Global chemical fate of alpha-hexachlorocyclohexane. 1. Evaluation of global distribution model

• Published in: Environmental toxicology and chemistry Vol. 18; no. 7; pp. 1390 - 1399
• Main Authors: Wania, F, Mackay, D, Li, Y.F, Bidleman, T.F, Strand, A
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Periodicals, Inc 01.07.1999; SETAC
• Subjects: Applied sciences; Atmosphere; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Evaluation; Exact sciences and technology; Global distribution model; Global environmental pollution; HCH (pesticide); marine environment; Ocean; pollutants; Pollution; Pollution, environment geology; soil; α-Hexachlorocyclohexane; Subtropical zone; Insecticide; Pollutant behavior; Tropical zone; Pesticides; Air water interface; HCH; Modeling; Climatic zone; Temperate zone; Persistence; Transport process; Compartmental model; Pollution; Medium effect; Organochlorine compounds; Chlorine Organic compounds; Environment; Air pollution; Water pollution; Polar region; Seawater
• ISSN: 0730-7268; 1552-8618
• DOI: 10.1002/etc.5620180707

Vertical atmospheric layering is included in a previously described, zonally averaged global multimedia distribution model. This model is used to simulate the fate of alpha-hexachlorocyclohexane (alpha-HCH), the main ingredient of the technical HCH pesticide mixture, for the 50 years of its large-scale use (1947-1997). Worldwide historic emission estimates are compiled, assigned to 10 climate zones, and used as input in model calculations. The performance of the model is evaluated by comparing calculated and measured concentrations in the atmosphere and seawater. A major focus is on the arctic and northern temperate environment, and emphasis is also placed on absolute levels, time trends, latitudinal profiles, and air-water exchange. In general, simulated and observed concentrations agree within one order of magnitude. Deviations are explained by the zonal averaging characteristics of the model and uncertainties associated with the environmental degradation rates of alpha-HCH. In both model results and observations, the dramatic decrease in the global emission of alpha-HCH is reflected in rapidly decreasing concentrations in the atmosphere and seawater, except in the Arctic Ocean, which apparently is the last refuge for alpha-HCH in the global environment. The model thus provides an illustration of the response characteristics of the global system to the reduced emissions of alpha-HCH. Its application to other chemicals with reduced emission is discussed.