| This paper selected river sediments in southern JiangSu as research objects, studied the contents of heavy metals and organic pollutant, also analyzed the characteristics of heavy metals and organic contamination pollution in sediments. Furthermore, collected some other related materials, assessed the environmental risk of heavy metals and organic contamination.Following conclusions were achieved:1. The organic contamination had different detected extent, in this paper, 27 kinds of organic pollutants were detected in the sediment samples, including phenols, polycyclic aromatic hydrocarbons, phthalic acid esters, nitryl aromatic hydrocarbons, chloric hydrocarbons, aniline, benzidine and organic phosphor, with the mean contents of total Phthalic acid esters being 2.844 mg/kg (range: 0.038～12.775mg/kg) and mean contents of PAHs being 0.538 mg/kg (range: 0.098～1.959mg/kg), respectively. Compared with other organic pollutants, contents of PAEs and PAHs in sediments were higher, which illustrates that the contamination of PAEs and PAHs was serious in sediment. In addition, the contents of organic pollutants vary with the types of sediments collected from nearby rural residential area, breeding site and farmland, with the order: nearby residential area＞nearby breeding site＞nearby farmland.2. According to the result of risk assessments of organic pollutants, we can see that 5 kinds of organic pollutants' ratio of ECWC to RfD were greater than 1, which had potentially environmental risk. Among these organic pollutants, naphthalene and phthalic acid esters' ratio of ECWC to RfD were not only greater than 1 but also having possible carcinogenic, their ecological risk belong to the third stage, which was the same thing as needing to have risk limits and taking measures to reduce the risk; the ecological risk of the rest organic pollutants were low.3. Through analysics the contents of heavy metals in river sediments of southern JiangSu, the content of Cu, Cd changed bigger, but the content of the Zn, Pb and Cr variety the difference were smaller. The mean contents of Cu was 2.844 mg/kg (range:8.4～98.1mg/kg), the tallest content was 11.67 times as great as the lowest content; and the mean contents of Cd was 0.57mg/kg (range: 0.17～3.56mg/kg), the tallest content was 20.9 times as great as the lowest content; the mean contents of Zn was 121.04mg/kg (range: 52.1～243.2mg/kg), the tallest content was 20.9 times as great as the lowest content; the mean contents of Pb was 38.99mg/kg (range: 15.9～64.lmg/kg), the tallest content was 4.03 times as great as the lowest content; the mean contents of Cr was 86.9mg/kg (range: 41.8～210.5mg/kg), the tallest content was 5.04 times as great as the lowest content.Being distributed a characteristic by the heavy metals in river sediments could see:5 kinds of contents of heavy metals pollutants ordered to present to distribute a characteristic mostly and alikely at the No.6～11 sample, this 6 samples were all collected in residents living area, these of the bottom mire heavy metals content were higher.Opposite also residents area to say, the river sediment heavy metals of farmland neighborhood and farming factory surroundings polluted more lightly.Analyzed to see from the relativity of heavy metals, the relativity of of the heavy metals in the bottom mire had already taken place variety, which was differed from that of in the soil.The relativity which explains the of heavy metals in river sediments was subjected to various influence4. The ecosystem risk index number method of the Hakason and the geology backlog index number number(Igeo) of the Muller of the usage classic of this text's evaluation to heavy metals chemical element carry on an evaluation, and contrast its evaluation result, get to draw a conclusion:The total risk degree of southern JiangSu of river seiments was lower, only sampling to order to had higher risk separately, using the geology backlog index number method to evaluate, the index number Class of the geology backlog of the No. 10 sample point was the tallest, was a VI stage, which was the same thing as pollute seriously;The No.5 sample and the No.9 sample polluted lightly, wasⅤandⅣstage..For river sediments of different type the risk degree of the sample to say that Be presented as follows trend: The residents live area＞farmland surroundings＞farming factory surroundings.
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