PHYSCO-CHEMICAL WATER QUALITY PHYSCO-CHEMICAL WATER QUALITY MONITORING OF THE OKAVANGO MONITORING OF THE OKAVANGO

DELTA: A PRACTICAL GUIDE TO FIELD DELTA: A PRACTICAL GUIDE TO FIELD MEASUREMENTS AND WATER MEASUREMENTS AND WATER

SAMPLINGSAMPLING

W. R.L. MasambaW. R.L. MasambaHarry Oppenheimer Okavango research Centre, Harry Oppenheimer Okavango research Centre,

University of Botswana, P/Bag 285, Maun, BotswanaUniversity of Botswana, P/Bag 285, Maun, Botswana

Workshop on Field Measurements and Water sampling, Camp Moremi and Workshop on Field Measurements and Water sampling, Camp Moremi and Khwai River lodge, 10-11 March 2009Khwai River lodge, 10-11 March 2009

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SUMMARYSUMMARY

WATER SAMPLINGWATER SAMPLING BASIS OF INSTRUMENTAL METHODSBASIS OF INSTRUMENTAL METHODS TURBIDITYTURBIDITY PHPH DISSOLVED OXYGENDISSOLVED OXYGEN ELECTRICAL CONDUCTIVITYELECTRICAL CONDUCTIVITY

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WATER SAMPLINGWATER SAMPLING

The results of any testing method are no The results of any testing method are no better that the sample on which it is better that the sample on which it is performed performed

OBJECTIVE OF SAMPLING: collect a OBJECTIVE OF SAMPLING: collect a portion of material small enough to be portion of material small enough to be transported conveniently and yet large transported conveniently and yet large enough to be analysedenough to be analysed

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WATER SAMPLINGWATER SAMPLING

The methods of water sampling include:The methods of water sampling include: Collection of a sample by hand,Collection of a sample by hand, Collection by grab automatic sampler,Collection by grab automatic sampler, Samplers that collect and integrate samples Samplers that collect and integrate samples

over a given time over a given time

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WATER SAMPLINGWATER SAMPLINGFor our purposes For our purposes The samples will be collected on the day that they The samples will be collected on the day that they

will be sent to the Harry Oppenheimer Okavango will be sent to the Harry Oppenheimer Okavango Research Centre (HOORC) laboratory Research Centre (HOORC) laboratory

The samples will be collected between 9 and 11 The samples will be collected between 9 and 11 amam

The samples will be sampled by hand The samples will be sampled by hand Sampling will be done at 25cm below the water Sampling will be done at 25cm below the water

surfacesurface The sampler or vessel being used will be The sampler or vessel being used will be

downstream of the sampling point to avoid downstream of the sampling point to avoid contamination.contamination.

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WATER SAMPLINGWATER SAMPLING When 1L sample containers are used, three samples will When 1L sample containers are used, three samples will

be collected. be collected. When 250-300 ml sample containers are used, six When 250-300 ml sample containers are used, six

samples will be collected samples will be collected The only preservation of the samples will be to put them The only preservation of the samples will be to put them

in cooler boxes with cold bricks where available and then in cooler boxes with cold bricks where available and then sent to HOORC sent to HOORC

SAFETYSAFETY– The sampling method assumes that the water sample is safe The sampling method assumes that the water sample is safe

to be handled. If not, gloves should be wornto be handled. If not, gloves should be worn LABELLINGLABELLING

– Sample site e.g. Guma, Mohembo, Shakawe etcSample site e.g. Guma, Mohembo, Shakawe etc– Date samples. For consistency, the day followed by month Date samples. For consistency, the day followed by month

and then year (e.g. 5/8/2008) should be used.and then year (e.g. 5/8/2008) should be used.– Initials of the person sampling should be indicated. Initials of the person sampling should be indicated. – The bottles should also be labeled “not Filtered”.The bottles should also be labeled “not Filtered”.

