有色冶金区土壤-玉米系统汞累积及健康风险

Accumulation of Mercury in Soil-maize System of Non-ferrous Metals Smelting Area and Its Related Risk Assessment

有色冶金区土壤重金属污染,尤其是汞污染一直受到广泛关注.为了了解葫芦岛市稻池村玉米地汞在土壤-玉米农田系统中的迁移转化,以葫芦岛市稻池村为研究对象,对该区域玉米地土壤Hg含量、分布特征、污染现状及玉米植株各器官Hg含量进行分析.玉米地土壤Hg含量范围为0.25~3.49 mg·kg-1,平均值1.78 mg·kg-1,是辽宁省土壤环境背景值的48倍.在锌厂周围2~3 km范围内,以锌厂为中心,随着距离的增大土壤Hg含量逐渐增加.地累积指数法评价结果表明,研究区玉米地土壤Hg污染均在中等污染以上,其中,属于严重污染的土壤样品占总样品的54.6%.运用Hakanson潜在生态危害指数法对玉米地土壤Hg潜在生态风险进行评价.潜在生态风险为极强的占72.7%.运用目标危险系数法(THQ)对暴露人体进行健康风险评价,结果表明,虽然土壤中富含汞,但是由于汞较难在土壤-玉米系统中迁移,因此籽粒中的汞富集并不高,食用玉米对人群没有明显的健康风险,但是儿童遭遇Hg健康风险要远高于成人,危险指数达到0.056.

Soil heavy metal pollution,especially the mercury pollution,has been widespread concern in non-ferrous metallurgical area.This study focused on the content,distribution and pollution status of Hg in maize soil of Huludao city. Meanwhile,Hg contents in the various organs of maize were analyzed. Hg concentration in soil ranged from 0. 25 to 3. 49 mg·kg- 1with the average content of 1. 78mg·kg- 1,which was 48 times as high as the background value of Liaoning soil. Around 2-3km range of zinc plant,the pattern of spatial distribution showed that the content of Hg was gradually increased with the increase of the distance to Huludao zinc plant. The result of geoaccumulation index reflected that Hg pollution is up to moderate pollution level on the whole. 54. 6% of the total sample were belonged to the serious pollution level. The potential ecological risk index of Hakanson was applied to assess the ecological risk of Hg. The target hazard quotient method( THQ) was used to assess the health risk for human,the results revealed that there was no significant health risk by consumption corn. Mercury is very difficult to transport in soil-maize system,and there is no obvious health risks to adults. But the risk coefficient of children,which is up to 0. 056,is much higher than adults.