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U.S. GEOLOGICAL SURVEY
Open-File Report 99-57
In response to concern about recent blooms of the dinoflagellate, Pfiesteria piscicida, samples of sediment and water were collected from the lower Pocomoke River Basin and were screened for trace elements, pesticides, and other organic compounds. A large group of steroid and fatty acid methyl-ester compounds was detected in streamwater using gas chromatography/mass spectroscopy in scan mode. Some of these steroid compounds have been identified and further quantified in bed-sediment extracts. Spatial patterns of the concentrations of cholesterol suggest that these compounds are linked to the runoff of animal wastes into the river. Many of the organic compounds found in the Pocomoke River sediments have not yet been identified, but at least several are in the class of hormone compounds related to estradiols and have the potential to promote endocrine-disrupting effects in aquatic life. Particulate forms of arsenic and zinc are slightly elevated above normal levels for streams, but the sources for these elements are still undetermined. Several pesticides were found in low, parts-per-trillion concentrations, but were within the ranges commonly found in streams of this region.
Abstract
Introduction
Background
Description of Study Area
Acknowledgments
Sample Collection and Handling
Analysis of Samples
Field Conditions at Time of Sampling
Results of Trace-Element Analysis
Results of Organic-Compound Analysis
Summary and Implications
References Cited
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For more information about USGS activities in Maryland, Delaware and the District of Columbia contact:
Director
MD-DE-DC Water Science Center
U.S. Geological Survey
8987 Yellow Brick Road
Baltimore, MD 21237
Telephone: (410) 238-4200
Fax: (410) 238-4210
or access the USGS Water Resources of Maryland, Delaware, and District of Columbia home page at: http://md.water.usgs.gov/.
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