三峡库区沉积物中重金属化学形态分布特征与相关性分析

为全面了解三峡库区干支流沉积物中重金属的赋存形态,更好地为评价及保护三峡库区水生态环境提供科学依据,于2015年6月在三峡库区采集沉积物样品67个,通过ICP-MS等仪器测定了沉积物中各重金属元素的不同赋存形态量,运用SPSS、Matlab统计分析软件对重金属赋存形态进行对比分析。结果表明,库区表层沉积物中Cr、Ni元素主要以残渣态为主(占总量的75%以上);Cu、Zn、As元素主要以残渣态和可还原态为主(合计占总量80%~95%);Cd元素主要以酸可提取态和可还原态为主(分别占总量的55%和23%);Pb元素主要以可还原态和残渣态为主(各占总量的71%和18%)。Cd和Pb元素生物可利用态量较高,均超过该元素的长江沉积物背景值;该种形态下的重金属元素容易进入水体,并且在地球化学条件变化时转化成能被生物吸收和利用的形态,对生物造成较大危害。干流上游段重庆主城区及下游段,渠系河、大宁河、磨刀溪、沿渡河应当是重金属生态危害研究与防治的重点区域。

Chemical Specifications of Heavy Metals in Sediment of the Three Gorges Reservoir and Their Correlation Analysis

This paper investigated the chemical speciation of heavy metals in sediments of the main streams and tributaries of the Three Gorges Reservoir in attempts to provide a guidance to evaluationand protection of the eco-logical environment in the reservoir. We took 67 samples from sediments in this area in June, 2015 and analyzed them using ICP-MS in which the chemical speciation of the heavy metals was measured. The measured data were analyzed using the SPSS software in the Matlab. The results are as follows.①Cr and Ni in the surface sediment were mainly composed of residual fraction, accounting for more than 75％of their overall total contents.②Cu and Zn were mainly composed of residual and reducible fraction, accounting for 80％～95％of their total contents.③Cd was mainly acid extractable and reducible, accounting for 55％and 23％of its total content respectively.④Pb was mainly reducible. We also found that the content of bioavailable Cd and Pb in the sediments is higher than their background value in sediments of the Yangtze River. Since bioavailable Cd and Pbare mobile in water and biogeochemically active, they are biologically harmful. The key areas prone to heavy metal pollution and need further research are the upper- and down-reaches of the Yangtze river, including the urban area of Chongqing, Quxi River, Da'ning River, Modao River and Yandu River.