[Derivation and application of sediment quality criteria of Cd and Hg for the Xiangjiang River].

Sediment quality criterion (SQC) is the concentrations of sediment-associated contaminants that are unlikely to be associated with sediment toxicity or other adverse effects on benthic invertebrates. Thus, the derivation of SQC is crucial to protect benthic invertebrates, and can serve as the tool for scientific sediment management. Sediment, interstitial water, and plant samples were collected at 43 sampling sites from the Xiangjiang River, and metal concentrations were determined. Based on equilibrium partitioning approach, spiked sediment toxicity approach using Hyalella azteca, and background value approach, SQC for Cd and Hg in the Xiangjiang River was derived. Results showed that, SQC-L for Cd and Hg in the Xiangjiang River were 1.89 mg x kg(-1) and 0.13 mg x kg(-1) respectively, and SQC-H were 28.32 mg x kg(-1) and 0.79 mg x kg(-1) respectively. SQC were comparable to those in previous studies. Also, the reasonability of SQC was demonstrated by the heavy metal concentrations in plants, matching sediment chemistry and toxicity data for benthic invertebrates in the Xiangjiang River. To assess the sediment quality of Xiangjiang, metal concentrations in sediment samples were compared with the SQC. It was found that the proportion of sampling sites with Cd and Hg concentrations lower than SQC-L or higher than SQC-H was low, and 74.4% and 76.7% of sampling sites showed Cd and Hg concentrations between SQC-L and SQC-H.