典型污染区农业土壤中PAHs的分布、来源及生态风险

Distribution,sources and ecological risk assessment of polycyclic aromatic hydrocarbons in agricultural soils from a typical contaminated area

采用同位素稀释气相色谱-质谱(GC/MS)分析了路桥农业表层土壤中16种优控PAHs的含量,并对其分布、来源及生态风险进行了分析.结果表明,土壤中16种PAHs的检出率达到100%,其总含量范围为52.3～991μg·kg-1,与土壤有机碳显著相关(p<0.01).PAHs组成特征表明,路桥土壤中以高环PAHs为主.PAHs(除Nap、Acy和Fl)间呈显著相关(r>0.7,p<0.01),表明采样区PAHs污染来源具有一定的相似性.同分异构体比值和因子分析表明,路桥农业土壤中PAHs主要来源于煤和生物质的燃烧.土样中16PAHs的毒性当量浓度(TEQBaP)介于4.61～164μg·kg-1之间,7种致癌性PAHs对总TEQBaP的贡献达99%.在35%的土样中,10种PAHs的总TEQBaP超过荷兰土壤目标参考值,表明路桥部分农业土壤存在潜在的生态风险.

The concentrations of 16 US EPA PAHs in agricultural soils from Luqiao were analyzed by isotope dilution GC/MS,and their distribution,sources and ecological risk were investigated.Each of the 16 PAHs was detected in all of the soil samples.The total concentrations of PAHs in the soils ranged from 52.3 to 991 μg·kg-1,which correlated significantly with soil organic carbon content（p 〈 0.01）.The PAH constituents indicated that high molecular weight PAHs were dominant in Luqiao soils.The good correlation（r 〉 0.7,p 〈 0.01）among PAH components（except Nap,Acy and Fl）indicated that the PAHs in the sampling area may have similar origins.The isomer ratios and factor analysis revealed that the PAHs in the Luqiao agricultural soils originated mainly from coal and biomass combustion.The toxic benzo[a]pyrene equivalents（TEQBaP）of the 16 PAHs ranged from 4.61 to 164 μg·kg-1,99% of which was contributed by 7 carcinogenic PAHs.The total TEQBaP of 10 PAHs with target value in 35% of the soil samples exceeded the Dutch target reference value,suggesting that some agricultural soils in Luqiao may have potential ecological risk.