Speciation And Pollution Risk Research Of Heavy Metals In Sediment And Riparian Soil Of Huixi River Of Tongling City

This paper took Huixi River of Tongling City as object, collecting sedimentsand riparian soil samples in12representative sampling sites. Based on the sampletest and analysis of Cr, Cd, Cu, Zn, Ni, Pb and As content, the paper analyzed thespecies distribution and migration characteristics of river sediments and heavymetals in riparian, and assessed the contamination extent and pollution risk ofheavy metal. The main research content and results were as follows:(1) By the analysis of the average content and background values of heavymetals in soil of Tongling city, the average content of7kinds of heavy metals insediments were far more than the background values. And the degree of pollutionwas ranked as: As> Cd> Cu> Zn> Pb> Ni> Cr; except Cr and As,5other heavymetals were beyond the background values, also the pollution degree was ranked asAs> Cd> Zn> Cu> Pb> Ni> Cr.(2) According to the index of geoaccumulation, the pollution degree of heavymetals in sediment was As> Cu> Cd> Ni> Zn> Pb> Cr, In the whole rivergeo-accumulation index of sediment showed the high trend on the upper anddownstream, and low trend in the midstream; the pollution degree of heavy metalsin bank soil varied greatly, with the total performance of As> Cd> Ni> Cu> Zn>Pb> Cr, and the pollution degree of2#sampling point was the lightest, meanwhile11#sampling point was the highest. According to Nemero pollution index, theheavy metals content of all sampling points were more than heavy pollutionthreshold. Sorting pollution level was12#>4#>3#>6#>2#>11#>1#>7#>10#>5#>9#>8; the pollution degree of each sampling point in riparian soils was4#>11#>1#>6#>7#>5#>9#>10#>8#>3#>12#>2#.(3) The speciation of Cd in sediments and riparian soil samples was mainlyFe-Mn oxide bound, the speciation of Cu was mainly the organic and sulfide bound,and the form of other5elements was mainly the residual state.(4) The order of migration ability of heavy metals in the sediment was: Cd> Ni> Cr> Zn> Cu> As> Pb, and the order in the coastal zone of soil was: Cd> Ni>Zn> Cu> As> Pb=Cr. Although7kinds of heavy metals had reached moderate orhigher pollution level, the migration ability was also weak because the mainlyspeciation was the residue state,.(5) The SQG-Q coefficients of heavy metals in all sediment samples were greater than1, showing that the Hui River had been polluted by heavy metalsseriously, and the potential adverse biological effects was very high; the SQG-Gcoefficient of most points in riparian soil was greater than1, and the potentialadverse biological toxicity effect was relatively high.(6)According to the risk assessment code method, the sorting of ecological riskof heavy metal pollution in ediment was: Cd> Ni> Cr> Zn> Cu> Pb> As.Exceptthe1#and8#with the medium ecological risk level, the remaining points were in ahigh ecological risk. The order of ecological risk of contamination in riparian wasCd> Ni> Pb> Zn> Cu> As> Cr. Except1#,4#and5#sampling points with thesecondary pollution risk, the other points were high ecological risk ofcontamination or above level.