城市湖泊底泥污染分析及生态风险评价——以沅江市中心城区为例

Pollution analysis and ecological risk assessment of urban lake sediments—Taking Yuanjiang Downtown as an example

近年来,随着经济的快速发展和城市化进程的加快,城区污水排放量增加,城市湖泊底泥污染问题变得十分突出。采用营养盐有机指数法、重金属内梅罗指数法和潜在生态风险指数法,分析沅江市中心城区湖泊底泥的污染状况和风险水平,以期为城市湖泊底泥污染治理和水环境系统的可持续发展提供科学依据。结果显示:各湖泊底泥污染风险水平受人类活动和工业企业污染影响的程度由大到小排序为X湖>S湖>L湖>H湖;H湖底泥营养盐和重金属整体处于尚清洁水平;L湖L1#、L7#、L8#点位浮泥层底泥存在不同程度营养盐或重金属超标情况,L1#过渡层底泥重金属潜在生态风险指数达到了中等风险水平;S湖S7#、S12#点位浮泥层底泥重金属潜在生态风险指数达到了中等及以上污染风险水平,S3#点位浮泥层底泥重金属潜在生态风险指数达到了强风险水平;X湖X3#、X4#点位浮泥层底泥重金属内梅罗指数最高达到了重度污染水平,与潜在生态风险指数的极强风险水平相吻合,建议进一步核实后结合实际情况对污染湖泊开展内源污染治理工作。

With the rapid development of economy and the acceleration of urbanization process in recent years,and the increase of urban sewage discharge,the problem of urban lake sediment pollution has become increasingly prominent.Nutrient organic index method,heavy metal Nemero index method and potential ecological risk index method were used to analyze the pollution status and risk grade of lakes sediment in the central urban area of Yuanjiang,in order to provide scientific basis for the control of urban lakes sediment pollution and sustainable development of water environment system.The results show that,the order of the risk grade of sediment pollution of each lake affected by human activities and industrial enterprises was X Lake>S Lake>L Lake>H Lake;The nutrients and heavy metals in the sediment of Lake H at a relatively clean level as a whole;The sediment of the floating mud layer at L1#,L7#and L8#points of L Lake has exceeded the standard of nutrients or heavy metals to varying degrees,and the potential ecological risk index of heavy metals in the sediment of L1#transition layer has reached the medium risk grade;The potential ecological risk index of heavy metals in the sediment of the floating mud layer at S7#and S12#of S Lake has reached the level of medium or above pollution risk,and the potential ecological risk index of heavy metals in the sediment of the floating mud layer at S3#has reached the level of strong risk;The Nemero index of heavy metals in the bottom mud of the floating mud layer at point X3#and X4#of Lake X has reached the highest level of severe pollution,which is consistent with the extremely strong risk grade of the potential ecological risk index.It is recommended to carry out endogenous pollution control work on the polluted lake in combination with the actual situation after further verification.