The Research Of The Heavy Metal Pollution Characteristic In Sediments Of Dexing Copper Mine Rainwater Network

In order to analyze the pollution characteristics of sediments in the rainwater pipe?ditch?in Dexing copper mine area,the project team carried out sediment samples on the study area.HNO₃-HClO₄–HF digestion method,Tessier five-step extract method and ICP-MS method were used to analyze the content of heavy metals in sediments.In addition to the comparative analysis of the measured data and the national soil environmental quality standard,the single pollution index method,the Nemero comprehensive pollution index method,the geoaccumulation index method and the potential ecological hazard index method were used to evaluate the pollution risk of heavy metal in the sediments of stormwater pipe.The main results achieved are as follows:?1?In the sediments of the study area,the average content of Cr was 110.81 mg/kg,lower than third grade of national soil quality standard which is 300mg/kg.The mean content of Pb was 44.48 mg/kg,the main form was Fe-Mn bound state.Average content of Zn was 340.94 mg/kg,lower than the third grade of soil quality,but there are few individuals over the grade,are located in the Southern District,the main state of Zn was Fe-Mn bound state.The content of Cu and As were obviously exceeding the national tertiary soil quality standard,in terms of Cu,71%was the organic state while effective state was 9%,as to As,88%was the residue state while 4%was valid state,so the release risk of Cu and As were not high.The concentration of Cd was slightly larger than the standard value?1.06mg/kg?,and its area distribution characteristic was obvious.The Cd concentration in the residential area was significant higher than that in other regions,and the ratio of exchangeable state,carbonate-bound state and Fe-Mn oxidation state in Cd were high,means that Cd has a large risk of release.?2?Four kinds of index evaluation methods,which are widely used at home and abroad,were used to evaluate the risk of heavy metal pollution in the study area.All the results of the evaluation methods reflect the Cr,Zn and Pb pollution index is relatively low,there pollution risk was low or clean while the pollution risk of Cd is much higher,the spatial distribution characteristics of Cd content were obvious:the residents concentrated areas were much lager than other area.All evaluate methods show their differences,mainly as follows:the results of pollution evaluate of Cu and As were quite different,geo-accumulation index shows the pollution risk of Cu and As were relatively small while another 3 methods were on the contary;the overall result of each methods was not totally asame.The main reason for these differences is that each method focuses on different directions,the choice of reference standards also has greater subjectivity.