广西会仙湿地土壤重金属分布特征及风险评估

目的]调查广西会仙湿地土壤环境质量。方法]]研究广西会仙湿地表层土壤中Cu、Zn、Pb、Ni、Cr、As和Hg 7种重金属元素在不同土地利用类型中的分布特征,并进行风险评估。结果]会仙湿地土壤Zn、Pb、Ni、Cr、Cu、Hg和As 7种重金属的平均含量分别为(141.25±126.62)、(46.99±20.14)、(39.60±13.93)、(110.71±30.84)、(38.76±27.51)、(0.18±0.16)、(17.32±6.92)mg/kg,除As和Hg外,其他重金属含量均超过广西土壤背景值;重金属在不同土地利用类型中存在差异,含量高的地方相对集中于池塘和沟渠,其中河流湿地Hg含量超过国家土壤质量二级标准;Zn与Ni、Cr、Cu、As呈极显著相关(P0.01),而Pb仅与Cr呈极显著相关(P0.01),而与其他重金属元素间均未表现出相关性;不同土地利用类型土壤存在不同程度的重金属污染,河流湿地、林地、沼泽湿地属于中度污染,其他湿地类型为轻度污染。结论]会仙湿地土壤重金属污染已经对生态系统的健康发展构成了一定程度的威胁。

Distribution Characteristics and Risk Assessment of Heavy Metals in Huixian Wetland of Guangxi Province

Objective]The aim was to survey the soil environmental quality of Huixian wetland of Guangxi.Method] The contents, distribution characteristics and potential ecological risk of heavy metals(Cu, Zn, Pb, Ni, Cr, As, Hg)were investigated in different land use types (depth 0-20 cm) in Huixian Wetland of Guangxi Province. Result] The average concentrations of Zn, Pb, Ni, C, Cu, Hg and As in soils were (141.25 ±126.62), (46.99 ±20.14), (39.60 ±13.93), (110.71 ±30.84), (38.76 ±27.51), (0.18 ±0.16) and (17.32 ± 6.92) mg/kg, respectively.The metals of Zn, Pb, Ni, Cr, Cu had high accumulation in soils by comparing to the background concentrations of soil elements in Guangxi Province.The contents of heavy metals varied in different land use types.For example, the woodland, pond, ditch in Huixian Wetland had relatively high content of metals;and the content of Hg in the river exceeded the second grade standard values of Chinese environmental quality standards for soils.Zn had significant positive correlation with the heavy metals Ni, Cr, Cu, As(P<0.01), while the metal of Pb showed extremely significant correlation with Cr (P<0.01), but had no significant relationship with other heavy metals.The soils with different land use types were polluted by heavy metals, and soil from the river wetland, woodland and marsh were moderately polluted, the others were slightly polluted. Conclusion] The healthy development of ecosystem has been threatened by soil heavy metal pollution in Huixian.