焦化厂土壤中PAHs的累积、垂向分布特征及来源分析

Analysis on accumulation,distribution and origin of polycyclic aromatic hydrocarbons in soils under a coking plant

引言 多环芳烃（polycyclic aromatic hydrocarbons，PAHs）在环境中普遍存在，由于具有强烈的诱变、致癌和致畸作用而受到越来越多的关注。以煤为主要原料的焦化行业，是环境中人类活动产生PAHs的主要来源之一，其各个生产车间内化石燃料的不完全燃烧及焦油、煤气等化工产品的加工过程都可能导致PAHs的排放。

Anthropogenic polycyclic aromatic hydrocarbons （PAHs） are one of the most major pollutants in soil under coking plants. In order to understand the characteristics of accumulation and vertical distribution of 16 USEPA priority PAHs in soil, GC/MS was used to analyze 16 PAHs in 587 soil samples taken from different depths of 0-18 m under coking plant. The results showed that, the highest and average concentration of total PAHs were 14363.7 mg · kg^- 1 and 190.4 mg· kg^- 1 respectively, indicating that the soil under coking plant had been polluted. The dominant components were low molecular weight PAHs, accounting for about 85%. The concentrations of PAHs had obvious fluctuation at various layers, and their concentration change was parallel. There was an obvious cumulative effect in 5-6 m soil layer, which might be due to different filtration capability of soil in different layers and PAHs leaching ability. Based on the principal component and Q-clustering analysis, the entire soil profile could be classified into 5 different layers： 0-1 m, 1-3 m, 3-5 m, 5-6 m, 6-18 m. The concentration order of low molecular weight PAHs was 5-6 m〉0-1 m〉3-5 m 〉1-3 m〉6-18 m, whereas that of high molecular weight PAHs 0-1 m〉 5-6 m〉 1-3 m〉 3-5 m〉 6-18 m. Assessment of the PAHs compound ratios, Ant/（Ant＋Phe） and Flt/（Flt＋Pyr）, suggested that coal combustion was the main contamination source of the soil under this coking plant and the emission of coking gas and the leak of coal tar might also be primary contamination routes. In summary, the results in this paper illustrated the accumulation and distribution rules of PAHs in 0-18 m soil profile under a coking plant, and also provided some important data which would be used to manage the soil remediation and environment risk produced by coking industry.