Temporal Trends in Gas-Phase Concentrations of Chlorinated Pesticides Measured at the Shores of the Great Lakes

• Published in: Environmental science & technology 1998-07, Vol.32 (13), p.1920-1927
• Main Authors: Cortes, Donald R, Basu, Ilora, Sweet, Clyde W, Brice, Kenneth A, Hoff, Raymond M, Hites, Ronald A
• Format: Article
• Language: English
• Subjects: Applied sciences; Atmospheric pollution; Atmospheric pressure; CANADA; Climate; COMPOSE ORGANOCHLORE; COMPUESTO ORGANICO DEL CLORO; ESTADOS DEL CENTRO NORTE (EUA); ETATS DU CENTRE NORD (EU); Exact sciences and technology; LAKE STATES OF USA; NORTH CENTRAL STATES (USA); ORGANOCHLORINE COMPOUNDS; PCB; PESTICIDE; PESTICIDES; PLAGUICIDAS; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Polychlorinated biphenyls; Temperature; Trends
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es970955q

Multiple regression was used to examine the temperature dependence and to elucidate temporal trends of atmospheric gas-phase partial pressures of 10 organochlorine pesticides at five sites near the Great Lakes. The relation ship of temperature to gas-phase partial pressures was examined using the Clausius−Clapeyron equation, and environmental phase-transition energies were calculated for each of the pesticides. A first-order rate constant for the decline in gas-phase partial pressures was estimated from the regression, and corresponding regional atmospheric half-lives were determined. The atmospheric half-lives of the hexachlorocyclohexanes ranged from 2.2 yr for γ-HCH at Lake Michigan to 7.3 yr for γ-HCH at Lake Ontario. The half-life for hexachlorobenzene ranged from 3.3 yr at Lake Michigan to 12 yr at Lake Superior. The half-life for p,p‘-DDT was less than 3 yr at Lakes Superior, Michigan, and Erie. A decreasing trend for chlordanes could only be discerned at Lakes Michigan, Erie, and Ontario, where half-lives ranged from 3.2 yr for γ-chlordane at Lake Michigan and Lake Erie to 9.2 yr for trans-nonachlor at Lake Ontario. Using these half-lives and atmospheric concentra tions, virtual elimination dates were estimated for the pesticides in the atmosphere. These virtual elimination dates ranged from about 2010 for p,p‘-DDT to about 2060 for hexachlorobenzene. This study provides evidence that regulatory controls on pesticides have been effective in reducing the concentration of organochlorine pesticides in the environment.