香港土壤研究 Ⅲ.土壤中多环芳烃的含量及其来源初探

HONG KONG SOIL RESEARCHES Ⅲ.PAHs CONTENTS IN SOILS AND THEIR ORIGINS

通过对香港地区53个土壤样品多环芳烃(PAHs)含量的分析,并利用GIS空间数据管理功能,揭示了香港土壤中PAHs的含量和空间分布特征,同时,运用比值法定性地判断了土壤中PAHs的来源。研究结果表明:香港土壤中可以检测出16种美国环保署规定的优控PAHs中的15种(二苯并(a,h)蒽未被检测到),郊野土壤中PAHs的平均含量为34.2±16.0μg kg-1,而城区土壤中PAHs的平均含量为169±123μg kg-1,港岛动植物公园土壤中的苯并(a)芘的含量最高达到了47.2μg kg-1。在PAHs的来源上,前者的PAHs可能主要来自山火焚烧,而后者可能主要与城区的汽车尾气排放有密切的联系。

Polycyclic aromatic hydrocarbons （PAHs） arc supposed to be ubiquitous in the environment. However, researches on PAHs of Hong Kong area used to be focused mainly on sediments, atmosphere and marine organisms in the past, and little was reported on the soils. A total of 53 surface （0 - 10cm） soil samples consisting of 45 ones from rural areas and 8 from urban areas were collected and analyzed for PAHs with a gas chromatograph in combination with a flame ionization detector （GC/ FID）. Distributions of PAHs contents in Hong Kong soils were presented with the aid of the geographic information system （GIS）, and the origins of PAHs were identified with the method of isomer ratio. The results indicate that all the 16 U.S. EPA priority controlled PAHs except Dibenz（a, h）Anthracene were detected in the soils of Hong Kong. PAHs contents were averaged 34.2 ± 16.0μg kg^-1 in the rural soils and 169± 123 μg kg^-1 in the urban soils. PAHs patterns varied to some extent as well between the urban and rural soils. Higher molecular PAHs, such as Benzo（b ＋ k）fluoranthene, were found much higher in the former than in the latter. Benzo（a） pyrene, that has been recognized as one of the carcinogenic chemicals by the International Agency for Research on Cancer （IARC）, was detected up to 47.2 μg kg^-1 in the soil in the Zoology and Botanic Garden of Hong Kong, which was twice the relevant target value of the Soil Protection Guidelines in the Netherlands. As for the PAHs origins, it seemed that the former mainly stemmed from biomass burning, such as hill fires whereas the latter was closely associated with vehicular exhaust.