| 雅鲁藏布江中段表层沉积物重金属形态分布及风险评价 |
| 摘要点击 2785 全文点击 1425 投稿时间：2014-01-11 修订日期：2014-04-09 |
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| 中文关键词 重金属 BCR方法 赋存形态 风险评价 雅鲁藏布江 |
| 英文关键词 heavy metal BCR sequential extraction procedure speciation distribution ecological risk assessment the Yarlung Zangbo River |
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| 中文摘要 |
| 采用了欧共体BCR分步提取的方法，对西藏雅鲁藏布江中段人口密集区的表层沉积物中的9种重金属元素（Cd、Co、Ni、Cu、Zn、Pb、Cs、As和Cr）不同赋存形态进行了研究，分析了其形态分布特征. 并分别用风险评价编码法（RAC）和沉积物质量基准系数法（SQG-Q）对沉积物重金属生物有效性进行了风险评价. 结果表明：① 元素Cr、As主要赋存于残渣态（占87%~96%），Ni、Cu、Co和Cs赋存特征较为相似，来自非残渣态约占20%，元素Cd酸可提取态和可还原态约占65%，表现出较高的生物毒性；②由 RAC评估得出 元素Cd有效态占37.38%，对环境构成高风险等级，元素Co、Ni、Cu和Zn对环境的危害处于低风险状态，元素Pb、Cs、As和Cr处于无风险状态，单从重金属形态的生物有效性评价，雅江沉积物对环境构成的风险排序为Cd>Co>Ni>Cu>Zn>Pb>Cs>As>Cr；③ 沉积物SQG-Q系数为0.804，具有中度的潜在生物毒性效应，鉴于该研究重金属元素主要赋存于残渣态，并且重金属平均含量除元素Cr和Ni外，其余元素均小于TEL和PEL值，所以，该河段总体上处于较低的风险等级，受到人为污染活动较少，污染程度较低. |
| 英文摘要 |
| Nine heavy metals (Cd, Co, Ni, Cu, Zn, Pb, Cs, As, Cr) of surface sediments collected from the Middle Part of the Yarlung Zangbo River were analyzed by BCR sequential extraction procedure. Based on speciation distributions of these metals, ecological risk of heavy metals was assessed with methods of risk assessment code (RAC) and sediment quality guideline quotient (SQG-Q). The results show that: ① Large part of Cr and As belong to residual fraction(87%-96%). Ni, Cu, Co and Cs have similar distribution characteristics(non-residual part accounts for approximate 20%). Correspondingly, mass fraction of Cd exists mainly in acid soluble and reducible faction (65%), indicating high ecological risk level. ② Based on calculation of RAC method, Cd is of high risk to the environment (37.38%). Accordingly, Co, Ni, Cu and Zn are of low risk, and Pb, Cs, As and Cr pose extreme low risk to the environment. According to evaluation of heavy metal speciation distributions, the potential ecological risk of heavy metals is in the descending order of Cd>Co>Ni>Cu>Zn>Pb>Cs>As>Cr. ③ The SQG index of sediments is 0.804, indicating that studied river sediment has a moderate potential biological toxicity effect. Given most of heavy metals exists in residual fraction, the sediments of this region pose a low ecological risk to the environment. |
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