葫芦岛锌厂周围土壤砷污染空间格局和风险评价

Spatial Pattern and Risk Assessment of Soil Arsenic Around Huludao Zinc Plant

采用现场采样及室内分析方法,研究了葫芦岛市锌厂周围67个地点88个土壤样品的砷含量,用Kriging插值模拟了其空间分布特征和污染指数分布,比较了海拔高度不同距锌厂距离相同的不同方向地点的砷含量差异,分析了不同深度砷的分布特点,用单项污染指数法对其进行了环境评价。结果表明,葫芦岛锌厂周围土壤砷的含量范围7.25～492.61mg·kg-1,其空间分布沿西偏北、西南、南方向向外围延伸,最大污染半径达6.4km,距锌厂相同距离海拔度高的地点砷含量高,土壤砷主要富集于表层0～10cm范围内,砷的垂直迁移性差,环境评价结果表明锌厂周围存在砷污染风险。

Heavy metal smelting is regarded as one of the most important anthropogenic metal emission sources. Heavy metal accumulated to a toxic concentration level in environment will lead to ecological damages. Huludao zinc plant, founded in 1937, is the largest zinc producer in Asia. Previous investigations indicated that the soil around Huludao zinc plant had been polluted seriously by heavy metals, such as Hg, Cd, Cu, Zn. However, few reports on arsenic contamination in soil had been found. 88 soil samples from 67 different sites were collected. The spatial distribution pattern of arsenic in soils around Huludao zinc plant was investigated in this paper. The results showed that the highest arsenic concentration was at the 0-10 cm surface soil, and it was difficult for arsenic to transfer from surface soil to deep soil. Arsenic concentrations in surface soil ranged from 7.25 to 492.61 mg·kg^-1, with the average 64.77 mg·kg^-1. The spatial pattern of soil arsenic extended to the western, southern and southwestern directions of Huludao zinc plant, with the maximum radius of 6.4 km. Arsenic concentration decreased with the distance to the zinc plant due to the prevalent wind and topography. Moreover, arsenic concentration increased with altitude at the same distance to the zinc plant. Potential ecological risk was estimated based on the single contamination index method.