Accumulation of heavy metals in the lacustrine sediment of Longgan Lake, middle reaches of Yangtze River, China

Spatial and temporal distribution of heavy metals (Chromium, Copper, Nickel, Lead, and Zinc) in the sediment of Longgan Lake, middle reaches of Yangtze River, China were analyzed to discuss their enrichment characteristics and history in combination with geochronological data and to identify anthropogenic effects. The results showed that the enrichment state of heavy metals was higher in the western versus eastern lake area, although their concentrations behave in the opposite case, which demonstrated that stronger human activities existed in the western lake catchment. The enrichment history of heavy metals pointed out that prior to 1950, the enrichment state was lower in the ambient lake areas illustrating the natural effect on the lake; thereafter the human activities in the catchment enhanced markedly causing an increasing heavy metal enrichment. The increase of heavy metal enrichment in the 1970s occurred in the central lake areas. The temporal difference between the ambient and central areas elucidated that the heavy metal accumulation might be buffered by the lake before they entered the sediment. Correlation analysis revealed that there was a significant correlation between heavy metals in the sediment suggesting their similar sources. Heavy metals were distinctly related to aluminum, calcium, lithium, iron, and organic matters, which could denote their forms in the sediment.