Toxicity assessment of metals in sediment from the lower reaches of the Haihe River Basin in China

The aqueous environmental quality of the Haihe River Basin is crucial for the ecological health of local catchments and the Bohai Sea. For the routine management neglected sediment tests and no legitimate tool supported the toxicity evaluation yet, one supplementary monitoring was implemented to examine the occurrence and toxic level of sediment metals in the lower reaches of the Haihe River Basin in 2009. Both world-widely used consensus-based sediment quality guidelines and China's environmental quality standard for soils (EQSS) were used as assessment tools. Cu, Zn, As, Hg, Cd, and Pb were detected in all 24 samples, while Cr was detected in 18 samples. Assessment results showed 9 samples were toxic and the most dominant toxic element was As. Although the river water quality is getting better, sediment metals have accumulated over thirty years due to continuous industrial development, with toxicity far beyond safety limitations. The highest toxicity levels were encountered in Binhai New Area, suggesting three rivers should be given priority for restoration. It is found that EQSS is also applicable for sediment toxicity assessment until a dedicated tool for Haihe River Basin is available, except for that EQSS is too conservative for Pb.