Fang Zhi-Qing, Wang Yong-Min, Wang Xun, Xie De-Ti, Wang Ding-Yong
College of Resources and Environment, Southwest University, Chongqing 400715, China.
College of Ecological Environmental Engineering, Guizhou Minzu University, Guiyang 550025, China.
Huan Jing Ke Xue. 2020 Mar 8;41(3):1338-1345. doi: 10.13227/j.hjkx.201909208.
Sediment column and soil samples collected from 12 sampling sites in four regions of the Ruxi River, a typical tributary of the Three Gorges Reservoir, were analyzed for eight selected heavy metals including Cr, Ni, Cu, Mn, Zn, Cd, Pb, and Hg to evaluate their spatial and vertical distribution, source, and biological toxic effects. The results showed that the average concentrations of heavy metals were (79.60±11.87), (41.340±4.999), (32.69±8.70), (823.34±125.76), (122.11±22.82), (0.393±0.140), and (29.122±6.811) mg·kg for Cr, Ni, Cu, Mn, Zn, Cd, and Pb, respectively, and (74.84±39.50) μg·kg for Hg, all of which exceeded the sediment background values of the Yangtze River. A spatial trend of decreasing metal concentrations was observed from the reach influenced by the human activities of Ruxi town to the backwater zone and then to the natural river reach. Moreover, in the backwater zone, the heavy metals in sediments and soil along the river were significantly lower than those in sediments, indicating that the sediments and soil were not one primary source for these metals in backwater zone sediment. From the vertical distribution of sediment, in addition to Pb, the highest level of metals was observed at 8 cm in the reach influenced by human activities, and their concentrations decreased with sediment depth in the backwater zone and natural river beach. Significant correlation was found between all the heavy metals (<0.01, except Ni), indicating a potential homology of these metals in the Ruxi River. Evaluation results of the geoaccumulation index reveal that there exists light to partial moderate Cd and Zn pollution in the Ruxi River. The evaluation of biotoxicity effects showed that Ni was likely to have toxic effects on organisms with a probability of 10% to 75%, and Cd, Zn, Hg, Cu, Pb, and Cr are likely to have biotoxic effects at<10% probability. The combined effect values of multiple metals indicated that the risk of adverse effects was between low and lower medium in the sediments of the Ruxi River.
采集了三峡水库典型支流汝溪河四个区域12个采样点的沉积物柱和土壤样本，分析了其中铬（Cr）、镍（Ni）、铜（Cu）、锰（Mn）、锌（Zn）、镉（Cd）、铅（Pb）和汞（Hg）这8种选定重金属的含量，以评估它们的空间和垂直分布、来源及生物毒性效应。结果表明，重金属的平均含量分别为：铬79.60±11.87毫克·千克、镍41.340±4.999毫克·千克、铜32.69±8.70毫克·千克、锰823.34±125.76毫克·千克、锌122.11±22.82毫克·千克、镉0.393±0.140毫克·千克、铅29.122±6.811毫克·千克，汞74.84±39.50微克·千克，均超过长江沉积物背景值。从受汝溪镇人类活动影响的河段到回水区再到天然河段，观察到金属浓度呈下降的空间趋势。此外，在回水区，沿河岸沉积物和土壤中的重金属含量明显低于沉积物中的含量，这表明沉积物和土壤并非回水区沉积物中这些金属的主要来源。从沉积物的垂直分布来看，除铅外，在受人类活动影响的河段8厘米深处金属含量最高，在回水区和天然河滩处，其含量随沉积物深度增加而降低。所有重金属之间均存在显著相关性（除镍外，P<0.01），表明汝溪河中这些金属具有潜在同源性。地累积指数评价结果表明，汝溪河存在轻度至部分中度镉和锌污染。生物毒性效应评价表明，镍对生物体产生毒性效应的概率为10%至75%，镉、锌、汞、铜、铅和铬产生生物毒性效应的概率<10%。多种金属的综合效应值表明，汝溪河沉积物中产生不利影响的风险处于低至较低中等水平。