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BASIS OF INSTRUMENTAL BASIS OF INSTRUMENTAL METHODSMETHODS

Instrument should respond to substance Instrument should respond to substance analysed analysed

There should be a relationship between There should be a relationship between instrument response and concentration instrument response and concentration (Figure 1)(Figure 1)

The response-concentration characteristics The response-concentration characteristics in Figure 2 are not acceptablein Figure 2 are not acceptable

There should be standards for calibrationThere should be standards for calibration

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BASIS OF INSTRUMENTAL BASIS OF INSTRUMENTAL METHODSMETHODS

Examples of acceptable responsesExamples of acceptable responses

Figure 1. Acceptable response characteristics of instruments

Concentration

InstrumentResponse

A

B

C

D

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BASIS OF INSTRUMENTAL BASIS OF INSTRUMENTAL METHODSMETHODS

Examples of unacceptable responsesExamples of unacceptable responses

CONCENTRATION

INSTRUMENTRESPONSE

Figure2. Unsuitable responses

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TURBIDITYTURBIDITY

Turbidity is the property of the optical Turbidity is the property of the optical property of the water that causes light to be property of the water that causes light to be scattered and absorbed rather than scattered and absorbed rather than transmitted in straight lines though the transmitted in straight lines though the sample sample

Caused suspended and colloidal matter Caused suspended and colloidal matter such as clay, silts, finely divided organic and such as clay, silts, finely divided organic and inorganic matter, plankton and other inorganic matter, plankton and other microscopic microorganisms. microscopic microorganisms.

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TURBIDITYTURBIDITY

InstrumentationInstrumentation

Detector at 90º

Scattered light

Transmitted light

90º

LampLens Glass sample

vial

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TURBIDITYTURBIDITYCALIBRATIONCALIBRATION

The standards provided should be used. The standards provided should be used. They should not be violently shaken or agitated They should not be violently shaken or agitated They should not be stored in freezing temperatures They should not be stored in freezing temperatures They should not be openedThey should not be opened Always hold them by the caps Always hold them by the caps Calibration should be done each time samples are collectedCalibration should be done each time samples are collected

Ensure that batteries are installed.Ensure that batteries are installed. Place the instrument on a flat and level surface (not in the hand)Place the instrument on a flat and level surface (not in the hand) Insert the CAL 1 standard (800 NTU) into the sample well, aligning Insert the CAL 1 standard (800 NTU) into the sample well, aligning

the sample on the vial with the mark on the meterthe sample on the vial with the mark on the meter Press down until it snaps fully into the instrumentPress down until it snaps fully into the instrument Cover the vial with the light shield capCover the vial with the light shield cap Press the ON/OFF key to switch on the meterPress the ON/OFF key to switch on the meter Select the calibration function of the instrument by pressing the CAL Select the calibration function of the instrument by pressing the CAL

key oncekey once “ “CAL” blinks momentarily and the meter prompts for the first STDCAL” blinks momentarily and the meter prompts for the first STD

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TURBIDITYTURBIDITY

Press the READ/ENTER keyPress the READ/ENTER key ““CAL” blinks for about 12 seconds while the CAL” blinks for about 12 seconds while the

instrument performs the calibration of the first instrument performs the calibration of the first point.point.

The instrument then prompts for the next The instrument then prompts for the next standard, “CAL 2 100 NTU”.standard, “CAL 2 100 NTU”.

Repeat for CAL 2, CAL 3 and CAL 4.Repeat for CAL 2, CAL 3 and CAL 4. After calibration with CAL 2, the instrument After calibration with CAL 2, the instrument

shown “STbY”.shown “STbY”. The meter is now ready for measurements.The meter is now ready for measurements.

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TURBIDITYTURBIDITY

RESTORING FACTORY CALIBRATIONRESTORING FACTORY CALIBRATION With the meter switched off press▲ keyWith the meter switched off press▲ key Switch the meter on using the ON/OFF button. Switch the meter on using the ON/OFF button. Release the ▲key when the “URST” appears on the Release the ▲key when the “URST” appears on the

displaydisplay The display shows URST for 3 seconds and then shows The display shows URST for 3 seconds and then shows

NONO Use ▲or ▼ to select between yes or no:Use ▲or ▼ to select between yes or no: YES-restore to factory valuesYES-restore to factory values No-retain current valuesNo-retain current values Press READ/ENTER key to confirm your selection.Press READ/ENTER key to confirm your selection. The display flashed –Rd- about 10 times indicating that the The display flashed –Rd- about 10 times indicating that the

meter is going to the READ mode.meter is going to the READ mode.

