ALMN NAWQA Surface-Water Study
Bed-Sediment and Tissue Study
Selected trace elements and organic compounds were measured in
streambed sediments and fish tissue at a network of 19 sites.
This network was established as part of the NAWQA Program in the
ALMN Basin. The 19 sites were selected to provide a broad spatial
coverage within the Study Unit. Ten sites are co-located with the
Fixed-Site network. These 10 co-located sites were selected
to examine specific land-use related issues. The remaining sites
were selected downstream of small urban/industrial areas in the
basins (8 sites) and in a basin with low human population density
as a reference site (1 site).
Bed-sediment samples were used to assess the sediment-size
fraction less than 64 microns (0.064 mm) for trace elements, and
the less than 2 mm size fraction for organic compounds. Composite
bed-sediment material was collected from 10 to 15 depositional
areas at each site. Composite samples of 5 to 10 whole fish were
analyzed for synthetic organic compounds while composite samples
of dissected livers of 5 to 10 fish were used for the trace
elements analysis. Each composite consisted of only one species
of fish. The species of fish used for each analysis is recorded
in the data tables (see Data link below).
Duplicate composite samples were taken at two sites to compare
variation within a species at a site. At two sites duplicate
collection of two different fish species were made. Composite
samples of each species were analyzed from these sites to examine
between species variation.
A map showing the location of Bed-Sediment and Tissue Study
sites is available for viewing: