重庆市江津区中小河流底泥重金属调查与生态评价

Investigation and ecological evaluation of heavy metals in sediment of middle and small rivers in Jiangjin District,Chongqing City

随着人类活动的影响,重金属污染程度一直在增加,大多数重金属都储存在河流沉积物中。为研究重庆市中小河流底泥重金属污染情况,2020年6月,以江津区流域面积大于50 km^(2)的李市小溪、石板溪、綦江、笋溪河、壁南河、桥溪河、大溪河、安家溪等8条河流,以及山区的卫星水库,作为研究对象,共布设22个监测点位,对其底泥Cd,Cr,Cu,Pb,Zn和As等6种重金属进行本底调查,通过地累积指数法、潜在生态风险评价指数法对其重金属污染进行综合评估。结果表明:江津区中小河流底泥重金属整体污染状态不高,依据I_(geo)评价,Cd达到中度污染水平,其余元素处于低污染或者无污染水平;潜在生态风险评价,大部分处于中度风险状态,Cd对RI的贡献率最大(平均贡献率为93.05%),需要作为重点监控对象;通过主成分分析和聚类分析,表明Cr,Cu,Zn,Cd,Pb元素可能具有相同的来源,且重金属污染主要发生在工业为主导的区域(S17,德感工业园区)、人口集中的城市区域(S18,双福街道)和污水管网不全的农业污染区域(S4,李市小溪;S22,卫星水库)。

Heavy metal pollution is becoming increasingly serious as a result of human activities,and most heavy metals are stored inriversediments.To study the heavy metal pollution in the sediment of small and medium-sized rivers,in June 2020,eight rivers with drainage area greater than 50 km^(2),with Lishixiaoxi River,Shiban River,Qijiang River,Sunxi River,Bi nan River,Qiaoxi River,Daxi River,An jiaxi River,and the Weixing Reservoir in the mountains and 22 of sensors monitoring points.The Cd,Cr,Cu,Pb,Zn,and As,six kinds of heavy metal sediment was studied as the research object.The heavy metal pollution was comprehensively assessed by the method of land accumulation index and heavy metal potential ecological risk assessment index.The results showed that the pollution status of heavy metals in the sediment was not high.According to I_(geo) evaluation,Cd reached the moderate pollution level,and other elements were at the low or no pollution level.According to the assessment of potential ecological risks,most of the areas were at moderate risk,and Cd had the largest contribution rate to RI(average contribution rate was 93.05%),which should be taken as the key monitoring object.Principal component analysis and cluster analysis showed that Cr,Cu,Zn,Cd,and Pb elements may have the same source,and heavy metal pollution mainly occurred in the industrial-dominated area(S17,Degang Industrial Park)or the urban area with concentrated population(S18,Shuangfu Street).Agricultural polluted areas with incomplete sewage network(S4,Lishixiaoxi River;S22,the Weixing Reservoir).