USGS Fact Sheet 067-97:
Pesticides in Selected Small Streams
in the Puget Sound Basin, 1987-1995
Pesticides Detected in Streambed Sediments
Of the total number of
compounds detected in streambed sediments, most were insecticides or
insecticide degradation products. Six of the nine pesticides detected
in streambed sediments were insecticides (or their degradation
products), two were herbicides, and one a fungicide. The most
frequently detected compounds in sediments, found in both urban and
agricultural streams, were PCP, detected in five streams, and DDT
and/or its degradation products DDD and DDE, detected in three
streams. Chlordane was also detected in sediments. DDT, PCP, and
chlordane are currently banned from use in the U. S., but were heavily
used in the past. Because of their slow degradation rates, these
pesticides are likely to be present in sediments for many years. DDT
was used as an insecticide; PCP was used primarily as a fungicide, but
also as an insecticide and herbicide. Other pesticides found in bed
sediments from at least two streams were the herbicides dichlobenil
and dicamba. The insecticides chlordane, diazinon, and endosulfan were
identified in one stream each. The graph below shows that nine
compounds were detected at concentrations either as estimated or
quantifiable values. Pesticides in bed sediments do not have any State
freshwater sediment-quality criteria, but USEPA guidelines to protect
benthic organisms are proposed for DDT, chlordane, and endosulfan in
bed sediments (Nowell and Resek, 1994). These guidelines, which are
based on the amount of organic carbon in the sediments, do not apply to
concentrations shown in the graph.
Click here for a graph of concentrations
of pesticides detected in bed sediment
Puget Sound Basin NAWQA home page is
<http://wa.water.usgs.gov/projects/pugt/>
This page is http://
wa.water.usgs.gov
/pubs/fs/fs067/pest.d.html
Last modified: Mon Jun 9 17:25:40 1997
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