Sedimentary Records of Heavy Metal Pollution in Fuxian Lake, Yunnan Province, China: Intensity, History, and Sources

This study focused on the concentration change of heavy metals of sediment cores in heavily polluted north area and less polluted middle area of Fuxian Lake in Southwest China. On the basis of the analysis of Cu, Ni, Ti, V, Pb, Cd, and Zn concentration-depth profiles, the pollution history of heavy metals was studied using (137)cesium (Cs-137) dating. The sources of heavy metals were distinguished by normalization of their profiles to aluminum and analysis of heavy metal concentrations of potential source materials. Geoaccumulation index (I-geo) was used to quantify their contamination intensity. The results showed that all the heavy metals found in the Fuxian Lake sediments originated naturally before 1980s. Cu, Ni, Ti, and V were still mainly natural in the north lake after 1980s, Cu, Ni, Ti, V, and Pb were mainly natural in the middle lake at all time, but the concentrations of Pb and Zn in the north lake were influenced by industrial wastes from the phosphorus fertilizer factory and cement plants. In all the lake, the contaminations of Cd and Zn were the results of agricultural cultivation using a large amount of fertilizers and the atmospheric fallouts of dusts from cement plants. At present, the geoaccumulation indices showed that the Fuxian Lake sediments were moderately to strongly polluted by Cd in the middle lake, and unpolluted to moderately polluted by Pb and Zn and strongly polluted by Cd in the north lake. Moreover, the pollution intensities of Cd, Zn, and Pb have been increased since 1980s.