抄録
The persistent organochlorines such as PCBs, DDT compounds and HCH (BHC) isomers were detectable all over the environmental media and biota, in which much higher levels were found in agricultural soil, coastal sediment and biological samples due to their hydrophobic, lipophilic and less biodegradable properties. These pollutants extend the boundaries of distribution over the global environment, being evidenced by their occurrence in Antarctic atmosphere, hydrosphere and biosphere. In open ocean environment, organochlorine contamination is much more prominent in northern hemisphere than in southern hemisphere. The open ocean water serves as a vast reservoir and final sink of these persistent organochlorines. The clearance rate of these chemicals from surface to deeper layer in open ocean water columns is relatively slower in tropical waters than in high latitude ones. This implies the possible prolonged contamination of persistent organochlorines in the tropical marine environment, even if their uses would be stopped in the future. The bioaccumulation processes in marine organisms depend primarily on the physicochemical and biochemical properties of organochlorines and the metabolic capacity and life-span of organisms. The species-specific drug metabolizing enzymes might be related to the differencial ecotoxicity of xenobiotics in wild animals. Of these organochlorines, PCBs are most noticeable chemicals in view of the future trend of environmental contamination. About two thirds of cummulative production of PCBs are still in use mainly for electrical equipments. The pertinent measures to prevent the further discharge of PCBs are required to reduce the present status of contamination in abiotic and biotic environment.
