Sixty-year sedimentary records of polymetallic contamination (Cu, Zn, Cd, Pb, As) in the Dahuofang Reservoir in Northeast China

The sedimentation rate (by 210Pb and 137Cs dating), sediment characteristics, contamination and accumulation history of trace metals (Cu, Zn, Cd, Pb and As) were studied for sediments from Dahuofang Reservoir, which is the most important source of drinking water in Northeast China. The results indicated that the variation of sediment grain size has shown typical river-type, layoff period and lacustrine-type sediments characteristic, which is in accordance with the building and operation history of Dahuofang Reservoir. Concentrations of the five elements showed an increasing trend with a fluctuation in mid-1990s. Especially after 1975, the contaminations became more severe. Relationships between the elements and sediment parameters suggested that the increased level of contaminations of trace metals after 1975 occurred mainly as a result of anthropogenic input, including the mining and smelting of Cu at the upstream of Hun River, as well as the industrial, agricultural and economic activities around Dahuofang Reservoir after the “Reform and Open” policy embarked by China in 1978. Accumulation state of these elements was investigated based on the enrichment factors. In the whole study period, enrichment of Pb and As was minimal; Cu and Zn enrichment was moderate; Cd enrichment was moderate, but with significant aggregation in recent years.