某典型污染地块土壤砷垂向分布及评价

Vertical distribution and evaluation of soil arsenic in typically polluted plot

使用直推式钻机在面积约73 484 m^(2)污染地块内采集深度0-6 m土壤原状样品225件,垂向采样间距为0.5-1 m。土壤砷含量范围为1.13-1 004 mg·kg^(-1),平均值为78.5 mg·kg^(-1)。采用ArcGIS、数理统计法对不同深度土壤中砷含量进行分析,结果表明:土壤砷含量自上而下呈下降趋势,0-2 m人工填土中的砷明显偏高,最大值位于1 m处,3-6 m原状土中的砷显著降低;样品砷总超标率为20.9%,0-6 m超标率分别为51.92%、30%、14.81%、6.67%、10.53%、0、4.76%,超标率自上而下呈下降趋势。运用地累积指数法评价土壤污染状况,0-1 m为中强污染,2 m为中污染,3 m为轻微污染,4-6 m为无污染。

Direct push drill was used to collect 225 soil samples with a depth of 0-6 m in a contaminated plot with an area of 73484 m^(2),and the vertical sampling interval was 0.5-1 m.Soil arsenic content ranged from 1.13 mg·kg^(-1) to 1004 mg·kg^(-1),with an average of 78.5 mg·kg^(-1).ArcGIS and mathematical statistics were used to analyze the arsenic content in soil at different depths.The results show that the arsenic content in soil decreased from top to bottom.The arsenic content in 0-2 m artificially filled soil was significantly higher,and the maximum value was 1m,while the arsenic content in 3-6 m undisturbed soil was significantly lower.The total exceedance rate of the arsenic samples was 20.9%,and the exceedance rates at 0-6 m were 51.92%,30%,14.81%,6.67%,10.53%,0,and 4.76%respectively.The exceedance rates showed a downward trend from top to bottom.Soil pollution was evaluated by soil accumulation index method.0-1 m was considered as moderate to heavy pollution,2 m as moder-ate pollution,3 m as light pollution,and 4-6 m as no pollution.