湘江沉积物镉和汞质量基准的建立及其应用

沉积物质量基准是保护底栖生物免受污染物危害的保护性临界水平,可用来评估与沉积物结合的污染物的影响,并为底栖生物保护和沉积物的科学管理提供依据.分析了湘江43个采样点沉积物、上覆水、间隙水和植物中Cd和Hg含量,选取钩虾做沉积物毒理实验,利用相平衡分配法、加标毒理实验法和背景值法确定湘江沉积物Cd和Hg质量基准低值(SQC-L)分别为1.89 mg·kg-1和0.13 mg·kg-1,基准高值(SQC-H)分别为28.32 mg·kg-1和0.79 mg·kg-1.经与国内外基准值比较,并与底栖生物监测数据和植物监测数据对比分析,表明确定的基准值合理.应用该基准值评价湘江沉积物质量现状发现,湘江沉积物Cd和Hg含量低于SQC-L和高于SQC-H的采样点所占比例较低,74.4%和76.7%的采样点沉积物Cd和Hg含量在SQC-L和SQC-H之间.

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·kg^-1 and 0.13 mg·kg^-1 respectively, and SQC-H were 28.32 mg·kg^-1 and 0.79 mg·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.