珠江三角洲典型区域农业土壤中多环芳烃的含量分布特征及其污染来源

Source and Distribution Characteristics of Polycyclic Aromatic Hydrocarbons in Agricultural Soils in the Pearl River Delta

2002-10～2005-11采集珠江三角洲典型区域（东莞市、惠州市、中山市、珠海市和佛山市顺德区）的农业土壤表层样品260个,运用气相色谱-质谱方法对美国EPA优控的16种多环芳烃（PAHs）进行分析测定.结果显示,研究区农业土壤中16种PAHs含量范围在3.3～4 079.0 ng·g^-1,平均含量244.2 ng·g^-1,以3环和4环的PAHs为主;中心城区土壤中PAHs含量高于远郊区,菜地＞水稻田＞香蕉地＞旱坡地果园地＞甘蔗地.依据荧蒽/芘及2＋3环与4环以上PAHs化合物分布特点,表明该区域农业土壤中PAHs主要来源于化石燃料的不完全燃烧.通过与国内外土壤中PAHs含量的对比,研究区的农业土壤受到一定程度的PAHs污染,含量处于中等水平.

260 samples of surface agricultural soils （0 - 20 cm depth） were collected in the typical areas of Pearl River Delta from October 2002 to November 2005.The concentrations of polycyclic aromatic hydrocarbons （16 US EPA priority PAHs） in the collected soil samples were determined by gas chromatography equipped with a mass spectrometry detector （GC-MS）. The results showed that the concentrations of ∑PAHs in the collected soil samples ranged from 3.3 to 4 079.0 ng·g^-1 with the average concentration of 224.2 ng·g^-1. PAHs in the collected samples were dominated by its 3-ring and 4-ring members. There were the higher concentrations of ∑ PAHs in the collected samples of urban sites than those of remote sites. The concentrations of ∑ PAHs in the collected samples related to different land use types the order： vegetable soils 〉 paddy soils 〉 banana soils 〉 orchard soils 〉 sugarcane soils. According to the distributions of fluoranthene/pyrene, 2 ＋ 3 ring and 4 ring PAHs in these regions, it is supposed that the major contribution to the pollution of PAHs in these typical areas might be the incomplete combustion of fossil fuel. Compared with those in other national or international regions, the concentrations of ∑PAHs in these typical regions were moderate.