Water chemistry sampling
By: K. Gajewski
This procedure should be followed to collect and process water samples
for nutrient and trace element analysis. Note that the actual water chemistry
is done in the lab using the various instruments (ICP, etc.). This procedure
was shown to me by Paul Hamilton of the Canadian Museum of Nature.
A) Preparation before leaving for the field
Before sending the equipment to the field site the following washing
procedure must be used:
1. Wash and scrub filtration units with non-phosphate detergent.
2. Rinse with tap water and soak overnight in 5 – 10% HCl.
3. Clean tubing by soaking overnight in 5 – 10% HCl.
4. Rinse unit and tubing with tap water followed by distilled/deionized
Use the buckets of dilute acid in the corner of the pollen processing
lab. The next day, carefully take them out (use gloves, obviously, and
be careful that the solution does not go over the top of your gloves)
and wash them using a jet of tap water. Then, rinse them in deionized
water and place them to dry in the green clean-air hood. After the equipment
is dry, wrap it in aluminum foil and pack it to send. The sample bottles
should be prepared by acid washing as well, unless using City of Ottawa
bottles. Tape should be wrapped around them for the label, and they should
be labeled with the codes (e.g. K901, K902, ...) or that season. For each
lake you will need the following:
- 1 1-L plastic collection bottle
- 4 PEP bottles from the City of Ottawa (1 metals [white cap], 1 TP/TKN,
1 filtered TP/TKN/DOC, 1 Alkalinity/Anions/Cations [green caps])
Note that the chemicals (nitric and sulphuric acid etc.) cannot be shipped
by ordinary freight, so you need to make special arrangements to have
the bottles sent to the field station.
B) Field sampling
The information you collect depends a lot on the time available, the
space you have (ie. In the helicopter) to carry equipment, etc.
Minimum collection includes:
- pH, conductivity and temperature of the surface
- 1 L water sample
- 3 300-mL bottles filled
- Plankton tow
- Sediment sample
If possible the following should also be collected:
For more detailed work:
- Secchi depth
- Conductivity, temperature and oxygen profile
- Glew core(s)
- samples at several areas around the shore
- samples of water at several depths
At the lake, inflate the boat and get out to the central part. You should
first collect the water samples. Rinse bottles 3 times with lake water
before filling. Fill them below the water surface up to your elbow. Be
careful not to touch the spout, inside of caps, etc.
Chlorophyll a filtering procedure:
1. Rinse filtering apparatus in lake water.
2. Place GF/C glass microfibre filter on apparatus using tweezers.
3. Fill 1-L graduated cylinder with lake water from elbow depth (after
rinsing 3 times), pour into filtering apparatus and pump through. If lake
is productive use 500 mL or less depending on rate of flow.
4. Keep apparatus shaded while filtering.
5. Remove lid, fold filter in half using tweezers, wrap in foil, label
with lake name, date, and volume filtered. Freeze immediately by placing
between 2 ice packs.
Measure the pH, conductivity and temperature of the surface water. If
you can get a vertical profile of conductivity/temperature/oxygen, this
is certainly useful. A Secchi depth can be recorded, and 2-3 sediment
samples collected using a Glew corer or an Ekman Dredge. On the way back
to the shore, tow the plankton net behind you and put contents in a whirl
pack. They should be “fixed” with Lugol’s solution as
soon as possible.
C) Processing water
The procedure here doesn’t need to be followed in any particular
order, but individual steps should be closely followed.
