销毁高危化学品造成土壤污染的解析及评价——以南京某地销毁含砷高危废旧弹药污染水泄漏为例

Analysis and Evaluation of Heavy Metals in Soil Polluted by Water Leakage During High-risk Arsenical Chemicals Destruction —— A Case Study of High-risk Bombs Destruction in Nanjing, China

通过对南京某地销毁含As高危废旧炮弹过程中污染水泄漏事件的调查数据统计分析和分布态势研究,从7种重金属中逐步确定了污染区域的4种主要重金属污染物,并利用污染指数法,采用不同的评价标准对重金属污染进行了评价。结果表明,研究区域的主要污染物为As、Cr、Cu、Hg,As和Cr与污染水泄漏有关,并受周边居民生活活动的影响,Cu、Hg污染来源与事件无关;以背景对照点上限值(St-1)为评价标准,重金属累积性污染综合污染指数为3.57,土壤受到Cu、Hg的严重污染;以《土壤环境质量标准》(GB/T 15612-1995)二级标准(St-2)和《食用农产品产地环境质量评价标准》(HJ 332-2006)指标限值(St-3)为评价标准,土壤重金属综合污染指数为1.58和1.60,该地不适合种植无公害蔬菜或食用等农作物;以中国蔬菜地土壤重金属健康风险基准值(St-4)为标准评价,考虑到重金属被蔬菜吸收的难易性,Cr会造成污染区域的叶类、瓜类等可食用植物存在安全隐患。

Analysis and evaluation of concentrations of heavy metals in farmland soil polluted by pollution water leakage during high-risk arsenical chemicals destruction in Nanjing were carried out by the statistical analysis of survey data and distribution of concentrations of heavy metals were also studied. Then four kinds of heavy metals in the contaminated area were identified out of seven kinds. Different evaluation standards were adopted to evaluate the heavy metal pollution by using the method of pollution index. The results showed that the main pollutants in the research area were As, Cr, Cu and Hg, among which As and Cr were associated with the event and could also be affected by the surrounding residents＇ living activities. While the pollution sources of Cu and Hg had nothing to do with the event. The complex pollution index of heavy metals accumulative pollution was 3.57 if taking the upper limit of regional control point （St-l） as evaluation standard, which indicated that the soil was severely contaminated by Cu and Hg. While evaluated with the secondary standard （St-2） of Environmental quality standards for soils （GB/T 15612-1995） and the limited values of Farmland environmental quality evaluation standards for edible agricultural products （HJ 332-2006） as assessment standard, the complex pollution index of heavy metals were 1.58 and 1.60, which meant that it was not suitable for planting pollution-free vegetables or other corps for eating in the area. But if assessed with guidelines for health risk to heavy metals in vegetable plantation soils （St-3）, those edible plants such as leafy and melons in the contaminated area maybe posed in hazard due to their different absorbency of heavy metals.