天津地区典型土壤剖面多环芳烃的垂向分布特征

Vertical Distribution Characteristics of Polycyclic Aromatic Hydrocarbon Compounds from Various Soil Profiles of Tianjin

天津地区不同环境功能区表层土中均检出萘、苊、苊烯、联苯、菲、惹烯、芴、二苯并呋喃、二苯并噻吩、荧蒽、芘、屈、苯并芴、苯并蒽、苯并荧蒽、苯并芘、、二苯并[a,h]蒽、茚并[1,2,3-cd]芘、苯并[g,h,i]等多环芳烃化合物,但含量差别显著,南、北排污河污灌区多环芳烃含量明显高于非污染区及北部山区。不同剖面表土中多环芳烃的组成特征也存在明显差别,与非污灌耕地及北部山地相比,污灌耕地和滨海盐土耕地四环以上芳烃相对含量明显较高,而烷基取代物含量明显较低。剖面表层至40cm土壤中多环芳烃含量相对较高,深处含量明显降低,但不同剖面变化幅度存在明显差别,污灌耕地和滨海盐土耕地降低幅度最大,其它剖面变化较小,但剖面深部(>40cm)芳烃化合物组成特征基本趋于一致。

A series of polycyclic aromatic hydrocarbon compounds (PAHs) have been detected, including naphthalene, acenaphthene, acenaphthylene, biphenyl, phenanthrene, retene, fluorine, diphenylene oxide (dibenzofuran), dibenzothiophene, fluoranthene, pyrene, chrysene, benzfluorene, benzanthracene, benzo-fluoranthene, benzopyrene, perylene, dibenz[a,h]anthracene, indeno[1,2,3-cd]pyrene, benzo[g,h,i]perilene, triaromatic-terpane and their homologous compounds, in surface soil samples collected from various profiles with different environment conditions in Tianjin. The concentrations of PAHs are obviously difference in the surface soil samples collected from different profiles. It is relatively high from the sections in wastewater irrigated cropland than in the fresh water irrigated area or north mountainous area. The concentration of PAHs in depth of 30-40 cm in the vertical section is relative high and it is declined with depth in various sections. The chemical composition of PAHs are difference in the surface soil samples from different profiles. The concentration of 4-6 ring aromatic hydrocarbon compounds is relatively high in the surface soil samples from the sections of wastewater irrigated area and alkali soil (plowland) as compared to fresh water irrigated cropland and north mountainous area, but the contents of alkyl-substitute of polycyclic aromatic hydrocarbon are lower obviously. The concentration of PAHs in all seven profiles shown similar trend declined with depth. However, the range of variation in various soil profiles is difference. The range of variation are relatively high in the soil profile of wastewater irrigated area and alkali soil and relatively lower in others. The constitute of PAHs in the deep part of vertical section (>40cm) are trend consistent in each profiles.