Concentrations and Fluxes of Chloroiiaplithalenes in Sediment from Lake Kitaura in Japan in Past 15 Centuries

摘要

The concentrations of 63 congeners of chloronaphthalene (CN; polychlorinated naphthalenes, PCNs) in dated on ～500 B.C. to 2000 sediment core from the Lake Kitaura in Japan have been quantified by HRGC/HRMS after double column HPLC fractionalion. Sediment from the Lake Kitaura showed a time-dependent pattern in distribution of CNs since the ～500 B.C. Starting from the 1910s the total CNs content increased accelerating from the 1960s, and, in parallel, the pattern of CN congeners has changed with a substantial increase in contribution from the penta, hexa, hepta, and octaCN. The total CNs content normalized to dry weight of sediment peaked out in the layer dated on 1984-1985, and next nearly two-fold decreased with further gradually decreasing concentration in 1987-2000. An occurrence of tri and letraCNs in deep sediment layers corresponded to preindustrial synthesis and use of CNs seems to be connected to relatively greater water solubility and mobility in the pore water of those CN homologue groups. Based on CN congener pattern and results of multivuriate analysis three main layers were separated in the sediment core. Starting from 1981 the emission sources related to combustion marker congeners become substantial contributors to flux of annually deposited CNs, while relative significance of the evaporative source marker congeners decreased after 1985. The annual flux of CNs into sediments of the Lake Kitaura was 0.073-031 pg/cirr before 1926, increased to 5.5-14pg/em2 in 1963 1970 and next sharply increased to 50-107 pg/ cm2 in 1971-1985, and after that decreased to 17pg/cnr in 1997-2000.