三峡库区表层沉积物重金属含量时空变化特征及潜在生态风险变化趋势研究

发布时间：2018-11-11 14:33

【摘要】：三峡工程建设以来,三峡水库干支流水文形势已发生了重大变化,造成水体悬浮物沉降条件改变,可能导致库区表层沉积物性状发生变化.通过对2000~2015年三峡水库干流江津至坝址段和嘉陵江、御临河、乌江、小江、大宁河、香溪河等主要支流表层沉积物中重金属污染物含量水平、时空变化及潜在生态风险变化趋势分析,结果表明,三峡库区在2000~2015年长江干流沉积物中铜、铅、锰、砷、汞元素各断面含量平均值区间分别为46.5~85.7、43.8~65.1、784.2~910.6、8.44~11.91、0.193~0.236 mg·kg~(-1);支流沉积物中铜、铅、锰、砷、汞元素含量平均值区间分别为16.5~85.6、25.8~74.8、573.7~996.3、6.96~13.31、0.160~0.232 mg·kg~(-1).三峡水库干流局部河段左右岸表层沉积物中重金属含量存在较明显差异;铜、铅、锰、砷、汞元素在表层沉积物中含量变化趋势各异,不同水期干支流表层沉积物中重金属含量存在一定程度波动,其中汞元素变化最为明显.不同元素在不同断面随时间变化趋势不完全一致.库区沉积物中铜、铅、锰、砷等元素含量呈现显著的正相关,但砷与其他元素相关性低;汞元素与其他重金属之间无明显相关性.地累积指数法评价表明,三峡库区表层沉积物重金属总体处于较低富集水平,但汞元素污染值得注意;长江干流及除乌江外主要支流大部分时段表层沉积物重金属潜在生态风险指数变化较小,只在部分时段出现升高的情形;乌江表层沉积物重金属潜在生态风险指数2008年前处于相对较高水平,但2008年后下降并趋于稳定.
[Abstract]:Since the construction of the three Gorges Project, the hydrological situation of the trunk and tributaries of the three Gorges Reservoir has changed significantly, resulting in the change of the settling conditions of the suspended matter in the water body, which may lead to the change of the characteristics of the surface sediment in the reservoir area. From 2000 to 2015, the contents of heavy metal pollutants in the surface sediments of the main tributaries of the three Gorges Reservoir from Jiang Jin to the dam site and the Jialing River, the Yulin River, the Wujiang River, the Xiaojiang River, the Daning River, the Xiangxi River, etc., were analyzed. Temporal and spatial changes and potential ecological risk trends are analyzed. The results show that copper, lead, manganese and arsenic in the sediments of the Yangtze River main stream in the three Gorges Reservoir area from 2000 to 2015, The average range of mercury content in each section is 46.5 ~ 85.7 ~ 43.8U ~ 65.1784.2U ~ 910.6 ~ 8.44 ~ 11.91 ~ 0.1993 ~ 0.236 mg kg~ (-1); The average values of Cu, Pb, mn, as and Hg in tributaries are 16.5U 85.6U 25.8U 74.8573.7U 6.966.96 ~ 13.31 ~ 0.160 ~ 0.232 mg kg~ (-1), respectively. There are obvious differences in heavy metals content in the surface sediments of the left and right bank of the local section of the main stream of the three Gorges Reservoir. The contents of Cu, Pb, mn, as and Hg in surface sediments vary in different trends, and the contents of heavy metals in surface sediments of tributaries in different water periods fluctuate to a certain extent, among which the change of mercury is the most obvious. The variation trend of different elements in different sections with time is not completely consistent. The contents of Cu, Pb, mn, as in sediments of the reservoir area showed significant positive correlation, but the correlation between arsenic and other elements was low, but there was no significant correlation between mercury and other heavy metals. The results of geoaccumulation index method show that heavy metals in surface sediments of the three Gorges reservoir area are generally at a low enrichment level, but mercury pollution is worthy of attention. The potential ecological risk index of heavy metals in the surface sediments of the Yangtze River main stream and the main tributaries except the Wujiang River in most periods is relatively small and only increases in some periods. The potential ecological risk index of heavy metals in surface sediments of Wujiang River was relatively high before 2008, but decreased and stabilized after 2008.
【作者单位】：长江流域水环境监测中心;武汉大学资源与环境科学学院;
【基金】：国务院三峡工程建设委员会办公室三峡水库运行维护管理资金项目(JJ2015-008) 水资源高效开发利用重点专项(2016YFC0402207)
【分类号】：X524

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