MOBILITY AND TRANSFER OF RESIDUAL HEXACHLOROCYCLOHEXANE (HCH) IN AQUATIC ENVIRONMENT

An investigation was carried out to study the mobility and transfer of HCH-residues in Yanjia lake, Hubei, China, from 1990-1993. By samplin g at different locations, the horizontal distribution of HCH-residues was determined; by sampling at different depths in the same location, the vertical mobility of HCH-residues and its penetration were measure d. The vertical profiles of HCH-residues in sediment showed a gradient distribution, which was reduced with the increase in depth. This was very similar in shape to the organic carbon and nitrogen content profi les. The penetration of HCH-residues was measured as 60cm approximatel y. Meanwhile, water, sediment (0-12cm), benthos and benthic fish colle cted from the lake were analyzed to determine the transfer of HCH-resi dues along aquatic food chain. The BCF values of HCH-residues indicate d that the bioaccumulation of HCH-residues in freshwater food chain st ill exsisted in spite of the banning of HCH since 1983. The maxium BCF value of HCH-residues in the liver samples of 5-year-old common carp was up to 61966 (calculated by beta-HCH).