Similar Rates of Decrease of Persistent, Hydrophobic and Particle-Reactive Contaminants in Riverine Systems

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• 作者：Peter C. Van Metre ; Jennifer T. Wilson ; Edward Callender ; and Christopher C. Fuller
• 刊名：Environmental Science & Technology
• 出版年：1998
• 出版时间：November 1, 1998
• 年：1998
• 卷：32
• 期：21
• 页码：3312 - 3317
• 全文大小：93K
• 年卷期：v.32,no.21(November 1, 1998)
• ISSN：1520-5851

文摘

Although it is well-known that concentrations of anthropogenic radionuclides and organochlorine compoundsin aquatic systems have decreased since their widespreadrelease has stopped in the United States, the magnitude andvariability of rates of decrease are not well-known.Paleolimnological studies of reservoirs provide a tool forevaluating these long-term trends in riverine systems. Ratesof decrease from the 1960s to the 1990s of ¹³⁷Cs, PCBs,and total DDT in dated sediment cores from 11 reservoirsin the eastern and central United States were modeledusing first-order rate models. Mean half-times of 10.0 (±2.5),9.5 (±2.2), and 13 (±5.8) yr for decay-corrected ¹³⁷Cs,PCBs, and total DDT, respectively, are surprisingly similar.Similar rates of decrease in a few reservoirs are alsodemonstrated for chlordane and lead. Conceptual andsimple mathematical models relating two soil distributionsof ¹³⁷Cs to trends in the cores provide insight intodifferences in trends between watersheds with differentland uses and suggest that trends are controlled by erosion,transport, mixing, and deposition of sediments. Theseresults, supported by similar trends reported for other settingsand environmental media, could provide an estimate ofthe decadal response time of riverine systems to changesin the regulation of other persistent hydrophobic or particle-reactive contaminants.