PHYSICAL AND
CHEMICAL FIELD SAMPLING
EQUIPMENT LIST
clipboard, data sheet,
pencils, watch, duct tape
peristaltic
pump with attachment for filter holders
12
volt battery and cables to run pump
1/4"
I.D. tygon tubing to reach lake bottom,
1000 and 250 ml graduated cylinders
sample
bottles (one set per sampling depth plus
one extra set for blind)
pre-weighed
filters for total particulate matter
sediment
traps and lids, poison, retrieval hook
(Trout, Sparkling, and Crystal lakes)
temperature/oxygen
meter (YSI-58)
filters
(0.45µ Nuclepore polycarbonate) loaded in filter holders
cooler
(with icepack during summer)
(Primary
productivity gear: pipe, cooler, suck
tube, pipe-to-cooler tube, light screens)
BEFORE LEAVING TROUT LAKE STATION
Take
a barometric pressure reading, and record it in the lab notebook and on the
field data sheet.
Check
the checklist to be sure you have everything you will need in the field.
Attach
the cable leads to the front of the YSI temp/O2 meter. Leave the
probe in the moist plastic bag. Set the
function switch to ZERO and allow the meter to warm up for at least 15 minutes,
or until on station at lake.
SET UP (on station at the lake)
Record
the lake, station, date, observers, and time on the data sheet.
Calibrate
the YSI-58 oxygen meter.
-
The meter should be turned on to warm up for at least 15 minutes before
calibrating. Leave the probe in the
moist bag during calibration.
-
Turn the stirrer on.
-
Use the O2ZERO knob to set the display to 0.0.
-
Set the function switch to the TEMP position; record the probe temperature.
-
Determine the correct oxygen saturation value for the probe temperature and
barometric pressure using the table on the inside of the clipboard cover or the
calculation sheet on the iPAQ pda.
-
Set the function switch to the 0.01 mg/l position and use the O2CALIB
knob to set the display to the correct oxygen saturation value.
-
The probe may now be removed from the plastic bag. The YSI-58 may be moved without loss of
calibration.
Line
up the open end of the tubing with the sensors on the probe. Use duct tape to attach the tubing to the
oxygen probe, being careful to avoid covering the pressure compensating port
with tape or tubing.
TEMPERATURE AND OXYGEN MEASUREMENT
Determine
oxygen and temperature values at meter intervals down through the water column.
Record the time that you start and finish the
measurements. Be sure to allow enough
time at each depth for the meter to stabilize.
In general, the greater the change from the last value, the longer the
time needed for stabilization. To avoid
probe damage and mixing of sediments into the water column, do not lower the
probe into the sediments.
Read
the oxygen on the 0.01mg/l scale, but record the oxygen values to tenths.
WATER SAMPLE COLLECTION
Select the sample depths according to the temperature
profile. During stratification (late May
to late October), collect samples at the surface, the bottom of the epilimnion,
mid-thermocline, top of the hypolimnion, mid-hypolimnion, and one meter off the
bottom. During mixis and winter, collect
samples from the surface, mid water column, and one meter off the bottom. The depths selected should be depths at which
chlorophyll measurements will be made.
Record bottle numbers in the appropriate columns on the field data
sheet. Take a replicate
("blind") set of samples from one of the depths. The blind depth is selected randomly before
going out in the field.
Clear the sample tubing.
The tubing inlet should be at the bottom sample depth, one meter off the
bottom, after taking the temperature and O2 profile. Connect the tubing to the pump and run the
pump long enough to flush slightly more than one tubing volume from the
tubing. Each meter of 1/4" I.D.
tygon tubing holds a volume of approximately 32 ml. Therefore a 10 meter length of tubing, for
example, should have a least 320 ml pumped through it before filling any sample
bottles. The tubing must be cleared at every
depth before collecting samples at that depth.
Collect the water samples avoiding contamination of bottles
or filters. Rinse each bottle three
times with a small amount of the lake water it is to be filled with. Flush each filter by pumping a small amount
of lake water through it before collecting any filtered samples. Change filters at least every time you change
sampling depths. Do not touch inside or
rims of bottles, inside of bottle caps, or inlet/outlet holes on the filter
holders. Keep used filters out of the
clean filter container. Place bottles in
a cooler immediately after collection.
Keep samples cold and dark until analysis.
We sample for water chemistry at two levels of
intensity. Routine, approximately
monthly, sampling includes collection of samples for nitrate, nitrite, ammonia,
phosphorus, inorganic and organic carbon, silica, and pH. Four times a year we also collect samples for
major cations, major anions, conductivity, color, and alkalinity.
Routine Samples Quarterly Extra
Samples
Filtered Unfiltered Filtered Unfiltered
20ml 'N' 20ml pH 20ml 'V' 20ml alkalinity
125ml 'S' 125ml pH 125ml color 125ml cond.
15ml 'DIC DOC' 125 ml 'S'
TPM filters 15ml 'TIC TOC'
The 'N' vials are for nitrogen analysis and will be frozen
upon return to the lab. Fill only to
shoulder of bottle to keep them from breaking when frozen.
The 'V' vials are for sulfate and chloride and should be
filled completely.
The 'S' bottles for nutrient analysis should be filled to
the shoulder of the bottle and acidified with 1 ml concentrated OPTIMA HCl back
at the lab.
The water for pH, alkalinity, and carbon analyses should not
be agitated or exposed to air. This is
to avoid carbon dioxide loss or invasion.
Fill these bottles gently to the top plus some overflow, and carefully
screw on the displacement cap so that the sample contains no air bubbles. Invert the bottle and check for bubbles. Dump out and refill if there is a bubble in
the sample.
The filters for total particulate matter (TPM) have been
weighed before sample collection. Filter
lake water through these into a 250 ml graduated cylinder, stopping when the
filter is clogged or when you have pumped 250 ml. Record the filter holder number and the
volume filtered on the field data sheet.
At the lab remove the filters from the holders and return them to the
numbered plastic cases; freeze.
Record the time you start and finish collection of chemistry
samples.
In Trout, Sparkling, and Crystal Lakes two sediment traps must be retrieved and replaced each
chemistry sampling week. Details of the
sediment trap procedure are in the Sediment Trap / TPM protocol document.
CLEAN-UP
FIELD: Turn meters
off. Record an 'off station' time.
LAB: Preserve and
store chemistry samples and TPM filters.
Process sediment trap samples;
rinse traps.
Wash filter holders, place in hood to dry. Set bottle bags out to dry.
Rinse and wipe coolers;
leave open to dry.
Rinse sample tubing with milliQ. Store tubing full of milliQ.
(reviewed 1/05 pkm)