锑矿区土壤As和Sb形态分布及生态风险评价

以晴隆锑矿区土壤为研究对象,利用连续提取法对土壤中As、Sb的形态分布和生物可利用性进行了研究,并分别利用单因子指数和生态风险指数评价了研究区土壤中As、Sb污染程度和生态危害风险。结果表明,土壤样品中As尤其Sb含量很高,不同采样点含量差别较大。土壤As、Sb的存在形态均以残渣态为主,其次是可还原态、可氧化态、弱酸提取态,水溶态很低。土壤中生物可利用态砷占0.01%~1.08%,其含量为0.001~0.347mg/kg,而土壤中生物可利用态锑占0.08%~3.26%,其含量为0.002~14.107mg/kg。从单因子污染评价看,研究区土壤Sb污染远大于As污染,且大多属于重度污染。土壤中两种金属的综合污染指数(RI)为14.59~1970.98,锑矿区总体处于轻度生态危害,部分区域Sb污染应引起重视。

Speciation Distribution and Ecological Risk Assessment of Antimony and Arsenic in Soils of the Antimony Mining Area

The contents of As and Sb in soils of the Qinglong antimony mining area were analyzed and the speciation distribution and bioavailability of As and Sb were investigated, and the single factor pollution index and the risk assessment code (RAC) were used to evaluate the pollution status and the potential ecological risk in soil samples, respectively. The results showed that the contents of As and Sb were high and there was a great difference from one sample to another. The speciation of As and Sb in soils follows the distribution order of residual fraction > reducible fraction, oxidisable fraction, mild acido-soluble fraction > water-soluble fraction. The concentrations of easily bioavailable antimony were 0.002-14.107 mg/kg and accounted for 0.08%-3.26% while 0.001-0.347 mg/kg and 0.01%-1.08% with respect to arsenic. Based on the single factor pollution index assessment results, the antimony mining area had a high pollution level, following the order of Sb > As. And the two metals range from 14.59 to 1970.98, indicating that the whole potential ecological risk of the two metals in the antimony mining area was low, and the pollution of the same area should be taken into consideration seriously.