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TURBIDITYTURBIDITY TURBIDITY MEASUREMENTSTURBIDITY MEASUREMENTSThe units for turbidity are NTU (Nephelometric Turbidity Units). The units for turbidity are NTU (Nephelometric Turbidity Units).

A sample vial must be in the sample well before measurements A sample vial must be in the sample well before measurements can be donecan be done

The light shield should be used during measurementsThe light shield should be used during measurements Preparation of sample vialPreparation of sample vial A clean sample vial should be usedA clean sample vial should be used Handle the vial by the top onlyHandle the vial by the top only Rinse the vial with approximately 10 ml of sample, several Rinse the vial with approximately 10 ml of sample, several

times, discard the sample and repeat two more timestimes, discard the sample and repeat two more times Fill the vial to the mark with sampleFill the vial to the mark with sample Cap the vial with the black screw capCap the vial with the black screw cap Wipe vial with the soft lint free cloth suppliedWipe vial with the soft lint free cloth supplied Apply a thin layer of silicone oil supplied on sample vialApply a thin layer of silicone oil supplied on sample vial Wipe with a soft cloth to obtain an even distribution over the Wipe with a soft cloth to obtain an even distribution over the

surface of the vialsurface of the vial Insert vial into the instrument and align markInsert vial into the instrument and align mark

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TURBIDITYTURBIDITY Push the vial until it snaps into placePush the vial until it snaps into place Cover the vial with the light shieldCover the vial with the light shield Turn on the meterTurn on the meter The measured value appears on display after power set up The measured value appears on display after power set up

sequencesequence Repeat for all samples, pressing the READ/ENTER keyRepeat for all samples, pressing the READ/ENTER key Samples above range should be indicated as >1000 NTUSamples above range should be indicated as >1000 NTU

NBNB Never pour samples while the vial is in the instrument-spills will Never pour samples while the vial is in the instrument-spills will

damage the instrumentdamage the instrument Never attempt to clean the sample wellNever attempt to clean the sample well The instrument automatically switches off 20 minutes after the The instrument automatically switches off 20 minutes after the

last key was pressedlast key was pressed Only the single shot method will be usedOnly the single shot method will be used Be familiar with the troubleshooting (P.15).Be familiar with the troubleshooting (P.15).

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TURBIDITYTURBIDITY

MAINTENANCEMAINTENANCE Use the supply case to protect the meterUse the supply case to protect the meter Use vials that are clean and free from scratches, Use vials that are clean and free from scratches,

marks and smudgesmarks and smudges Avoid contamination of samp,esAvoid contamination of samp,es Wash vial with dish washing detergent when Wash vial with dish washing detergent when

necessary, final rise should be with distilled waternecessary, final rise should be with distilled water Samples and calibration standards should always Samples and calibration standards should always

be handled by the capbe handled by the cap

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PHPH pH is a measure of the acid (or base) concentration. pH is a measure of the acid (or base) concentration. Even moderately acidic waters (low pH) may reduce the hatching Even moderately acidic waters (low pH) may reduce the hatching

success of fish eggs, irritate fish and aquatic insect gills and damage success of fish eggs, irritate fish and aquatic insect gills and damage membranes.membranes.

Water with extremely high or low pH is deadly. A pH below 4 or above Water with extremely high or low pH is deadly. A pH below 4 or above 10 will kill most fish and very few animals can tolerate waters with a pH 10 will kill most fish and very few animals can tolerate waters with a pH below 3 or above 11.below 3 or above 11.

Amphibians are particularly vulnerable to low pH, probably because Amphibians are particularly vulnerable to low pH, probably because their skin is so sensitive to pollutants. their skin is so sensitive to pollutants.

