用气相色谱-质谱联用(GC/MS)的方法分析太原市小店污灌区9个土壤剖面中16种多环芳烃(PAHs)含量及垂直分布特征.结果表明,小店污灌区表层土(0~10 cm)中PAHs平均含量变化趋势为背景区〈沼泽区〈清灌区〈污灌区;大部分剖面土中PAHs含量随土层深度增加呈减少趋势,PAHs含量变化幅度较大的位置集中在地表以下0~40 cm范围内;高环(4~6环)PAHs大量富集在距地表0~50 cm土壤内,清灌区土壤对4~6环PAHs的富集能力强于污灌区;不同环数PAHs与TOC和砂粒呈正相关关系(rmax=0.791,P=0;rmax=0.882,P=0),与pH呈负相关关系(rmin=-0.1,P=0.702);距地表0~40cm范围内的土壤中PAHs的主要污染来源为小店区煤的燃烧;燃烧产生PAHs的污染途径一是直接沉降至土壤中,二是沉降至水体中,吸附在固体颗粒表面,随着灌溉污水流动而在土壤中大量富集.
Nine profile soil samples were collected from Xiaodian sewage irrigation area,Taiyuan city,China.The concentrations of 16 polycyclic aromatic hydrocarbons(PAHs) were analyzed by gas chromatography equipped with a mass spectrometry detector(GC/MS).The rank order of the average concentrations of PAHs in the 0-10 cm upper soil layer was background areaswamp areagroundwater irrigation area sewage irrigation area.The concentrations of PAHs in most profile soils decreased with the increase of depth,and the PAHs were mainly accumulated in the surface soil layer(0-40 cm).4-6 rings of PAHs were mainly accumulated in the 0-50 cm soil layer,and the accumulation capacity in groundwater-irrigation area was better than that in sewage irrigation area.The correlation between different rings of PAHs and TOC was positive(rmax=0.791,P=0),and the same situation was found for PAHs and sand(rmax=0.882,P=0).The correlation between PAHs and pH was negative(rmin=-0.1,P=0.702).The main source of PAHs in the surface soil layer(0-40 cm) of study area was coal combustion.There were two pollution ways of PAHs in soil,one was settled into soil directly,the other was first settled into water and absorbed on the surface of solid particles,and then got enrichment in soil as irrigation water flew.