基于梯度扩散薄膜技术的太湖金属和营养盐区域污染特征分析

摘要

本研究利用梯度扩散薄膜技术（Diffusive gradients in thin-films，DGT）对太湖7个湖区的水体和沉积物中金属与营养盐有效态含量进行原位监测，并分析污染物的区域特征。结果表明，DGT所测有效态浓度低于传统化学方法所提取浓度，且能实现低浓度、多元素同时监测。具体来看，太湖水体中金属的DGT有效态含量较低，区域差别较小。沉积物中9种典型金属的DGT有效态含量排序为Fe>Mn>Zn>Ni>As>W>Co>Mo>Cu，其中，Fe、As、Zn、Ni和W在竺山湾、梅梁湾和贡湖污染相对较重，在湖心区、胥湖和东太湖污染相对较轻，其余金属分布较平均且含量较低。与金属不同的是，太湖水体中DGT所测的有效磷（P）含量整体较高，最高值出现在贡湖，达83.2μg·L-1。沉积物中DGT有效态P的区域分布更明显，以竺山湾、梅梁湾和沿岸区污染相对较重，最高值出现在竺山湾，达500μg·L-1。对比沉积物和水体中DGT有效态P含量发现，竺山湾、梅梁湾和沿岸区沉积物可能是P的主要储存场所，具有潜在释放风险。%Concentrations of metals and nutrients in water and sediments from 7 different regions in Lake Taihu were measured using in situ diffusive gradients in thin-films(DGT)technique. Their regional pollution characteristics were evaluated. Results showed that the concen-trations of metals and nutrients measured by DGT were lower than those by chemical extraction. Simultaneous measurements of multiple ele-ments at ultra-low concentration levels were obtained using DGT. No obvious differences were found in DGT-measured concentrations of metals in water among 7 regions, while large differences were observed in DGT-measured concentrations of metals in sediments among these regions. Iron, As, Zn, Ni and W were heavily polluted in Zhushan Bay, Meiliang Bay and Lake Gong, compared to the central Lake, Lake Xu and East Lake Taihu. Overall, the order of DGT-measured concentrations of metals in sediments was Fe>Mn>Zn>Ni>As>W>Co>Mo>Cu. Unlike metals, the average P concentrations measured by DGT in water were high, with the highest value(83.2μg·L-1)appeared in Lake Gong. As for DGT-measured P in the sediments, Zhushan Bay, Meiliang Bay and Coastal region were heavily polluted, with the highest val-ue of 500μg·L-1 detected. By comparing P concentrations in sediments with those in water, it was found that the sediments in Zhushan Bay, Meiliang Bay and Coastal region probably acted as P sources, which potentially released P to the overlying water.