A change in the pH of water can alter the behavior of other chemicals A change in the pH of water can alter the behavior of other chemicals in the water. The altered water chemistry may affect aquatic plants and in the water. The altered water chemistry may affect aquatic plants and animals. For example, ammonia is relatively harmless to fish in water animals. For example, ammonia is relatively harmless to fish in water that is neutral or acidic. But, as the water becomes more basic (the pH that is neutral or acidic. But, as the water becomes more basic (the pH increases) ammonia becomes increasingly toxic.increases) ammonia becomes increasingly toxic.

Heavy metals such as cadmium, lead and chromium dissolve more Heavy metals such as cadmium, lead and chromium dissolve more easily in more acidic water (lower pH). This is important because many easily in more acidic water (lower pH). This is important because many heavy metals also become much more toxic when dissolved in water.heavy metals also become much more toxic when dissolved in water.

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PHPH Certain dissolved minerals, such as calcium carbonatecan cause the Certain dissolved minerals, such as calcium carbonatecan cause the

water to be basis.water to be basis. Trees in the watershed may lower pH of the water. The decomposing Trees in the watershed may lower pH of the water. The decomposing

plant material e.g. leaves of these trees add to the acidity of soils and plant material e.g. leaves of these trees add to the acidity of soils and also influence the acidity of nearby streams.also influence the acidity of nearby streams.

““acid rain,” increases the acidity of surface water near many industrial acid rain,” increases the acidity of surface water near many industrial or large urban areas. The main contributors to acid rain are sulfuric or large urban areas. The main contributors to acid rain are sulfuric acid (produced by coal burning industries) and nitric acid (produced by acid (produced by coal burning industries) and nitric acid (produced by automobile engines). automobile engines).

Dumping industrial pollutants directly into waters – also known as point Dumping industrial pollutants directly into waters – also known as point source pollution – can have intense and immediate effects on the pH of source pollution – can have intense and immediate effects on the pH of a stream.a stream.

Mining may expose rocks to rain water and produce acidic runoff. Mining may expose rocks to rain water and produce acidic runoff. Mining drainage can therefore introduce acids into streamsMining drainage can therefore introduce acids into streams

When aquatic plants convert sunlight to energy during photosynthesis, When aquatic plants convert sunlight to energy during photosynthesis, they remove carbon dioxide from the water. This can raise the pH of they remove carbon dioxide from the water. This can raise the pH of your stream. Since photosynthesis occurs only when light is present, your stream. Since photosynthesis occurs only when light is present, the highest pH in your water body often occurs in the late afternoon. the highest pH in your water body often occurs in the late afternoon. Likewise, lowest pH levels will occur just before sunrise.Likewise, lowest pH levels will occur just before sunrise.

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PHPH

PH MEASUREMENTSPH MEASUREMENTS The measurements are based on a pH The measurements are based on a pH

electrode is responds to the concentration of electrode is responds to the concentration of hydronium ions. The electrode has a glass hydronium ions. The electrode has a glass tip that responds to the pH.tip that responds to the pH.

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Legend 1. a sensing part of electrode, a bulb made from specific

glass 2. sometimes electrode contain small amount of AgCl

precipitate inside the glass electrode 3. internal solution, usually 0.1M HCl for pH electrodes 4. internal electrode, usually silver chloride electrode or

calomel electrode 5. body of electrode, made from non-conductive glass or

plastics. 6. reference electrode, usually the same type as 4 7. junction with studied solution, usually made from

ceramics or capillary with asbestos or quartz fiber.

