| In recent years, the soil heavy metal pollution has attracted universal attention. In this paper, the soil around one waste incineration plant in Chongqing was taken as the research object, 10 surface soil samples in the study area were collected in 2013. In this study, multivariate statistical and spatial analysis were used to discuss the soil physical and chemical properties, the annual statistical characteristics of the content of heavy metals, spatial distribution, interannual variation, pollution sources, the degree of pollution, and the evaluation of ecological risk and health risks of soil heavy metal pollution. The results showed:① The p H of the surface soil around the waste incineration plants was in the range of 4.23-7.37, the average value was 5.78, which indicated that the study area was acidic soil; The range of organic matter content in the soil was 0.96%~7.01%, the average value was 4.38%. The range of cation exchange capacity in the soil was 24.84~34.44 cmol/kg, with an average of 30.35 cmol/kg.② Four kinds of heavy metals in surface soil around the waste incineration plants presented the trend of accumulation with time changed, in addition to Cr, Pb, Zn, Cu disturbed by external factors more than 2012.③ Pb, Zn were significantly correlated with p H, Cr and p H showed a moderate correlation,while the correlation of Cu with p H was relatively low, cation exchange capacity with four heavy metals did not show significantly correlation. Pb, Zn, Cr were significantly correlated with the content of organic matter, while the correlation of Cu with the content of organic matter was relatively low. Pb, Zn, Cr presented significantly correlation with each other, while the correlation of Pb, Zn, Cr with Cu were relatively low.④ According to the results of the analysis of spatial analysis and interannual change, flue gas emission by the waste incineration plant was a major source of Pb, Zn in the soil, Cr in the soil not only comed from the incineration plant flue gas emissions, but also comed from the legacy pollution in region of chromate production factory before, and Cu was mainly from agricultural activities.⑤ Single factor pollution index evaluation results showed that: when second grade standardized value as critical value, the concentrations of Pb, Zn, Cu in all the samples were to reach the standard, Cr in 8# samples presented light pollution; when Chongqing background values as critical value, in addition to the concentrations of Zn in 3#,4#,6#,10# samples and Cr in 4# were not exceeded, four metals in remaining samples were exceeded, Pb pollution levels presented severe pollution, Cr pollution levels presented moderate pollution, Zn, Cu presented light pollution. Nemerow pollution index evaluation results showed that: when second grade standardized value as critical value, the extent of soil contamination in the study area was in the vicinity of cordon; when Chongqing background values as critical value, the extent of soil contamination in the study area presented severe compound pollution, and Pb, Cr made larger contribution to the contamination. The potential ecological risk assessment study results showed that: when second grade standardized value as critical value, ecological risk factors of four heavy metals were small, the degree of potential ecological risk of four heavy metals in the study area belonged to mild comtamination; when Chongqing background values as critical value, ecological risk factor of Pb was heavier, ecological risk factors of Cr, Cu were moderate, while the ecological risk factor of Cu was small, the degree of potential ecological risk of four heavy metals in the study area belonged to moderate comtamination⑥ The non- carcinogenic risk indexs of Pb, Zn, Cr, Cu in all the soil samples exposured through oral, skin, respiration for adult were less than 1, the noncarcinogenic risk to adult was acceptable in the study area; The non- carcinogenic risk indexs of Pb, Zn, Cr, Cu in all the soil samples exposured through oral, skin, respiration for children, in addition to 10# sample was less than 1, the rest of the samples were all more than 1, the non- carcinogenic risk to children was unacceptable in the study area. The non- carcinogenic risk contribution rate of the exposure ways followed by oral intake>skin intake>breathing intake not only for adult but also for children, the noncarcinogenic risk contribution rate of different heavy metals followed by Pb>Cr>Zn>Cu.⑦ Based on the situation of the study area and the analysis of the various repair techniques, this study suggested that combined phytore mediation with agricultural measures to achieve the efficient repair with low investment. |
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