北京市某废弃焦化厂不同车间土壤中多环芳烃（PAHs）的分布特征及风险评价

以北京市某废弃焦化厂为研究对象,系统采集了6个车间0～4m深的26个土壤样本,利用GC/MS检测了U.S.EPA优控的16种多环芳烃(PAHs)的含量,分析了PAHs在焦化厂不同车间表层土壤的污染状况和深层土壤中的垂直分布特征并对土壤污染风险进行了评估.结果表明,1)该废弃焦化厂不同车间表层土壤(0～20cm)总PAHs(∑PAHs)的残留量介于672.8～144814.3ng·g-1之间;污染程度排序为:回收车间>老粗苯车间>焦油车间>炼焦车间>水处理车间>制气车间.2)该厂未受扰动的土壤样品显示PAHs主要聚集在表层土壤,并随着土壤深度的增加而迅速减少;其他样点由于土壤扰动,∑PAHs含量最大值出现在第三层土壤(80～180cm);该厂4m深底层土壤仍有高浓度PAHs,∑PAHs含量最高值出现在炼焦车间,达12953.1ng·g-1.3)焦化厂土壤PAHs污染主要集中在3环和4环的PAHs单体上,分别占到污染总量的51.3%和31.7%.4)根据Maliszewska-Kordybach的PAHs总量标准及加拿大土壤PAHs单体治理标准,该厂回收、老粗苯、焦油和炼焦车间表层和深层土壤PAHs含量均达到重污染水平,并对其周围土地带来较大风险,需要治理.

Distribution and Risk of Polycyclic Aromatic Hydrocarbons in Soils from Different Workshops of an Abandoned Coking Factory in Beijing

Contents and composition of 16 polycyclic aromatic hydrocarbons(PAHs)listed for prior control by U.S.EPA in 26 soil samples from 6 workshops of an abandoned coking factory in Beijing were detected with a gas chromatography equipped with mass spectrometry(GC/MS).The characteristics of the PAHs emission of different workshops and vertical distribution of PAHs were discussed.Results showed that:1)The total PAHs(∑PAHs)contents in topsoil(0～20cm)ranged from 672.8 to 144814.3ng·g-1,and the concentration sequence in different workshops showed Recovery workshop>Crude benzol workshop>Tar workshop>Coking workshop>Sewage treatment workshop>Gas workshop.2)In the no-disturbed soil samples,PAHs were accumulated in the topsoil and rapidly decreased with depth,while in disturbed soil samples,the maximum of ∑PAHs were detected in 80～180cm deep soil.What's more,4m deep soil in this factory were still badly polluted with a maximum of ∑PAHs in Coking workshop(12953.1ng·g-1).3)The contents of three and four rings PAH components were much higher than those of the other PAH components,which occupied 51.3% and 31.7% of the total PAHs,respectively.4)According to the criteria of Maliszewska-Kordybach and CCME,the contents of some PAH monomers in top soils and deep soils(80 ～400cm)of Recovery workshop,Crude benzol workshop,Tar workshop and Coking workshop were above the heavy pollution standard,which would lead to huge risks for surroundings.