beecroft Protemp WDA 02201 27 04 Commotion Protemp 12073 15 00 Hitemp 12071 16 00 Griffin Education Protemp CRD130 570A 24 90 Hitemp CRD130 506J 15 90 Rapid Protemp 85 2608 24 10 Hitemp 85 2606 15 35 Ultra violet Timstar DA61285 95 00 Griffin Education CRD130 755L 95 00 Rapid 85 2685 92 00 There are a number of other sensors for the logger but they are not relevant to a study of environmental factors but the full range should be taken into account when deciding about which logger and which sensors to buy Several companies
118. uctivity This sensor requires both the adapter and the conductivity electrode 3136 In contrast to the pH electrode this one can be stored dry There are four ranges 0 to 100 mS 0 to 1 mS 0 to 10 mS and 0 to 100 mS thus permitting work from low ionic concentrations acid rain to highly conducting solutions e g sea water Data harvest recommend that for much work the default calibration would be accurate enough This was not tested on this occasion 27 Environmental Parameter Comment Light Again three models are available but only two are likely to be used in environmental monitoring The 3122 is an all purpose light sensor 0 to 100 000 lux suitable for outdoor use e g in sunlight A smoothed response is designed to filter out high frequency signals The response rate was satisfactory The 3120 0 to 1 000 lux has a photodiode sensitive to light in the 350 nm to 700 nm range i e a response similar to that of the human eye The slow linear response is suitable for studying plant growth indoors for example Oxygen This sensor also requires both the adapter and the oxygen electrode 3131 The oxygen electrode is suitable for use in air 0 to 25 in air and in saturated solutions 0 to 125 in saturated solution in water Testing of oxygen content in air gave readings within the expected range but no tests were done to ascertain dissolved oxygen pH pH measurement requires both the adapter a
119. ut 4 to 5 hours in field use though this depends on which sensors are being used Pasco advises GLX should be stored with fully charged battery that typically has a three year life Wireless connection ML does not have wireless facility but GL does as an optional extra PASCO has a Bluetooth USB adapter enabling any computer with USB connections and at least Microsoft XP or Mac OS X to become Bluetooth enabled It also sells a PASPORT Airlink SI to permit any sensor to connect wirelessly to an enabled computer up to the usual limit of 10 m Stand The back of the GLX has a fold down prop Manual This comes with Quick start instruction cards that have concise instructions and clear illustrations and a Users guide and a DVD ROM The Users guide is very extensive and gives thorough instructions on using the Xplorer as a stand alone device or linked to a computer It also gives sample activities from across the curriculum The use of pictorial symbols makes the guidance easier to follow but time needs to be allocated to work through the guidance Languages Xplorer supports a range of languages Upgrades Firmware and software upgrades can be obtained on line by registering after purchase Weather proofing The Xplorer GLX is water resistant but not waterproof In the field users are advised to store in a waterproof carry case Field use The design enables hand grip use in the fie
120. xtensive guidance on this aspect is provided and the KCI storage solution is included Response rate and accuracy were Satisfactory Relative humidity The S1867 has a range of O to 100 and has built in temperature compensation It was not tested Sound The 81843 has a range of 30 to 110 dB resolution 1dB which covers all normal environments There is a choice of measurement in sound level dB or sound pressure KPa The response rate was quite good on comparing a quiet lab with overhead aircraft noise A more advance probe S1802 is also available enabling remote 1 or 2 point calibration to be carried out 55 Environmental Comment Parameter Stream flow The S1699 has a stream flow rate range of O to 5 m sec resolution of 0 05 m sec The impeller is supported on pole held by a handle across which the connecting cable runs The sensor was not tested Temperature The basic S1698 has a range of 20 C to 120 C resolution 0 2 C and can be used for temperature measurements of air or liquids The metal probe is resistant to corrosion in most mild laboratory chemical solutions Response time was satisfactory There is also a skin temperature sensor S1697 Ultraviolet The S1869 measures both UVA and UVB radiation within the range 0 to 100 W m resolution 1 Response to external investigation of the effect of clouds on UV radiation from the
121. yager SX includes logger DA61217 199 00 light and temperature sensor and single user software guide etc Timstar Voyager SX Air includes DA61219 249 00 Bluetooth enabled logger light and temperature sensor and single user software guide etc Voyager comes in both Windows and Mac versions 34 Supplier Catalogue number Price Beecroft Explorer starter pack WDA 00101 serial port 263 26 WDA 00102 USB port 253 13 Blackboard Associates Explorer including temperature LoglT Explorer serial or USB 180 00 probes port Commotion Explorer starter set 12452 USB port 179 00 GLS Explorer G48373270 200 90 Griffin Education Explorer starter pack CRD 600 030N 179 99 NES Arnold Explorer 04BJ72620 229 95 Rapid Explorer 85 2660 serial port 163 00 85 2661 USB port 173 00 RM Explorer 1CZ 900 USB port 179 99 1CZ 901 Serial port 169 99 TAG Learning Explorer including Explorer 169 00 2 temperature probes Timstar Explorer includes logger DA61238 serial port 179 99 hee eee Also available at same price with t USB port TTS Explorer 849 LoglT 165 00 YPO Explorer D90350 serial port 165 00 D90351 USB 175 00 Explorer comes in both Windows and Mac versions 35 8 3 3 DCP loglT Black Box Interface LogIT Weight 76g BLACK BOX DATALOGGER Width 66 mm Height 66 mm Depth 30

R142 Equipment and Materials for Environmental Monitoring. (03/09)

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