典型岩溶槽谷区不同地表覆被土壤中多环芳烃的运移特征和来源解析

为探究岩溶槽谷区土壤中多环芳烃(PAHs)的环境行为,选取典型的竹林地、灌丛地和耕地作为研究对象,运用气相色谱-质谱联用仪定量分析土壤中的PAHs.结果表明,土壤剖面中PAHs污染水平表现为竹林地(204.13 ng·g^-1)>耕地(175.47 ng·g^-1)>灌丛地(106.00 ng·g^-1),土壤质量总体良好.3种土地类型均表现为浅层土壤的PAHs含量显著高于深层土壤(p<0.05),表明岩溶区土壤对防止地下水污染具有重要意义;2~3环PAHs易运移至深层土壤,而4~6环PAHs受TOC含量的影响则主要积聚在浅层土壤,富集能力表现为灌丛地>耕地>竹林地;PAHs运移特征主要受控于有机质的吸附和水的溶解两种机制,PAHs和土壤的理化性质是影响PAHs运移的重要因素.结合同分异构体比值法和主成分分析法的源解析结果,得出研究区土壤中PAHs主要源于当地能源燃烧和交通污染,而大气沉降是重要污染途径.

Migration characteristic and source analysis of PAHs in soils with different surface cover in typical Karst trough Valley Area

Typical bamboo forest land, shrub land and cultivated land in a typical karst trough valley area were selected to study the environmental behavior of PAHs by quantification of gas chromatography-mass spectrometry. Our results revealed that the PAHs pollution level in soil profiles was bamboo forest land (204.13 ng·g^-1)>cultivated land (175.47 ng·g^-1)>shrub land (106.00 ng·g^-1), and the soil quality was generally good. Among the three land types, the content of PAHs in surface soil was significantly higher than that in bottom soil (p < 0.05), indicating that the soil in karst area was of great significance for prevention of groundwater pollution; 2~3 ring PAHs could easily migrate to bottom soil layer, while 4~6 ring PAHs were mainly accumulated in surface layer, along with TOC content, and the ability to concentrate PAHs was shrub land>cultivated land>bamboo forest land; the migration characteristic of PAHs was mainly subject to adsorption of organic matter and dissolution of water, and physicochemical properties of PAHs and soil were important factors affecting the migration ability of PAHs. Source analysis results obtained by using isomer ratio method and principal component analysis method, revealed that the PAHs in soils of study area came from local energy combustion and traffic pollution,and atmospheric deposition was an important route of pollution.