| 梅江流域清凉山水库沉积物重金属污染、生态风险评价及来源解析 |
| 摘要点击 2830 全文点击 888 投稿时间：2020-03-02 修订日期：2020-06-17 |
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| 中文关键词 沉积物 重金属 生态风险 来源解析 清凉山水库 |
| 英文关键词 sediment heavy metals ecological risk source apportionment Qingliangshan Reservoir |
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| 中文摘要 |
| 水库沉积物是重金属等污染物重要的汇，在酸碱及氧化还原条件变化下沉积物存在污染物释放的潜在风险，释放到水环境中的重金属通过食物链的传递，对人类的健康造成威胁.据此，本文以梅江流域清凉山水库为研究对象，围绕沉积物重金属含量水平、形态分级、污染和潜在生态风险评价及污染溯源展开调查.结果发现，库区沉积物中重金属含量大小依次为溪田支流 > 坝前及库中心 > 新田-白水支流.沉积物重金属生物有效态占比差异较大，质量分数依次为：镉（Cd，89%） > 铅（Pb，76%） > 锌（Zn，54%） > 铜（Cu，43%） > 镍（Ni，28%） > 铬（Cr，10%）.采用地累积指数法开展重金属污染评价，采用潜在生态危害指数法开展重金属生态风险评价.地累积指数法显示，水库沉积物重金属元素污染程度依次为：Cd > Pb > Zn > Cu > Cr > Ni；潜在危害生态指数法显示，重金属潜在生态风险程度依次为：Cd > Pb > Cu > Ni > Zn > Cr，水库沉积物Cd的潜在生态风险最大，对生物影响最大.相关性分析和主成分分析结果表明，水库沉积物重金属Cu、Zn、Pb和Cd主要来源于农业施肥的外源污染输入，Ni和Cr主要来源于区域后边林地等背景区土壤水土流失.库区沉积物重金属污染存在显著空间差异性.新田-白水河补给区域污染最轻，与控制流域土地利用主要为林地，污染源较少密切相关.溪田河补给区域污染最重，其控制流域多茶园及农田，外源肥料污染负荷最大.库区坝前及中心重金属污染程度介于两支流补给区之间，表现为明显的混合作用. |
| 英文摘要 |
| Reservoir sediment is an important sink for pollutants such as heavy metals. Under the changes in acid-base and redox conditions, there is a potential risk of heavy metals release into the water environment, which are transmitted through the food chain and threaten human health. Therefore, this study investigates the Qingliangshan Reservoir in the Meijiang River Basin, and conducts research concerning the contents and speciation of heavy metals in the sediments, potential ecological risks, and source apportionment. This study found that the content of heavy metals in the sediments of the reservoir area was in the order:Xitian tributary > dam front and reservoir center > Xintian-Baishui tributary. There is a large difference in the speciation of heavy metals in the sediments. Zn is mainly acid-soluble and in the residual state, Pb is mainly in an Fe/Mn oxide bound state, Cd is mainly in an acid-soluble state, and Cu, Ni, and Cr are in the residual state. Mainly, the percentage of bioavailable states are Cd(89%) > Pb(76%) > Zn(54%) > Cu(43%) > Ni(28%) > Cr(10%). The geoaccumulation index method shows that the pollution degree of heavy metal elements in reservoir sediments is in the order Cd > Pb > Zn > Cu > Cr > Ni, and the potential hazard ecological index method shows that the pollution degree of heavy metals is Cd > Pb > Cu > Ni > Zn > Cr. The potential ecological risk of Cd in the reservoir sediments is the largest, and the biological impact is greatest. Correlation analysis and principal component analysis results show that heavy metals Cu, Zn, Pb, and Cd in reservoir sediments are mainly from agricultural pollution, and Ni and Cr are mainly from natural background. Combined with the analysis of soil heavy metal content in the watershed, heavy metal pollution in the Qingliangshan Reservoir sediments originates from the effect of rainfall runoff and the use of agricultural chemical fertilizers before flooding in the upstream of the reservoir tributaries. There are significant spatial differences in heavy metal pollution in the sediments of the reservoir area. The Xintian-Baishui River recharge area is the least polluted, and it is closely related to the land use in the controlled watershed, which is mainly forest land, with fewer sources of pollution. The Xitian River replenishment area has the heaviest pollution. It controls many tea gardens and farmlands in the watershed, and the load of external fertilizer pollution is the largest. The pollution degree of heavy metals in front of the dam and the center of the reservoir area is between the two tributary replenishment areas, showing an obvious mixing effect. |
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