1. For the following, use gloves and be very careful to avoid contamination.
The concentrations of the ions in lake water are very small, and touching
the sample containers can lead to serious contamination. Add 0.5 mL of
HNO3 (metals grade) to the metals bottle, and 0.5 mL of 30% H2SO4 to the
TP/TKN sample. Guideline is 2ml/1L of H2O and we are using 300 ml collection
2. For the filtered TP/TKN, use the cellulose acetate filter papers (47
mm diameter, pore size 0.45; order number CO45G047A). For this procedure,
you will be keeping the water that goes through the filter. Place the
filter on the filter holder,
ensuring it is centred, and close it tightly. Use the small (250 mL) filter
holder and a glass flask, and you will need the rubber stopper, or any
other part that may come in contact with the water. Put 10-20 mL of lake
water in the filter holder. Connect the vacuum pump, suck this water through,
swish it around the flask and discard. Filter between 250-300 mL of water
by pouring in increments into the filter holder. Maintain a vacuum of
7 or less. When the water has passed through, disconnect, toss the filter
paper and pour the filtrate into the appropriate 300 mL PEP bottle. Rinse
the unit with distilled H2O. Add 0.5 mL of 30% H2SO4 to the filtered TP/TKN
3. Place all the water samples in the cooler and keep refrigerated.
D) Shipping and storage
Samples should be shipped back to the lab as soon as possible. They should
be kept cool, but not frozen during this whole procedure.
E) Back in the lab
Back in the lab the samples should be processed as soon as possible.
The bottles are sent out for analysis to the City of Ottawa, Water Environment
This needs to be modified, depending on the number of sites and space
available. Here is the minimum amount we usually take; you can add extra
filter holders, flasks, etc., in case of breakage and also to run more
samples at a time if there are many analyses to do.
- 1-L collection bottles with caps, acid-washed (~10) (1 per lake)
- 300-mL PEP sample bottles; 3 with green caps for alkalinity, cations,
anions; TP/TKN; filtered TP/TKN; and 1 with white cap for metals
labels from City of Ottawa (4 per lake)
- Pkg Filters, 47 mm cellulose acetate, 0.45 um for filtered TP/TKN
- GF/C Whatman glass microfibre filter paper for chla (42.5 mm diameter,
0.45 um) (1 per lake)
- Vacuum pump (x2)
- Tubing for pump
- 500-mL plastic filter holder, with plastic reception vessel, caps
for all openings
- 250 mL plastic filter holder, with caps (x2)
- 500 mL ehrlenmeyer glass flasks (x2)
- rubber stoppers (x2)
- 100 mL glass graduated cylinder (x2)
- 1 L plastic graduated cylinder (x2)
- Plastic funnel
- pH meter (portable) (x2), pH test kit, batteries
- Conductivity meter with probe
- Oxygen meter with probe, YSI oxygen probe service kit
- Equipment manuals
- Plankton net
- Secchi disk
- Glew mini corer
- Glew extruder
- 10 mL pipettes (x 2-3)
- 1 mL pipette
- Acid dispensers (x2)
- Cooler(s), ice packs
- Plastic bottles to fill with water and freeze for ice to supplement
- Red/grey fishing tackle box with coring/filtering paraphanelia
- Including tweezers for filters, cleaning brush, exacto knife and scissors,
goop, T joints and clamps, one-way valve, markers and pencils, rubber
stoppers, clamps, black tape, manuals, forceps
- Aluminum foil, saran wrap, plastic for covering table and equipment,
whirl pack bags, large and small ziploc bags
- Concentrated nitric acid (metals grade) for preservation of metals
in water samples, 30% sulphuric acid (30 ml H2SO4 acid, 70 ml H2O) for
preservation of TP/TKN water samples (total and filtered)
- Lugols solution (5 g iodine, 10 g potassium oxide, 10 g glacial acetic
acid and 100 mL water [1 mL per 100 mL water sample]) for preservation
of zooplankton samples
- Turkey basters (x2)
- Non-phosphate detergent
- Plastic distilled water dispensers (squeeze bottles) (x2)
- 1 Box large nitrile gloves
- 1 Box large latex gloves
- Deionized water
- Pasteur pipettes and bulbs
- Safety goggles (x2)
- Lab coat
- Boat, life jackets, anchor (burlap bags), paddles
- Log books, log sheets for individual lakes
- Bear spray