煤气化污染场地土壤PAHs分布特征初探

Environmental Site Investigation and Distribution of Polycyclic Arolycyclic Aromatic Hydrocarbons for Coal Gasification Contaminated Sites

文章以某大型退役煤气厂场地为研究对象,分析了污染场地土壤中对人体危害风险性较大的化合物PAHs的含量与分布特征。采用气相色谱-质谱联用仪(GC-MS)对1234个样品中多环芳烃(PAHs)的含量进行检测。分析PAHs在煤气厂不同生产车间土壤的污染状况和深层土壤中的垂直分布特征。结果表明:土壤中总PAHs含量范围为1.67～19120.74 mg/kg,组成成分以2～3环为主,平均含量分别占总PAHs的31.5%和58.8%,其次为4环和5环,分别占总PAHs的7.5%和1.9%,最低为6环PAHs,仅占1.6%。随着土壤深度的增大,多环芳烃总量急剧降低。当土壤深度超过6 m,PAHs以2～3环为主。PAHs在土壤中的富集趋势为粗苯工段>冷鼓工段>污水处理区>脱硫工段>土地储备区>炼焦熄焦区>硫铵工段>综合油库>生产辅助区>煤气储藏及输送区>备煤与焦炭储藏区,且污染点位多数位于各工段的生产区域,说明土壤中PAHs的污染与原生产活动有一定相关性。

A field investigation was carried out for the site of a large coal gasification plant in Shanxi Province to explore content and distribution of PAHs, a kind of chemicals extremely hazardous to human health in the soil. The polycyclic aromatic hydrocarbons (PAHs) were analyzed by GC-MS in 1234 surface soil sample collected from the plant. The PAHs emission of different workshops and vertical distribution of PAHs were discussed. Results showed that total PAHs contents in soil ranged from 1.67 to 19 120.74 mg/kg. The composition of PAHs was characterized by low molecular weight PAHs. Dominant compounds were 2 rings and 3 rings PAHs, which accounted for 31.5% and 58.8%, followed by 4 and 5 rings, which accounted for 7.5% and 1.9% of the total PAH concentrations, respectively. The lowest was the 6 rings PAHs, which only accounted for 1.6% of the total PAH concentrations. The contents of PAHs decreased sharply with the increase in vertical depth. Low-ring PAHs became the priority compounds when the depth was over 6m. The enrichment of PAHs in soil was in order of crude benzene recycle area > the blast condense area > wastewater treatment area > desulfurization area > land reserve area > coking quenching area > ammonium sulfate area > integrated depot area > production aids area > gas storage and transportation area > coal and coke storage area. The sites of soil samples containing PAHs coincide with those of the workshops of the former coal gasification plant, indicating a strong relationship between the presence of PAHs in the soil and the production activities of the former plant.