南水北调东线工程沿线湖泊表层沉积物重金属污染特征及生态风险评价

Pollution characteristics and ecological risk assessment of heavy metals in surface sediments of lakes along the east route of South-to-North Water Diversion Project

  • 摘要: 以南水北调东线工程的南四湖、骆马湖、洪泽湖、高邮湖为研究对象,通过优劣解距离多指标综合评价模型(TOPSIS法)和潜在生态风险指数法分析4个湖泊表层沉积物中7种重金属(Cr、Cu、Ni、Zn、Pb、Cd、As)空间分布特征及生态风险,并与我国五大湖区其他湖泊进行对比分析。结果显示:4个湖泊表层沉积物重金属浓度均低于同在东部平原湖区的太湖、巢湖、洞庭湖、鄱阳湖等湖泊,但高于蒙新、青藏、东北山地与平原湖区的湖泊,不同区域湖泊沉积物重金属分布具有明显的差异,除了地质构造特征外,工农业生产等人类活动也是导致湖泊沉积物重金属存在差异的主要因素;TOPSIS法评价结果显示,4个湖泊表层沉积物重金属综合风险存在一定空间差异,可能受沿线陆域土地利用类型变化、工农业生产等人类活动等因素的影响,重金属污染程度排序为南四湖>高邮湖>洪泽湖>骆马湖;4个湖泊表层沉积物重金属综合潜在生态风险水平为低,但Cd单项重金属存在中度至较高潜在生态风险。建议加强南水北调东线工程沿线湖泊周边工农业生产排放的监管,进一步调整和优化各湖泊沿线的产业结构,同时加强重金属特别是Cd等入湖的管控,以确保南水北调东线工程沿线湖泊的水环境安全。

     

    Abstract: Nansi Lake, Luoma Lake, Hongze Lake and Gaoyou Lake along the east route of South-to-North Water Diversion Project were taken as the research objects, the spatial distribution characteristics and ecological risks of seven heavy metals (Cr, Cu, Ni, Zn, Pb, Cd, As) in the surface sediments of the four lakes were analyzed by the multi-index comprehensive evaluation model (TOPSIS method) and the potential ecological risk index method, and were compared and analyzed with other lakes in the five geographic regions of China. The results showed that the concentration of heavy metals in the surface sediments of the four lakes was lower than that of Taihu Lake, Chaohu Lake, Dongting Lake and Poyang Lake in the Eastern Plain Lake Area, but higher than that of the lakes in Mengxin, Qinghai-Tibet, Northeast Mountain and Plain Lake areas, and the distribution of heavy metals in lake sediments in different regions had obvious differences. In addition to geological structural characteristics, human activities such as industrial and agricultural production were the main factors that led to differences in heavy metals in lake sediments. The comprehensive potential ecological risk level of heavy metals in the surface sediments of the four lakes was low, but the individual heavy metal of Cd had moderate to high potential ecological risks. It was recommended to strengthen the supervision of industrial and agricultural production discharge around the lakes along the east route of South-to-North Water Diversion Project, further adjust and optimize the industrial structure along each lake, and strictly control the input of heavy metal pollution, especially the control of heavy metal Cd and other human activities, to ensure the water environment safety of the lakes along the east route of South-to-North Water Diversion Project.

     

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