Analysis of historical trend of heavy metal pollution recorded in a sediment core from Lake Nakaumi, Japan
2015
Kusunoki, K. (Shizuoka University, Shizuoka, Shizuoka (Japan). Division of Technical Service) | Sakata, M.
We measured the heavy metal (Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, V, and Zn) concentrations and Pb isotope ratios in a sediment core collected near the center of Lake Nakaumi. The results showed that Cu, Pb, and Zn pollution started in the 1890s-1900s, whereas Co, Cr, Mo, Ni, and V pollution started in the 1950s. It is likely that their pollution was caused by effluent from metal mining and metallurgical industries around the lake. Next, the sources of Pb more recently added to the sediment since the 1900s were evaluated using a two-component end-member model based on the Pb isotope ratios. The major sources of anthropogenic Pb in the 1900s-1930s, 1940s-1980s, and 1990s-2000s may have been the mining effluent of Japanese lead ores, the exhaust particles from the smelting of imported lead ores and vehicles using leaded gasoline, and aerosols transported from the Asian continent, respectively. Moreover, the contribution of Asian outflow to the increase in Cd, Sb, and Zn concentrations in the sediment around 2000 was estimated on the basis of rainwater data. The results suggest that the contribution of Asian outflow is large for Cd and Sb but not for Zn.
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