山东省农田土壤多环芳烃的污染特征及源解析

Pollution Characteristics and Source Analysis of Polycyclic Aromatic Hydrocarbons in Agricultural Soils from Shandong

2015年7月采集山东省农田表层土壤,采用高效液相色谱紫外/荧光检测器串联方法对美国环保署优先控制的16种多环芳烃(PAHs)进行检测,分析了其含量和组成特点,比较了种植粮食作物的大田土壤和蔬菜大棚土壤、点源污染和非点源污染大田土壤中PAHs的差异,采用比值法和正定矩阵因子模型对PAHs来源进行解析,并评价了其风险.结果表明,16种PAHs总含量(Σ16PAHs)范围为111.5~2744.1 ng·g^(-1),均值为556.3 ng·g^(-1),与国内其他地区的农田土壤污染水平相比处于中等水平.组成上,苊、芴、荧蒽的比例较高,而茚并(1,2,3-cd)芘的比例较低.点源污染大田土壤中Σ16PAHs含量和7种致癌PAHs的比例均显著高于非点源污染大田;蔬菜大棚土壤与附近的大田土壤相比,Σ16PAHs含量没有显著差异,且均是3~4环PAHs比例较高.山东省农田土壤中的PAHs主要来自于燃烧源,其中燃煤和生物质燃烧占42.7%,交通产生的石油燃烧占19.3%,此外炼焦排放占22.8%,石油污染占15.2%.风险评估表明,山东省非点源污染大田土壤和蔬菜大棚土壤中总毒性当量含量均未超过加拿大土壤环境质量标准,但部分点源污染大田土壤超标,具有潜在的风险.

Polycyclic aromatic hydrocarbons（PAHs） are ubiquitous environmental contaminants that originate mainly from anthropogenic sources.PAHs have elicited much concern because they exhibit strong toxic,carcinogenic,and mutagenic properties.Agricultural soil is at risk of PAH contamination mainly caused by atmospheric depositions,wastewater irrigation,or organic substances and biowaste applied as fertilizers.The surface agricultural soils were collected from Shandong in July 2015,and measured for 16 US EPA priority PAHs using high performance liquid chromatography with UV and fluorescence detector.The content and composition of PAHs were analyzed.The differences of PAHs between soils from the field for growing crops and from vegetable greenhouses,and between soils from point sources and from non-point sources were compared.The sources of PAHs were determined with methods of ratio between PAHs and positive matrix factorization（PMF）,and the risks of PAHs were assessed.The results showed that the total content of 16 PAHs（Σ 16PAHs） ranged from 111.5 ng·g^-1to 2 744.1 ng·g^-1,with the mean of 556.3 ng·g^-1.The content of 3-ring PAHs was relatively high,with the mean of 201.5 ng·g^-1; while the contents of 2-ring and 6-ring PAHs were relatively low,with the mean of 39.3 ng·g^-1and 43.4 ng·g^-1,respectively.According to the contamination classification in Poland,71% of the samples in Shangdong were weakly contaminated.Compared with other areas in China,the content of PAHs in the agricultural soils in Shandong was in the middle range.Acenaphthene,fluorine,and fluoranthene were the major PAH compounds,accounting for more than 10% of the total PAHs; while the contribution of indeno（1,2,3-cd） pyrene was low.The content of Σ 16 PAHs and contribution of 7carcinogenic PAHs were significantly higher in soils polluted by point sources than those in soils from non-point sources.Moreover,the contribution of PAHs with 2-3 rings was significantly higher in soils from non-point sources,while the contribution of PAHs with 4-6rings was significantly higher in soils polluted by point sources.There was no significant difference in soils from vegetable greenhouses and from adjacent field soils,and the contribution of PAHs with 3-4 rings was high.The PAH isomer pair ratios of Ant/（Ant ＋ Phe）,Flu/（Flu ＋ Pyr）,Ba A/（Ba A ＋ Chr）,and In P/（In P ＋ BP） were utilized as molecular indices to elucidate the possible PAH sources,and the results suggested that the PAHs in the soils were mainly from combustion.To quantitatively assess the contribution of various sources to PAH contamination,PMF was used to analyze the sources.The sources of PAHs were combustion of coal biomass,oil combustion from traffic,coking,and petroleum pollution,with contribution of 42.7%,19.3%,22.8% and 15.2%,respectively.Toxic equivalency factors were used to evaluate PAH contamination in the soils,and the carcinogenicity of other PAHs relative to Ba P was quantified to estimate the Ba P-equivalent concentration（TEQBa P）.The TEQBa Pof 16 PAHs（Σ 16TEQBap） in soils from nonpoint sources and vegetable greenhouses was 31.69 and 44.47 ng·g^-1,respectively,which were below the safe value in Canadian soil quality guidelines.However,the Σ 16 TEQBapin some field soils from point sources exceeded the safe value,indicating that there were potential risks in the soils from point sources in Shandong.