袁时珏+张道方

摘要：通过改变上覆水体pH和溶解氧，并采用改进的由欧共标准测量与检测局（BCR）提出的连续提取法，研究pH和溶解氧对蕴藻浜沉积物中Cu、Cr释放的影响，以及沉积物释放前后Cu、Cr形态的变化，探索沉积物中重金属释放的机理.结果表明：随着pH增加，沉积物中重金属释放量下降，可还原态在沉积物中的含量上升，可氧化态与酸可提取态含量均有下降，这主要和H+与重金属离子的竞争以及沉积物中自然胶体的吸附有关；随着溶解氧含量增加，沉积物中重金属释放量升高，可氧化态含量呈明显下降趋势，而可还原态含量略有上升趋势，这主要与沉积物的还原性、硫化物及铁锰氧化态重金属有关.

关键词：pH； 溶解氧； 沉积物； 释放； Cu； Cr

中图分类号： X 52 文献标志码： A

Abstract：In this paper，effects of pH and dissolved oxygen（DO） on Cu and Cr release in the sediment from Yunzaobang River in Shanghai were studied by adjusting pH and concentration of the dissolved oxygen in the overlying water.The changes of Cu and Cr speciation in Yunzaobang River sediment were also analyzed and compared using the modified BCR sequential extraction method to explore the release mechanism.The results showed that with the increased pH，both Cu and Cr release from the sediment decreased.The percentage of the reducible form increased.But the percentage of the oxidizable form and HAc soluble form reduced，which was related to the competitive relation between H+ and metal ion as well as adsorption of the colloid in the sediment.With the rising concentration of DO，both Cu and Cr release increased.The percentage of the oxidizable form reduced obviously while that of the reducible form rose slightly，owing to the reducibility of the sediment itself as well as the existence of sulfide and FeMn oxides in the sediment.

Keywords：pH； dissolved oxygen； sediment； release； Cu； Cr

上海是具有悠久历史的工业化大城市，其人口密度高，排污总量大，污染负荷重，水环境问题也尤为突出.河道沉积物是河流生态系统的重要组成部分，也是各类污染物的载体，特别是重金属污染物的蓄积库.长期以来，沉积物与水体之间存在着密切的能量和物质交换[1]，沉积物的污染状况也是衡量河道水环境的重要指标.

重金属主要通过人为来源（生活及工业排污）和自然来源（大气沉降[2]、海洋来源[3]、陆地风化[4]等地化学活动）进入河道水体.水体中有机质等胶体通过吸附、络合、絮凝、沉降等作用富集在沉积物中，一旦水体环境条件发生改变，水-沉积物界面的动态平衡会被打破，易使得……