某钢铁企业表层土壤中多环芳烃含量特征与生态风险评价

Concentration characteristic and ecological risk assessment of polycyclic aromatic hydrocarbons in the surface soils of a steel plant

采集我国某大型钢铁企业22个表层土壤(0—20 cm)样品,采用气相色谱-质谱(GC-MS)分析了其中16种多环芳烃(PAHs)的含量,并采用荷兰、加拿大土壤标准及苯并[a]芘的毒性当量浓度(TEQBa P)对PAHs生态风险进行评价.结果表明,土壤中∑16PAHs含量范围为21.0—20062.0μg·kg^(-1),平均值为2564.7μg·kg^(-1),单体以Flu、Pyr的含量最高,较之背景点土壤中PAHs含量,平均富集系数为22.9(Bk F)—304.0(Flu).与国内同类研究相比,该钢铁厂表层土壤中PAHs污染处于中等水平.各采样点中PAHs组成主要以4环为主,占31.9%—100%,5环组分仅次于4环.相关性分析表明,PAHs低环(2—3环)与中环(4环)组分之间相关性更强,且二者与TOC相关性较高环组分显著.50.0%的采样点超过荷兰土壤标准目标参考值,该钢铁厂表层土壤已处于中等风险水平,污染主要集中在球团厂、焦化厂、炼铁厂和厂前交通繁忙区.其土壤潜在风险已呈增加趋势,有必要进行能源结构改造并加强污染监控.

Polycyclic aromatic hydrocarbons（PAHs） were analyzed by GC-MS in 22 surface soil samples（0—20 cm） collected from a large steel plant in China. The concentrations of ∑16PAHs ranged from 21.0 to 20062. 0 μg·kg^-1with an average of 2564. 7 μg·kg^-1. Fluorine（Flu） and pyrene（Pyr） were the dominant compounds. The enrichment was significant for the 16 PAHs with the enrichment factors from 22.9（Bk F） to 304.0（Flu） in comparison with the relevant background value. The PAHs levels in the steel plant surface soils were generally moderate compared to those in soils from similar pollution sources. 4 and 5 rings PAHs were the dominant components,accounting for 31.9% to 100% of the ∑16PAHs. A correlation analysis showed that the total concentrations of PAHs and individual PAHs were significantly correlated,but the correlation was more significant for2—3 rings and 4 rings. The fractions of surface soil TOC had significant positive correlations with2—3 rings and 4 rings. The ecological risks of PAHs in the surface soils were evaluated by usingbenzo[a]pyrene toxice quivalents（TEQBa P）. Results showed that 50% of the surface soil samples were more than Dutch target values,which were located mainly in the coking plant,the pellet plant,the ironworks and the roadside heavy traffic area. PAHs pollution in the surface soils of the sampling area was at a moderate level. As the potential risk of the surface soils increased,it is necessary to change the energy structures and strengthen pollution surveillance.