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Global chemical fate of α-hexachlorocyclohexane. 2. Use of a global distribution model for mass balancing, source apportionment, and trend prediction



A global distribution model that was previously shown to give satisfactory results is used to study in more detail and quantitatively the fate of α-hexachlorocyclohexane (α-HCH) in the global environment. The results provide a comprehensive historical picture of the global behavior of this chemical, which after being used in huge amounts in the early 1980s, has since been essentially eliminated. The major pathway of α-HCH from a global perspective is the transfer from the site of application to the world oceans via rivers and the atmosphere. Major reservoirs were initially the soils in regions of application and are now the world oceans. Global distribution patterns can be explained by differential persistence in various climates and meridional transport in the atmosphere and oceans. Most of the α-HCH emitted globally has been degraded in the zones of application, and only very small fractions, probably less than 1%, have survived until the mid−1990s and have reached the Arctic. However, a large fraction of the α-HCH that has survived is now present in high latitudes. The Arctic Ocean as the final reservoir for α-HCH is likely to be slowly depleted, with a half-life of approximately one decade.

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