Historical records of multiple heavy metals from dated sediment cores in Lake Chenghai, China

In this study, the temporal evolution of heavy metal contamination in the sediments taken from Lake Chenghai, China, in the recent 60 years, has been examined using the methods of ¹³⁷Cs dating, PIRLA procedure, geochemical normalization and calculation of enrichment factor. Fe and Al, the primary lithogenic components, were used as reference metals as usual. Most of all, natural post-deposition of Cr and Ca could mainly reflect the alternation of natural sources. The heavy metal concentration profiles suggests that the historical metal deposition in the sediment cores reflects the known history of atmospheric deposition of Cr, Ni, and Zn in South China, with an onset of increasing anthropogenic metal accumulation of Pb, Ni, Cu and Zn from non-point and point pollutions in the late 1970s and early 1990s. Statistical results by correlation analysis, principal component analysis and cluster analysis suggest that the influences of sedimentary organic matters on changes in metals concentrations maybe largely controlled by the trophic status in the system and that atmospheric deposition from coal and mine industry could affect the variation in sedimentary metals concentrations.