三峡库区消落带土壤中多环芳烃的污染特征、来源分析及生态风险

Pollution Characteristics,Source Identification and Ecological Risk of P olycyclic Aromatic Hydrocarbons in Soil of Water-Level Fluctuation Zone in The Three Gorges Reservoir

本研究分析了三峡库区重庆段典型区域消落带土壤样品中16种多环芳烃(polycyclic aromatic hydrocarbons,PAHs)的浓度水平,探讨了其空间赋存特征,通过空间变异特征分析和同族体比值分析阐明了不同高程土壤中PAHs的特异性分布及其可能来源,并采用风险商值法评价了PAHs的生态风险。结果表明,7个消落带土壤中∑PAHs的含量范围为180.2~618.0 ng·g^(-1)(以干质量计),中值为421.1 ng·g^(-1)(以干质量计),处于中低度污染水平。16种PAHs均有检出,菲是丰度最高的单体,贡献率为19.5%~32.8%。ΣPAHs在不同高程土壤中含量范围为281.0~794.1 ng·g^(-1)(以干质量计),中值为610.2 ng·g^(-1)(以干质量计),整体呈现随高程增加而浓度升高的趋势。PAHs以3环和4环为主,PAHs变异系数达到中度变异程度,人为活动和水位波动对消落带土壤中PAHs浓度影响较大。生态风险评价结果显示消落带土壤中荧蒽、[艹屈]、苯并[b]荧蒽、苯并[k]荧蒽、苯并[a]芘和苯并[g,h,i]芘达到高风险等级。同族体比值表明,生物质和化石燃料的不完全燃烧是消落带土壤中PAHs的主要来源。研究结果为三峡库区PAHs污染防控提供了有益参考。

Soil samples were analyzed in the water-level fluctuation zone of Chongqing from the Three Gorges Reservoir for the content and distribution characteristics of polycyclic aromatic hydrocarbons(PAHs).Meanwhile,PAH congeners were analyzed and the potential sources of PAHs in soil were identified by isomer ratio,and the e cological risk of PAHs was evaluated by ecological risk model.The results showed that the content of∑16PAHs in these regions ranged from 180.2~618.0 ng·g^(-1)(based on dry mass),and the median value was 421.1 ng·g^(-1)(based on dry mass),which was in the medium-low pollution level.All 16 kinds of PAHs were detected,and p henanthrene was the monomer with the highest abundance,which accounted for 19.5%~32.8%of∑16PAHs.The content ofΣ16PAHs in these different elevations ranged from 281.0~794.1 ng·g^(-1)(based on dry mass),with the median value of 610.2 ng·g^(-1)(based on dry mass),showing an increasing trend with the increase of elevation.Whereas the composition ratio of PAHs was dominated by 3-and 4-rings.The composition of PAHs in soil e xhibited a moderate coefficient of variation.Human activities and water level fluctuation had a great influence on the distribution of PAHs in the soil from different elevations.Ecological risk assessment results showed that the f luoranthene,chrysene,benzo[b]fluoranthene,benzo[k]fluoranthene,benzo[a]pyrene,and benzo[g,h,i]perylene reached high-level risk.The isomer ratios indicated that incomplete combustion of fossil fuels and biomass were the main sources of soil PAHs.The results provided a theoretical reference for the prevention and control of PAHs in Chongqing of the Three Gorges Reservoir.