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SOP6 – Water Quality Analysis
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7.2.4. Whole-Water Reservoir – POC, DOC, and Chl-a
Samples are collected via an integrated flow system controlled by a flowmeter and filled over the
entire course of the fill/discharge operation of each tank. The sampling rate of the whole-water
is 1.5 L minute
-1
at 300 m
3
hour
-1
ballast-flow-rate (less as flow-rates decrease). A whole-water
(not filtered) sampling-rate reference table (Table 4.2) is posted in the sample van (see section
4.5). Water is collected in a 100L conical bottom, fiberglass, algal-culture cylinder (referred to
as whole water reservoir) and aerated to keep entire water column well mixed and in suspension.
Once the whole water reservoir is filled, sample rinse the carboy three times and then fill the
carboy with water from both the control and treated reservoirs. Immediately transport the carboy
to the science laboratory for immediate filtering for POC, DOC, and Chl-a.
7.3. Filtration Field Methods
Each type of filtration analysis has its own labeled foil packet for the filters post-filtration. The
filters are labeled with the trial name number, and sampling type, type of analysis/filter, date, and
amount of water filtered (Figure 7.1),
Figure 7.1. Illustration demonstrating the proper way to label a foil packet.
Each type of analysis has its own bag for foil packets post-filtration labeled with: MERC, trial
name number, and sampling type (such as STDN-01-UT {UT = uptake}), date, and number and
type of filters (such as 11 pkts - Chl-a). The sample bottles are not emptied until filtering has
been completed.
7.3.1. Chlorophyll-a – using NASL filtering protocols
(see Appendix A)
Filter whole-water within a few hours. Filter each sample for triplicates. Using forceps, place a
47 mm GF/F filter pad (nominal pore size is 0.7 microns), on the frit and cover with the cup.
Use the vacuum pump suction to help place the pad.
Vigorously shake the sample bottle to uniformly resuspend the particulates. Sample rinse a to-
deliver graduated cylinder. Shake bottle again.
Measure a known amount into the cylinder and immediately pour into the filter, filtering enough
water so only a faint color appears on the pad (except when water is tinted, then coordinate with
NASL).
Suck to dryness at about 8 inches HG on the vacuum pump gauge. Using forceps and without
touching the filtered area, fold filter in half with the material on the inside and place into a
labeled foil packet. The label includes sample ID, date collected and volume filtered. Place into
labeled bag and freeze at -20°C.
MERC TSS
Trial Name:
Analysis:
Date:
____ mL