丹江口水库淅川淹没区土壤中汞和砷的赋存特征及生态风险评价

Distribution Characteristics and the Potential Ecological Risk of Hg and As in the Soil of Xichuan Submerged Area in the Danjiangkou Reservoir,China

为研究丹江口水库淅川淹没区土壤中Hg和As的赋存特征及潜在风险,采集高程在170m以下8个乡镇18个采样点不同利用类型的土壤样品共30个,微波消解后采用氢化物发生原子荧光光谱法测定。结果表明:淅川淹没区土壤中Hg和As的含量均未超过国家规定的土壤环境质量Ⅱ类标准(GB15618—1995),但Hg的变异程度较强,反映了在淹没区各区域土壤中Hg的来源存在较大差异。Hg和As的含量与土壤的理化性质存在一定的相关性:pH与Hg的含量呈极显著负相关,与As呈显著正相关;有机质(TOC)和Hg的含量呈显著正相关,与As呈负相关,但显著性不明显。采用Hakanson潜在生态风险指数法对土壤中Hg和As进行风险评价,综合潜在风险指数表明,研究区Hg和As的总潜在生态风险值较低,生态危害程度为轻微污染。从单元素角度分析,Hg的潜在生态危害程度要高于As,且部分属于中等污染水平,值得进一步关注。

The distribution characteristics and potential ecological risk of Hg and As in the soil of Xichuan submerged area in the Danjiangkou Reservoir were studied.Thirty soil samples were collected and determined using hydride generation-atomic fluorescence spertrometry after microwave digestion.The results showed that the concentrations of Hg and As met grade II of the Environmental Quality Standard for Soil.However the variation of Hg was significant,which indicated different sources of Hg in the soil of Xichuan.The contents of Hg and As were correlated to soil properties.There were significantly negative relationship between pH and Hg,positive relationship between pH and As and positive relationship between organic matter and Hg.The negative relations between organic matter and As was not significant.The potential ecological risks of Hg and As assessed to be low in most areas of the Danjiangkou Reservoir by using the Hakanson ecological risk index method.The single factor analysis indicated a higher ecological risks level for Hg than As for irrigation regions.The moderate pollution level of Hg in some area of Danjiangkou Reservoir calls for further attention.