巢湖表层沉积物重金属的分布特征及生物有效性

Distribution Characteristics and Bioavailability of Heavy Metals in Surface Sediments of Chaohu Lake

为分析沉积物中重金属的分布特征、相互关系及其可能来源,以安徽巢湖表层沉积物为研究对象,利用原子吸收分光光度法(AAS)测定5种重金属(铅、铜、镍、锌、镉)总量和同步浸提重金属(SEM)含量,同时测定酸可挥发性硫化物、总氮、总磷、总有机碳等多种指标,利用低影响程度(ER-L)和中影响程度(ER-M)基准值,[∑SEM]/[AVS]模型和[∑SEM]-[AVS]模型,判断预测表层沉积物中重金属的生物有效性。结果显示:重金属总量在全湖的空间分布不均匀,具有入湖口大于湖心的特征,共8个指标超过ER-L基准值,西湖区各金属总量大于东湖区,两者之间具有显著性差异(P<0.05),全湖[∑SEM]/[AVS]的值在1.097～2.076之间,但[∑SEM]-[AVS]的变化范围为0.127～0.996μmol/g;表明重金属Cu、Cd污染较严重,人为输入影响大,AVS对重金属的束缚作用有重要影响,大部分表层沉积物中的重金属生物有效性低。

In order to analyze the distribution characteristics,relationships and the possible sources of heavy metals（HMs） in sediments,total amount of five kinds of HMs（lead,copper,nickel,zinc and cadmium） and its simultaneously extracted metals（SEM） in the surface sediments of Chaohu lake were measured by atomic absorption spectrophotometer（AAS）.The acid volatile sulfide（AVS）,total nitrogen,total phosphorus,organic carbon were also determinated.Basic value of effects range-low（ER-L） and effects range-median（ER-M）,/ model and- model were used to predict the bioavailability of HMs in surface sediments.The results showed that spatial distribution about the total concentration of HMs in sediments was uneven,that were characterized by stream outlet the lake center,and eight indices were more than ER-L benchmark.The total amount of HMs in the western zones of lake was higher than the eastern zones of lake,and the relationship between two zones of the lake was significant difference（P0.05）.The range of [∑SEM/AVS] was from 1.097 to 2.076,but - varied between 0.127 μmol/g and 0.996 μmol/g.The results suggested that the pollution of Cu and Cd was serious,and anthropogenic inputs were more influencing factor.AVS played an important role in binding the HMs,and the bioavailability of most HMs in sediments was low.