PHPHElectrodeElectrode

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pHpH pH METERpH METER Install batteriesInstall batteries Connect probe by aligning the pins with the holes in the port (arrow up)Connect probe by aligning the pins with the holes in the port (arrow up) The temperature sensing probe is included in the electrodeThe temperature sensing probe is included in the electrode The meter is turned on by the on/off/exit keyThe meter is turned on by the on/off/exit key The meter will display the temperature (range -10 to 100ºC)The meter will display the temperature (range -10 to 100ºC) We will not use the mV settingWe will not use the mV setting The meter will shut off 15 min after the last key was depressedThe meter will shut off 15 min after the last key was depressed Chosinf the probe connectorChosinf the probe connector

– Switch on the instrumentSwitch on the instrument– From the reading mode press setupFrom the reading mode press setup– The setup icon and the number 1 (flashing) will be displayedThe setup icon and the number 1 (flashing) will be displayed– Pressing enter toggles between BNC and 5 pinPressing enter toggles between BNC and 5 pin– When the desired option is selected, press exit to return to reading When the desired option is selected, press exit to return to reading

menumenu

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pHpH Turning display lock on and offTurning display lock on and off

– Setup 2 is the display lock option. This stops Setup 2 is the display lock option. This stops measurement readings from fluctuating on the display measurement readings from fluctuating on the display once a stable reading is reached.once a stable reading is reached.

– From the reading menu press setupFrom the reading menu press setup– The setup icon and 1 will flashThe setup icon and 1 will flash– Press up arrow once so that the setup number is 2Press up arrow once so that the setup number is 2– Change the display lock status by pressing enter. This Change the display lock status by pressing enter. This

toggles the display between off and on.toggles the display between off and on.– Press exit when desired option is selectedPress exit when desired option is selected

Setting Temperature unitsSetting Temperature units– From the reading menu press setupFrom the reading menu press setup– Setup icon wit 1 flashing will be displayedSetup icon wit 1 flashing will be displayed– Press up arrow until setup number 3 is displayedPress up arrow until setup number 3 is displayed

Change the temperature units by pressing enter Change the temperature units by pressing enter (toggles between ºC and ºF). (toggles between ºC and ºF).

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pHpH Selecting measurement resolutionSelecting measurement resolution

– The meter can display to a tenth (0.0) a hundredth The meter can display to a tenth (0.0) a hundredth (0.00) and a thousandth (0,000) of a pH unit(0.00) and a thousandth (0,000) of a pH unit

– From setup mode press setupFrom setup mode press setup– Press up arrow to setup number 4Press up arrow to setup number 4– Change the resolution by pressing enterChange the resolution by pressing enter– Press exit when desired option is enteredPress exit when desired option is entered

Selecting auto buffer recognitionSelecting auto buffer recognition– The meter can recognize the buffer and calibrate on pH The meter can recognize the buffer and calibrate on pH

4.01, 6.86, 7.00 and 10.014.01, 6.86, 7.00 and 10.01– The only selection option is pH 6.86 or 7.00The only selection option is pH 6.86 or 7.00

The default is 7.00The default is 7.00 From reading mode press setupFrom reading mode press setup Press up arrow until setup number 5 is displayedPress up arrow until setup number 5 is displayed Change the buffer value by pressing enter. This toggles Change the buffer value by pressing enter. This toggles

between 6.86 and 7.00between 6.86 and 7.00 When the desired option is selected press exitWhen the desired option is selected press exit

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pHpH CALIBRATING THE METERCALIBRATING THE METER

Two or three point calibration is recommendedTwo or three point calibration is recommended We will be using a two point calibration for now-pH 4.01 and We will be using a two point calibration for now-pH 4.01 and

7.007.00 Turn the instrument onTurn the instrument on Put electrode in bufferPut electrode in buffer From the reading mode press CAL. CAL and flashing ? will From the reading mode press CAL. CAL and flashing ? will

appear in the upper display area, along with standard and 1appear in the upper display area, along with standard and 1 Press READ/ENTER to calibratePress READ/ENTER to calibrate When a stable the standard number will change to 2When a stable the standard number will change to 2 Remove the probe from the first buffer and rinse with deionised Remove the probe from the first buffer and rinse with deionised

water. Place in second bufferwater. Place in second buffer Press exit when second buffer has calibrated Press exit when second buffer has calibrated Press READ/ENTER . The temperature and pH value will be Press READ/ENTER . The temperature and pH value will be

updatedupdated When reading has stabilized or been accepted, the slope and When reading has stabilized or been accepted, the slope and

the store and ? icon will appear. Verify the slope is within the the store and ? icon will appear. Verify the slope is within the ranges specified in the electrode manual (-58±3) otherwise ranges specified in the electrode manual (-58±3) otherwise repeat calibrationrepeat calibration

