贵州典型城市河流表层沉积物汞生态风险研究

遵义湘江河是流经遵义市主城区的典型城市河流,为评价遵义湘江河的汞污染状况,系统采集河流表层底泥并进行分析。结果表明:沉积物汞含量为0.131～3.132 mg/kg,平均汞含量为1.049 mg/kg,河水和沉积物汞含量上游低于下游,汞含量与流经市区距离呈显著正相关。沉积物的甲基汞含量为2.1～31.4 ng/g,占总汞的比例为1.11%～1.87%,略高于其他地区。汞的BCR形态分析表明,沉积物中的汞主要以残渣态为主。生态风险分析表明,湘江河属于轻度污染但存在较大的潜在生态风险。

ECOLOGICAL RISK OF MERCURY IN SURFACE SEDIMENTS OF TYPICAL URBAN STREAM IN GUIZHOU PROVINCE

Xiangjiang River is a typical urban stream flowing through the main urban area of Zunyi. To evaluate the pollution characteristics and ecological risk of mercury of Zunyi Xiangjiang River, the surface sediments system were collected and analyzed. The results showed that the mercury content of surface sediments was ranged in 0.131~3.132 ng/g and the mercury content in downstream of both river water and sediments was much higher than upstream, and was positively correlated with the distance passed though urban areas. The methyl mercury concentration of surface sediments was ranged in 2.1~31.4 ng/g and accounted for 1.11%~1.87% of the total mercury. Furthermore, the results of BCR three-step sequential extraction procedure showed that the mercury in the sediment was mainly in the form of residue. The risk assessment indicated that the Xiangjiang River was mildly polluted while it had considerable potential ecological risk.