南四湖表层沉积物中铍、锑、铊的地球化学特征与环境风险

南水北调工程是世界规模最大,同时也是受益人口最多的调水工程之一.南四湖是南水北调东线工程中最大的调蓄湖库.本文研究了南四湖表层沉积物中铍(Be)、锑(Sb)、铊(Tl)的含量分布与赋存形态特征,并结合多种方法评估了其环境风险.结合前人已取得的成果,定义了Be、Sb、Tl的毒性系数.研究表明,南四湖表层沉积物中Be和Sb的平均含量略高于环境背景值,而Tl的含量低于环境背景值.赋存形态分析表明,残渣态Be、Sb、Tl的占比分别超过了65%、70%、84%,而酸可溶态百分含量非常低,可移动性与生物可利用性均不强.结合上述风险评价方法可知,Be、Sb、Tl在南四湖表层沉积物中富集程度较低,生态危害性较小.Be、Sb、Tl均以自然来源为主,人类活动来源为辅.Sb的人类活动来源明显不同于Be和Tl,可能主要为大气沉降.Be、Sb、Tl在沉积物中的分布状况不同程度地受到粒度、有机碳、铝及铁锰氧化物等的制约.

Research on geochemical characteristics and environmental risk of Be, Sb and Tl in surface sediments of the Nansihu Lake

The South-to-North Water Diversion Project is one of the biggest water transfer projects with the largest beneficiary population in the world. Nansihu Lake is the biggest reservoir lake in the east route of South-to-North Water Diversion Project. This study analyzed contents distribution and speciation characteristics of beryllium(Be), antimony(Sb) and thallium(Tl) in surface sediments of the Nansihu Lake. Their environmental risks were evaluated by multiple methods. Based on the results given by the predecessors, the toxic response factors of Be, Sb and Tl were defined in this paper. The results showed that the average contents of Be and Sb were a little higher than their background values, and Tl content was lower than its background value. Speciation analysis showed that the residual forms of Be, Sb and Tl accounted for over 65%, 70%, and 84% respectively, while the contents of the acid soluble was very low which led to low mobility and bio-availability. The surface sediments of Nansihu Lake had low Be, Sb and Tl enrichment degree, and therefore the ecological risk was low. Be, Sb and Tl were mainly from nature and ancillary from human activity. Different from Be and Tl, the main human activity source of Sb might be atmospheric settlement. Distributions of Be, Sb and Tl in the sediments were affected by particle size, TOC, and Al/Fe/Mn to some extent.