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pHpH

MEASURING SAMPLESMEASURING SAMPLES Rinse electrode and place it in sampleRinse electrode and place it in sample Press READ/ENTERPress READ/ENTER When the reading is stable stabilizing… will When the reading is stable stabilizing… will

disappear. If the display lock is enabled, the disappear. If the display lock is enabled, the display will lock in.display will lock in.

Record the pH valueRecord the pH value Remove the electrode from the sample, rinse with Remove the electrode from the sample, rinse with

deionised waters and place the electrode in the deionised waters and place the electrode in the next sample and repeat for all samplesnext sample and repeat for all samples

Turn off meterTurn off meter

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pHpH ASSEMBLING ELECTRODEASSEMBLING ELECTRODE Remove electrode from the soaker bottle providedRemove electrode from the soaker bottle provided Remove the cap from the electrolyte cartridgeRemove the cap from the electrolyte cartridge Align the fins on the cartridge with grooves on the electrodeAlign the fins on the cartridge with grooves on the electrode Press the cartridge firmly into the inlet tube of the electrode Press the cartridge firmly into the inlet tube of the electrode

and rotate the electrode clockwise until it is seatedand rotate the electrode clockwise until it is seated Place the dispenser unit over the electrolyte cartridgePlace the dispenser unit over the electrolyte cartridge Screw the dispenser into the electrode body until it stops Screw the dispenser into the electrode body until it stops

turningturning If the electrolyte gel is not visible at the reference outlet, If the electrolyte gel is not visible at the reference outlet,

depress the pump button until it clicks; release the button. depress the pump button until it clicks; release the button. Repeat until gel is visible at the reference outlet.Repeat until gel is visible at the reference outlet.

Rinse electrode with deionized water and blot dry. Do not Rinse electrode with deionized water and blot dry. Do not scrub bulbscrub bulb

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pHpH

CONDITIONING THE ELECTRODECONDITIONING THE ELECTRODE Electrode should be placed in a solution Electrode should be placed in a solution

comparable to the sample in terms of pH comparable to the sample in terms of pH and ionic strength for 10-15 minutesand ionic strength for 10-15 minutes

In between uses, store the electrode in tap In between uses, store the electrode in tap water. water.

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DISSOLVED OXYGENDISSOLVED OXYGEN

measures the amount of gaseous oxygen (O2) dissolved in measures the amount of gaseous oxygen (O2) dissolved in an aqueous solution. an aqueous solution.

Oxygen gets into water by diffusion from the surrounding Oxygen gets into water by diffusion from the surrounding air, by aeration (rapid movement), and as a waste product air, by aeration (rapid movement), and as a waste product of photosynthesis. of photosynthesis.

Oxygen is removed from the water by the respiration of Oxygen is removed from the water by the respiration of fish, other aquatic life and plants; and also by bacteria that fish, other aquatic life and plants; and also by bacteria that decompose organic matter. Organic materials may be decompose organic matter. Organic materials may be man-made, such as sewage, or natural, such as leaf litter. man-made, such as sewage, or natural, such as leaf litter.

As dissolved oxygen levels in water drop below a certain As dissolved oxygen levels in water drop below a certain level, aquatic life can be put at risk, and low levels over a level, aquatic life can be put at risk, and low levels over a period of time can, in fact, result in large fish kills. period of time can, in fact, result in large fish kills.

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DISSOLVED OXYGENDISSOLVED OXYGEN

ELECTRODE

ELECTRODE

Oxygen diffuses through the Teflon “plastic” membrane into the electrode and is measured.

