独山锑冶炼厂周边土壤锑砷空间分布特征、污染评价及健康风险评估

Spatial distribution characteristics, contamination evaluation and health risk assessment of arsenic and antimony in soil around an antimony smelter of Dushan County

以贵州省独山县某锑矿冶炼厂周边土壤为研究对象,按照辐射布点取样的原则,布设45个采样点,共采集0~30 cm的土壤样品135件.基于GIS空间分析、内梅罗指数及人群健康风险评价等研究方法,分析了地形和风向对锑(Sb)在土壤中分布的影响,并对Sb和As在该区域土壤中的含量、空间分布、污染水平及人体健康风险进行了探究与评估.结果表明,Sb在新、老两厂周边不同深度(0~10、10~20、20~30 cm)土壤中的含量平均值分别是贵州省背景值的11.90、9.24、4.32和8.13、8.06、4.88倍,且随深度增加呈明显降低的垂直分布特征,其在20~30 cm深度土壤中的含量接近贵州省土壤背景值.而As在不同深度土壤中的含量变化不明显,总体平均值在贵州省土壤背景值的1.39~1.62倍之间.老冶炼厂周边土壤中Sb有效态含量占比均高于新厂区,且随土壤深度的增加而增加,而As在各层位土壤中均以残渣态为主,其含量占比高达80%以上.Sb在新、老冶炼厂周边土壤中的分布受到地形和主导风向影响,在烟囱周边300 m范围内土壤中Sb含量最高,随距离增加呈现缓慢降低特征;同时,土壤中Sb含量随海拔的增加而降低.从土壤污染的空间分布上看,老冶炼厂东北面土壤尚属清洁,其余区域达到轻微污染水平.人体健康风险评价结果显示,冶炼厂周边土壤中As的致癌风险不明显,As和Sb对成人与儿童的非致癌健康风险均较小.

In the present study, taking the surrounding soil of a antimony smelter in Dushan County of Guizhou Province as the study object, 45 sampling points were set up to collect 0~30 cm soil(135 samples in total) according to the principle of radiation distribution sampling. And the GIS technique, Nemerow comprehensive index method and USEPA health risk assessment model were conducted to study the influence of terrain and wind direction on the distribution of soil Antimony(Sb). In addition, Arsenic(As) and Sb contents, spatial distribution, soil pollution and human health risks of these samples were investigated and evaluated in the area. The results showed that, compared to the background values of Guizhou Province, the average values of Sb contents were 11.9, 9.24, 4.32, 8.13, 8.06 and 4.88 times, respectively, in the soil around the new and old plants at different depths(0~0, 10~20, 20~30 cm), which decreased significantly with the increase of depth, and approaches the background value at the layer 20~30 cm. Moreover, the content of As in soils at different depths did not change significantly, and the overall average value was between 1.39 and 1.62 times to the soil background value. The proportion of available fraction of Sb around the old factory increased with the increase of soil depth, which was higher than that of the new factory. However, As was main part in the residual fraction at each layer, up to more than 80%. The distribution of Sb in soil is affected by topography and dominant wind direction. The content of Sb in the soil is the highest within 300 m away from the chimneys, which decreases steadily with the increase of distance. Meanwhile, the content of Sb in the soil decreases with the increase of altitude. According to the spatial distribution map of soil pollution, the soil in the northeast of the old factory is still clean, and the other areas have reached the level of slight pollution. In terms of human health risks, the non-carcinogenic health risks of adults and children are generally small, while the carcinogenic risks of As are not obvious.