• 关键词：北京  温榆河  沉积物  重金属  风险评估

• 基金项目：国家“十五”科技攻关课题(No.2004BA516A19);北京市自然科学基金重大项目(No.8000001)

• 李莲芳
• 1. 中国农业科学院农业环境与可持续发展研究所, 北京 100081; 2. 农业部农业环境与气候变化重点开放实验室, 北京 100081; 3. 中国农业大学资源与环境学院, 北京 100094

• 曾希柏
• 1. 中国农业科学院农业环境与可持续发展研究所, 北京 100081; 2. 农业部农业环境与气候变化重点开放实验室, 北京 100081

• 李国学
• 中国农业大学资源与环境学院, 北京 100094

• 梅旭荣
• 1. 中国农业科学院农业环境与可持续发展研究所, 北京 100081; 2. 农业部农业环境与气候变化重点开放实验室, 北京 100081

• 摘要：河流沉积物是水环境的基本组成部分,其重金属含量常被作为水环境质量的重要指标之一.本研究探讨了北京市温榆河流域沉积物中重金属的累积特征,并采用沉积物富集系数、Hakanson潜在生态风险指数等方法评估了几种重金属的环境风险,简要分析了其主要来源.研究结果表明,温榆河流域沉积物中Ni和Cd的含量分别为19.9～41.4mg·kg^-1和1.19～1.67mg·kg^-1,其值介于LE-L值(最低效应水平)与SE-L值(严重效应水平)之间.根据SQG标准,温榆河表层沉积物中的重金属含量处于中度污染水平,可能会对水域生物产生一定的负面影响;而高毒元素As的含量已非常接近LE-L值,应成为下一步重点防控的对象.采用沉积物富集系数法分析,发现80%以上的样点出现了重金属的富集,且毒性强的重金属As、Cd的富集累积较为严重,根据Fe与重金属含量间的相关性,可知沉积物中Zn、Cu、Cr主要为天然地球化学来源,而Cd、As、Ni则主要来源于人为污染.以北京市土壤背景值作为参比进行分析,发现各取样点的表层沉积物均呈现出强至极强的生态风险,参与评价的5种重金属生态风险由强到弱的顺序依次为Cd、As、Cu、Cr、Zn.

• Abstract：Heavy metals are often regarded as very important parameters reflecting sediment quality since river sediment is an essential component of water environment. In this paper, the characteristics of heavy metal enrichment in Wenyu River sediment were surveyed. The environmental risk assessment was conducted systematically using such methods as Sediment Enrichment Factors and Hkanson potential ecological risk index, and the underlying source of heavy metals was analyzed. The results indicated that concentration ranges of Ni and Cd were 19.9～41.4 mg·kg^-1 and 1.19～1.67 mg·kg^-1 . According to Sediment Quality Guidelines, Wenyu River sediment was moderately contaminated by Cd and Ni since their concentrations were just between LE-L (Lowest effect level) and SE-L (Severe effect level) values, which may result in negative biota effects in the watersheds. Besides, toxic element arsenic concentration in sediment was very close to LE-Lvalue and more emphasis should be placed on arsenic control in the next step. Using enrichment factor method, heavy metal enrichment was observed for more than 80% of the sampling points, and relatively high enrichment of toxic elements As and Cd was obtained. In terms of the correlation between Fe and heavy metals content in Wenyu River sediment, it was recognized that Zn, Cu and Cr mainly originated from natural sources while the content of Cd, As and Ni in Wenyu River sediment was mainly influenced by anthropogenic activities. Compared to soil background values of Beijing, the heavy metals in Wenyu River sediment showed very strong ecological risk, and the ecological risk of five heavy metals was in the descending order of Cd、As、Cu、Cr、Zn.

• Key words：Beijing  Wenyu River  sediment  heavy metal  risk assessment

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