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DISSOLVED OXYGENDISSOLVED OXYGEN

CALIBRATIONCALIBRATION Place 5-6 drops of water into the sponge in the calibration Place 5-6 drops of water into the sponge in the calibration

bottlebottle Turn the bottle over and allow excess water to drainTurn the bottle over and allow excess water to drain The wet sponge creates a 100% water saturated air The wet sponge creates a 100% water saturated air

environment for the probe, which is used for calibrationenvironment for the probe, which is used for calibration Slide probe into the bottle, the membrane should not touch Slide probe into the bottle, the membrane should not touch

the spongethe sponge Turn the meter onTurn the meter on Press CALPress CAL The LCD prompts for the local pressure in mBarThe LCD prompts for the local pressure in mBar

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DISSOLVED OXYGENDISSOLVED OXYGEN

We will use the altitude of 1000 m: pressure = 900 We will use the altitude of 1000 m: pressure = 900 mBarmBar

When the proper display displays press enter once When the proper display displays press enter once to view the calibration value. to view the calibration value.

When the value stabilizes, press enter again to When the value stabilizes, press enter again to move to salinity compensation modemove to salinity compensation mode

The display prompts for the approximate salinity of The display prompts for the approximate salinity of the water to be analysed.the water to be analysed.

Use ▲ or ▼ to set the salinity at 0 and press enterUse ▲ or ▼ to set the salinity at 0 and press enter

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DISSOLVED OXYGENDISSOLVED OXYGEN

y = -0.1017x + 1004.4

600

650

700

750

800

850

900

950

1000

1050

0 500 1000 1500 2000 2500 3000 3500

Altitude (m)

Pre

ssu

re (

mB

ar)

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DISSOLVED OXYGENDISSOLVED OXYGEN

PROBE MAINTENANCEPROBE MAINTENANCE Any problems should be referred to the Any problems should be referred to the

HOORC labHOORC lab Avoid damage of the plastic membrane Avoid damage of the plastic membrane

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ELECTRICAL CONDUCTIVITYELECTRICAL CONDUCTIVITY Electrical conductivity is a measure of the ability of an Electrical conductivity is a measure of the ability of an

aqueous solution to carry an electric current, and is a aqueous solution to carry an electric current, and is a measure of ionic solutes in the watermeasure of ionic solutes in the water

CALIBRATIONCALIBRATION Pour the 1423 µS/cm standard into a small plastic Pour the 1423 µS/cm standard into a small plastic

container to 8cmcontainer to 8cm Make sure that the probe is connected to the meterMake sure that the probe is connected to the meter Rinse the probe in deionised water and blot dryRinse the probe in deionised water and blot dry Immerse the probe in the standard. The level of the Immerse the probe in the standard. The level of the

solution must be higher than the holes on the PVC sleevesolution must be higher than the holes on the PVC sleeve Turn the instrument onTurn the instrument on Tap the probe repeatedly and stir to make sure that no air Tap the probe repeatedly and stir to make sure that no air

bubbles are trapped inside the sleevebubbles are trapped inside the sleeve When the meter stabilizes, turn the calibration trimmer to When the meter stabilizes, turn the calibration trimmer to

read 1423 µS/cmread 1423 µS/cm Rinse the probeRinse the probe Rinse the probe after each determinationRinse the probe after each determination

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SAMPLING SITESSAMPLING SITES

WATER QUALITY PARAMETES TO BE WATER QUALITY PARAMETES TO BE MEASURED/SAMPLING FREQUENCYMEASURED/SAMPLING FREQUENCY

Field parameters to be measuredElectrical conductivity, pH, dissolved oxygen, temperature and turbidity carbonate and bicarbonate.

Laboratory parameters to be measuredBOD, dissolved organic carbon, suspended solids, Total nitrogen, total and dissolved phosphorus, nitrate, chloride, sulphate, phosphate, carbonate, bicarbonate, ammonia, silica, turbidity, and chlorophyll a, sodium, potassium, calcium, magnesium, aluminium, lead, cadmium, copper, nickel and manganese

Sampling frequencyEvery two weeks from the centre of the channel or lagoon.

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FOLLOW UPFOLLOW UP

– Meetings will be arranged to discuss results and address any problems that may have been identified.

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THANK YOUTHANK YOU