FIELD AND LABORATORY WORK a. Fieldwork items

3.6.1.a. Fieldwork Items Fred Kruis (Head UNESCO-IHE lab) Peter Kelderman UNESCO-IHE Institute for Water Education Online Module Water Quality Assessment 2

Sampling Aim of sampling: To collect samples (usually extremely small fractions) of the water in such a way that the quality of the sample represents the quality of the original water body. 3 To achieve that aim, the sample must be: Representative Valid

Sampling (cont’d) Representative sample Sample must be collected and handled so that the values of the determinants represent the values of the original water body. 4 Valid sample A representative sample is valid if it provides a true representation of the variations ( time, depth and/or flow ) of the quality of the water body for the duration of the sampling programme.

Representative Sample Volume: Is determined by the analytical methods. Fill sample container completely: When contact with air must be avoided, e.g. determination of dissolved gases, to prevent oxidation, determination of pH and conductivity in weakly buffered waters 5

Representative Sample (cont’d) Fill sample container not completely: When sample requires vigorous shaking before taking portions for analysis, e.g. for the determination of suspended solids or bacteria. Collect the total volume of sample in several containers and use preservation agents in order to ensure adequate stability of the determinants between sampling and analysis. Consult the international standard ISO (see later). 6

Representative Sample (cont’d) Collection of a sample - Measure on-site: pH, EC (electrical conductivity), DO (dissolved oxygen) and Temperature, with probes - Allow the water to run through the sample container for some time - Prevent contamination of bottle caps or stoppers while the bottles are being filled. 7

Valid sample 8 Position of the sample location Determine if there is: - complete mixing, important for river sites - stratification, for ponds and lakes - plug flow, e.g. for waste water discharges

Locations for sampling “Easy” locations: -Influent or effluent of a wastewater treatment plant -Point of intake for drinking water production. “Difficult” locations: -In case you want to know the effect of the discharge of waste water on the quality of a river/lake. A careful selection of the sampling locations is required. 9

Storage of samples Chemical, biological and physical reactions may occur during storage: - bacteria, algae and other species may consume, excrete or change the chemical form of e.g. pH, DO, BOD, CO 2, NO 3, NH 4, PO 4, alkalinity, hardness, etc. - oxidation can occur, e.g. for Fe 2+ - precipitation of e.g. CaCO 3 and metals - CO 2 absorption from air can change pH, EC, alkalinity 10 - components can adsorb to the wall of the container, e.g. benzene to plastic or trace metals to glass - components can leach from the wall of the container, e.g. sodium and silica can leach from glass, organics from plastic.

Sample containers / material Wrong use of plastic funnel for sampling organic micropollutants  contamination! 11

Sample containers, methods of preservation and maximum storage time (see later) Follow International Standard ISO For each determinant is described: - material of the container: P, G, BG. - method of preservation: e.g. cooling, acidification, dark/light storage - maximum time between sampling and analysis 12

13 FIELDWORK AND SAMPLING CHECKLIST Careful planning Well trained staff

14 Filtration, if needed; after that collecting in clean bottles Labelling the samples Always note down time of sampling Correct preservation methods See next slide for modified table!

15 Determinant Material of sample container Method of preservation Maximum time between sampling and analysis Ca, Mg, Na, K,..P, acid-washedHNO 3, pH 1-21 month Anions (Br, F, Cl, NO 2, NO 3, PO 4, SO 4 ) P or GCool to 1-5ºC or freeze -20ºC 24 h. respectively 1 month. Filter on-site SulfateP or GCool to 1- 5ºC1 month Alkalinity, HCO 3 P or GCool to 1- 5ºC24 hours BODP or GCool to 1- 5ºC or freeze to -20ºC 24 h. resp. 1 month. in the dark, exclude air CODP or GCool to 1- 5ºC or freeze to -20ºC24 h. resp. 6 month. in the dark Nitrogen, ammoniaP or GH 2 SO 4, pH 1-2 and cooling 1-5ºC21 days. Filter on-site Nitrogen, nitrateP or G HCl, pH 1-2 or cool to 1-5ºC or freeze –20ºC 7 days resp. 24 h resp. 1 month Phosphorus, total P/G/BG acid- washed H 2 SO 4, pH 1-2 or freeze -20ºC6 months Phosphorus, dissolved P/G/BG acid- washed Cool to 1- 5ºC or freeze to -20ºC1 month. Filter on-site Heavy metals, except for mercury P/BG acid-washedHNO 3, pH 1-26 months MercuryBG acid-washedHNO 3, pH 1-2, add K 2 Cr 2 O 7 until final conc of 0.05% 1 month Glassware/preservation, according to ISO P= polyethylene; G=glass; BG = borosilicate glass

pH, DO, EC, T measurements 16

17 HYDROLOGICAL VARIABLES Velocity (m/s); discharge (m 3 /s): should always be included in river monitoring programmes Velocity: use current meter, or ”floating object” (orange). Sophisticated: Doppler instrument (Acoustic Doppler Current Profiler; ADCP)

18 TECHNIQUES Measure velocity river at various depths  average Divide river width into stretches, each with own water depth and velocity  discharge (m 3 /s)

LAKE MONITORING 19

Nansen water sampler for taking samples at different depths. Flaps are closed by releasing the weight on the wire 20

Field measurements Secchi disc transparency 21

22 FIELD NOTEBOOK Data on site, date/time, weather conditions,.. Sampling data; preservation, transport,.. Analyses on site Persons involved  later checking possible !

23 Water Laboratory Nusantara, Manado, Indonesia Clockwise, starting Electrodes for pH, EC,.. AAS for heavy metals Colorimeter for phosphate, ammonia, nitrate, etc.

24 Fieldkit for phosphate, ammonia, nitrate,..

“Ready to use “ reagents for nutrient analysis 25

26 See PowerPoint b. on sampling, by the Netherlands “Centre of Water Management” (part of Ministry of Infracture and the Environment )