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Organochlorine Compounds in Fish Tissue from the Connecticut, Housatonic, and Thames River Basins Study Unit, 1992-94
Water-Resources Investigations Report 98-4075
By James F. ColesOrganochlorine compound concentrations were assayed in the tissues of fish collected at 32 sites in the Connecticut, Housatonic, and Thames River Basins study unit during 1992–94. The study was part of a survey of organic and inorganic contaminants in biological tissues, a component of the U.S. Geological Survey's National Water Quality Assessment (NAWQA) program. Concentrations of 28 organochlorines were measured in composite samples of whole fish collected at the sites. The organochlorine compounds most commonly detected in the tissue samples were total DDT (sum of o,p '- and p,p '-DDD, DDE, DDT), total chlordane (sum of cis - and trans -chlordane, cis- and trans -nonachlor, oxychlordane, and heptachlor epoxide), and total PCBs (Aroclors 1242, 1254, and 1260).
At 31 sites, at least one component of total DDT was detected in fish tissue at concentrations greater than the method reporting limit of 5 micrograms per kilogram of wet weight. The highest concentration of total DDT detected in fish tissue was 300 micrograms per kilogram. Although total DDT was detected at all but one site, concentrations were lowest in areas of low population densities. The DDT metabolite p,p '-DDE was detected most frequently and at the highest percentage of all DDT components, possibly indicating that DDT inputs into the aquatic system were not recent. At 25 sites, at least one component of total chlordane was detected in fish tissue at concentrations greater than the reporting limit of 5.0 micrograms per kilogram. The highest concentration of total chlordane detected in fish tissue was 390 micrograms per kilogram.Concentrations of the total chlordane in fish tissue showed a strong positive correlation with the drainage basin population density for a site, supporting the premise that chlordane was used extensively in suburban and urban areas before its use was restricted. Of the components comprising total chlordane, trans -nonachlor (the least degradable component) was detected most frequently and at the highest concentrations, indicating that chlordane inputs into the aquatic system were not recent.
At 28 sites, total PCBs were detected in fish tissue at concentrations greater than the method reporting limit of 50 micrograms per kilogram of wet weight; the highest concentration measured was 72,000 micrograms per kilogram. Concentrations of total PCBs generally were high in fish from the largest rivers; the highest concentrations were in tissures of fish from the Housatonic River; concentrations in tissue samples from three sites exceeded 10,000 micrograms per kilogram. Although most PCBs in the Housatonic River are from a documented source, high concentrations of total PCBs at other large river sites probably originate in the urban and industrial areas along these rivers.Back to CONN NAWQA Home Page |
URL: http://ct.water.usgs.gov/NAWQA/abstracts/wrir984075.htm Comments and feedback: NH/VT webmaster-nh@usgs.gov Last Updated December 19, 2006 |