城乡结合带农田土壤多环芳烃空间分布特征及来源解析-以南京市周岗镇为例

Spatial Distribution and Sources of PAHs in Farmland Soil of Peri-urban Areas:A Case Study of Zhougang,Nanjing

为了解城乡结合带农田土壤PAHs的污染特征及分布规律,本文以南京市江宁区周岗镇为例,就该地区表层农田土壤中15种优控PAHs组分的含量、空间分布特征及来源进行了研究。结果表明:有14种PAHs普遍被检出(苊未检出),以高环(4~6环)PAHs为主;PAHs总量范围在24.49~750.04μg kg-1之间,平均为230.89μg kg-1,有48.28%的土样受到了污染;与国内其他地区农田土壤相比,研究区PAHs含量处于中低水平;空间趋势面分析表明,14种PAHs在东西和南北方向上呈现出明显的规律增减性;从空间分布格局来看,研究区土壤中14种PAHs含量差异较大,整体呈现由东北向西南递减的趋势,且个别点位存在PAHs的富集现象,存在局部点源污染;采用主成分及多元线性回归分析污染来源,结果显示,研究区PAHs来源主要为煤、生物质燃烧,其次为汽油、柴油燃烧,贡献率分别为71%和29%,这与当地的工业发展水平关系密切。

In order to understand the pollution characteristics and distribution of PAHs in farmland soil of peri-urban areas,a case study of Zhougang of Nanjing was carried out to investigate the content,spatial distribution characteristics and sources of 15 optimal PAHs components in topsoil.Results showed that 14 PAHs were detected(Ace was not detected),and most of them were high loop(4-6 rings)PAHs.The total content of PAHs in farmland soil ranged from24.49 to 750.04μg kg-1 with an average value of 230.89μg kg-1.About 48.28%of farmland soil in this study area was polluted.Compared with the other farmland soil in China,the PAHs contents in this study area were at medium and low levels.The spatial trend analysis showed obvious increasing or decreasing regularity in east-west and north-south direction for the total content of 14 PAHs.According to the spatial distribution characteristics,the 14 PAHs contents in the farmland soil were significantly different and overall showed a decline from the northeast to southwest areas.There was a certain accumulation of PAHs at some points,where existed local point source pollution.The results of principal component analysis(PCA)and multiple linear regression showed that the main sources of 14 PAHs in the study area were coal and biomass combustion,followed by the combustion of gas and diesel oils,with contribution rates of 71%and 29%,respectively,which were closely related to the local industrial development level.