Zhuo Hai-Hua, Sun Zhi-Wei, Tan Ling-Zhi, Wu Yun-Li, Lan Jing
Yangtze Valley Water Environment Monitoring Center, Wuhan 430010, China.
School of Resource and Environmental Sciences, Wuhan University, Wuhan 430079, China.
Huan Jing Ke Xue. 2016 Dec 8;37(12):4633-4643. doi: 10.13227/j.hjkx.201605001.
With the construction progress of the Three Gorges Project, the hydrological situation of Three Gorges Reservoir changes greatly, which causes the changes of suspended solids precipitation conditions and surface sediment traits. This research analyzed the temporal and spatial variation of the heavy metal pollution in the surface sediment and the potential ecological risk trends during the years from 2000 to 2015 in the trunk stream of the Yangtze River from Jiangjin to the Three Gorges Dam area and some major tributaries, such as Jialing River, Yulin River, Wujiang River, Xiaojiang River, Xiangxi River. The results showed that the average content ranges of heavy metals (including Cu, Pb, Mn, As, Hg etc.) in surface sediments at the main stream monitoring sections during the study period were 46.5-85.7 mg·kg(Cu), 43.8-65.1 mg·kg(Pb), 784.2-910.6 mg·kg(Mn), 8.44-11.91 mg·kg(As), 0.193-0.236 mg·kg(Hg) respectively; The average content ranges of the heavy metals in surface sediments at the main stream monitoring sections during the study period were 16.5-85.6 mg·kg(Cu), 25.8-74.8 mg·kg(Pb), 573.7-996.3 mg·kg (Mn), 6.96-13.31 mg·kg (As), 0.160-0.232 mg·kg (Hg) respectively. The results also showed that there were obvious differences of the heavy metals content in some areas between the left and right bank of the trunk stream of the Yangtze River in the Three Gorges Reservoir area. The results also showed that the concentration variation trends of the heavy metals were different in the surface sediments, such as Cu, Pb, Mn, As and Hg. The content of Hg was the most influenced element by the water period effect. The concentration variation trends of these elements were different at different monitoring sections during the construction and water harvesting progress of the Three Gorges project. The contents of Cu, Pb, Mn and As in sediment from the Three Gorges Reservoir area showed strong positive correlations between each other. But there was a low correlation between the content of As and those of other elements. There was no significant correlation between the content of Hg and those of other heavy metal elements. According to the geoaccumulation index analytical method, the contents of the heavy metals in surface sediments in the Three Gorges Reservoir area were generally at low enrichment level. But the pollution caused by Hg should be paid attention. The change of potential ecological risk index was small in the main stream and the major tributaries of the Yangtze River (except Wujiang River) in most of the time. It should also be noted that the change of potential ecological risk index fluctuated obviously at a high level before the year of 2008, and then the change fluctuations trends descended with time and tended to be stable.
随着三峡工程的建设推进，三峡水库的水文情势发生了很大变化，这导致了悬浮固体沉降条件和表层沉积物特征的改变。本研究分析了2000年至2015年长江干流江津至三峡坝区以及嘉陵江、御临河、乌江、小江、香溪河等一些主要支流表层沉积物中重金属污染的时空变化及潜在生态风险趋势。结果表明，研究期间干流监测断面表层沉积物中重金属（包括铜、铅、锰、砷、汞等）的平均含量范围分别为46.5 - 85.7mg·kg（铜）、43.8 - 65.1mg·kg（铅）、784.2 - 910.6mg·kg（锰）、8.44 - 11.91mg·kg（砷）、0.193 - 0.236mg·kg（汞）；研究期间干流监测断面表层沉积物中重金属的平均含量范围分别为16.5 - 85.6mg·kg（铜）、25.8 - 74.8mg·kg（铅）、573.7 - 996.3mg·kg（锰）、6.96 - 13.31mg·kg（砷）、0.160 - 0.232mg·kg（汞）。结果还表明，三峡库区长江干流部分区域左右岸重金属含量存在明显差异。结果还表明，表层沉积物中铜、铅、锰、砷、汞等重金属的浓度变化趋势各异。汞含量受水期效应影响最大。在三峡工程建设和蓄水过程中，不同监测断面这些元素的浓度变化趋势不同。三峡库区沉积物中铜、铅、锰、砷含量之间呈较强正相关。但砷含量与其他元素含量之间相关性较低。汞含量与其他重金属元素含量之间无显著相关性。根据地累积指数分析法，三峡库区表层沉积物中重金属含量总体处于低富集水平。但汞造成的污染应予以关注。长江干流及主要支流（乌江除外）大部分时间潜在生态风险指数变化较小。还应注意的是，2008年前潜在生态风险指数变化波动明显处于高位，之后变化波动趋势随时间下降并趋于稳定。
