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In cooperation with the U.S. Environmental Protection Agency

A Chronicle of Organochlorine Contamination in Clear Creek, Galveston and Harris Counties, Texas, 1960–2002, as Recorded in Sediment Cores

By B.J. Mahler and P.C. Van Metre

U.S. Geological Survey
Fact Sheet 088–03

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Clear Creek

Key Findings

Collection and Age Dating of the Sediment Core

Trends in Chlordane and Other Organochlorine Compounds



DDD and Dieldrin

Other Organochlorine Compounds

What Can We Conclude About Organochlorine Compounds in Clear Creek?




1. Map showing location of Clear Creek watershed and coring sites and insets of coring sites CCA and CCD, selected for more intensive analysis
2–4. Graphs of
2. Cesium-137 profiles in sediment cores CCA and CCD indicate undisturbed sediment dating back to pre-1964
3. Concentrations of chlordane in sediment cores CCA and CCD and in blue crabs and bottom-feeding fish
4. DDE, a breakdown product of DDT, and total PCB show pronounced historical trends, with peaks in sediment cores CCA and CCD coinciding with the period of peak use



Concentrations of selected organochlorine compounds in two Clear Creek sediment cores


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