兰炭厂污染防治设施车间土壤中多环芳烃的分布特征及风险评价

Distribution Characteristics and Risk Assessment of Polycyclic AromaticHydrocarbons in the Soil of the Pollution Prevention and ControlFacilities Workshop of the Semi-Coke Plant

兰炭是低阶煤在密闭环境下热解干馏的固体产物。兰炭生产的低温干馏过程可能会产生一定的多环芳烃(Polycyclic Aromatic Hydrocarbons,PAHs),环境风险高。研究选取10家相同生产工艺的兰炭生产企业污染防治设施车间,对其氨水池和焦油池周边土壤中PAHs进行检测,分析其分布特征并进行风险评价。结果表明,16种PAHs在研究区均被检出,场地土壤PAHs污染分布比较普遍;各土层PAHs含量的排序为表层(167.74 mg/kg)>深层(82.32 mg/kg)>中层(20.55 mg/kg),基本符合土壤的富集规律;萘和苯并[a]芘含量超出二类建设用地筛选值,经毒性当量法评价,各土层PAHs的生态风险排序为中层>表层>深层。

Semi-coke is a solid product of the pyrolysis and distillation of low rank coal in a closed environment,and the low-temperature distillation process of semi-coke production may produce certain Polycyclic Aromatic Hydrocarbons(PAHs),which poses high environmental risks.This study selects 10 pollution prevention and control facility workshops of semi-coke production enterprises with the same production process to detect PAHs in the soil around their ammonia and tar tanks,analyze their distribution characteristics,and conduct risk assessments.The results show that 16 types of PAHs are detected in the study area,and the distribution of PAHs pollution in the soil of the site is relatively common;the ranking of PAHs content in each soil layer is surface layer(167.74 mg/kg)>deep layer(82.32 mg/kg)>middle layer(20.55 mg/kg),which basically conforms to the enrichment law of soil;the content of naphthalene and benzo[a]pyrene exceeds the screening value for ClassⅡconstruction land,according to the toxicity equivalent method evaluation,the ecological risk ranking of PAHs in each soil layer is middle layer>surface layer>deep layer.