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MERC – Membrane Filter Test Plan
5
Basic Water Quality:
A hand-held multi-parameter instrument will be used to measure temperature, salinity,
and dissolved oxygen of the water at each sample point (described above) as it is collected. This
is considered ancillary data and helps to characterize the ambient conditions during testing.
Total Suspended Solids (TSS):
At each time point, water will be collected by MERC before the test platform and after
the initial prefilter (#2 if used) while water will be collected by the vendor after each additional
filter used, an appropriate amount filtered, then analyzed for TSS. Sample analyses will be
conducted by the vendor.
Particle Size Distributions
At each time point, water will be collected before each filter and after the final filter, kept
cold and dark, then shipped overnight to a certified laboratory for next-day analysis of particle
size distribution. The size distribution of particles (range 0 – 2 mm) will be analyzed using the
laser light scattering method (ASTM D4464).
Phytoplankton
At each time point, 250 ml of unfiltered water upstream and downstream of the test
platform will also be collected (in an amber Nalgene bottle) to determine concentrations of
phytoplankton. These subsamples will be fixed with standard Lugol’s solution and
analyzed by
using a Zeiss IM inverted microscope with (1 ml to 500 µl depending on cell density) direct
counts under a Sedgewick rafter slide.
Zooplankton
At each time point, 500 ml of unfiltered water upstream of the test platform will also be
collected (in an amber Nalgene bottle) to determine concentrations of zooplankton. Total
concentration of organisms will be determined using standard techniques of fixation and
analysis. Zooplankton samples will be fixed with buffered, 10% formalin in 125ml Nalgene
bottles and transported to SERC for quantification. Total counts and general taxonomic
classification will be conducted under a dissecting microscope at approximately 25X. In the case
of samples containing high numbers of zooplankton such as the unfiltered or ‘control’, this assay
may involve subsampling and scaling to report concentrations in the form of numbers per cubic-
meter. Where numbers are very low, as may be if filtering is very effective, every organism in
the sample will be individually counted. Larval forms of invertebrates will be identified to
higher taxonomic levels such as order (e.g., Decapoda) suborder (e.g., Balanomorpha) or class
(e.g., Bivalvia). Adults will be identified to species in most cases.
Bacteria
One
liter of raw water will be collected in clean, labeled 1-liter bottles
upstream and
downstream of the test platform
. Each bottle will be sample-rinsed 3 times, the sample collected,
then the bottles placed in a cooler to keep dark and cool for immediate transport back to the lab
to be tested for total heterotrophic bacteria,
Escherichia
coli
,
Enterococci
, and
Vibrio
cholerae
.
To determine total bacterial densities, 1ml of water sample will be diluted and spread in triplicate
onto Marine Agar (MA) and incubated at 25ºC or room temperature for 5 days. Colony forming
units will be counted at day 3 and 5, and recorded as colony forming units (CFU) per 100 mL of