太原小店污灌区农田土壤多环芳烃的污染特征及其来源

[目的]对太原小店污灌区农田土壤多环芳烃(PAHs)的污染特征及来源进行分析,为该区农田土壤环境质量评价及土壤污染防治对策的制定提供科学依据。[方法]采集太原小店污灌区15个表层土壤样品,利用GC/MS分析16种US EPA优控多环芳烃(PAHs)的含量,并对其来源和生态风险进行探讨。[结果]所有样品的16种PAHs均被检出,其检出率为100%。研究区农田土壤中总PAHs的浓度为0.315~7.661μg/g,平均值为3.568μg/g。在组成上,2,3环含量约占总量的64.2%,4环含量约占总量的14.2%,5,6环含量约占总量的21.6%,低环和中环PAHs含量所占的比例较高。根据特征比值法及调查结果判定,农田土壤中PAHs污染来源一方面与灌溉水质及灌溉历史有很大的关系,另一方面,主要通过燃煤或化石燃料产生的PAHs在大气干湿沉降和风力输送作用下进入到土壤环境中。[结论]与国内外其他地区的相关研究比较,小店污灌区农田土壤PAHs含量处于中高等污染水平。依据Maliszewska-Kordybach建议的分级标准评价,该区域所有采样点PAHs总量均超标;但基于我国《土壤环境质量标准(征求意见稿)(GB15618-2008)》提出的16种多PAHs污染物总量的农业用地标准值,该区域均未超出此标准。

Pollution Characteristics and Sources of Polycyclic Aromatic Hydrocarbons in Farmland Soil of a Sewage Irrigation Area

[Objective] This study analyzed the pollution characteristics and sources of polycyclic aromatic hydrocarbons(PAHs) in farmland soil from Xiaodian sewage irrigation area in Taiyuan City.The results should facilitate the development of farmland environment evaluation and soil pollution prevention strategy in the study area.[Methods] 15 surface soil samples were collected,and their concentrations and composition of 16 PAHs listed for prior control by US EPA were detected with a gas chromatography equipped with mass spectrometry (GC/MS).The sources and ecological risks of the soils were assessed.[Results] The results showed that 16 PAHs were generally detected,with the detection ratio of 100％.The total PAHs concentrations varied from 0.315 to 7.661 μg/g,with an average value of 3.568 μg/g.In terms of composition,the contents of PAHs of 2,3 rings accounted for 64.2％ of the total PAHs,the contents of PAHs of 4 rings accounted for 14.2％,and the percentage of 5,6 ring-PAHs was 21.6％.Thus,the contents of PAHs with low and middle rings were much higher.Based on ratio method and in-site investigation,it was induced that the PAHs sources were not only related with water quality and history of sewage irrigation,but also with the sources from the combustions of wood,coal and fossil fuels.[Conclusion] Compared with the relative research of farmland soils at home and abroad,PAHs pollution in this area was in medium or higher level.According to the standards recommended by Maliszewska-Kordybach,the total concentrations of PAHs exceeded the limited value in all the sampling points.However,these values were below the "National Environmental quality standards for soils (GB15618-2008)" proposed by China.