基于GIS及APCS-MLR模型的兰州市主城区土壤PAHs来源解析

Source Apportionment of Soil PAHs in Lanzhou Based on GIS and APCS-MLR Model

为了解兰州市主城区表层土壤多环芳烃(PAHs)的污染现状,采集兰州市主城区表层土样62份,利用GC-MS(气相色谱-质谱联用仪)分析土样中16种优控PAHs的含量,采用描述性统计方法表征PAHs污染特征,运用APCS-MLR(绝对主成分分析-多元线性回归)模型判断土壤PAHs的来源,并验证模型结果的准确性,最后结合地统计方法确定各PAHs来源的主要影响区域.结果表明,兰州市主城区表层土壤Σ16 PAHs的含量为1069~7377μg·kg^(-1),平均为2423μg·kg^(-1);其中,以4~6环的高分子量PAHs为主,占Σ16 PAHs的质量分数为72.81%.APCS-MLR模型验证结果表明,实测值与预测值吻合性较高,该模型对于研究区土壤PAHs源解析有很好的适用性.兰州市主城区表层土壤PAHs的来源主要为交通排放源(35.42%)、石油排放源(29.88%)和煤炭与生物质燃烧混合源(33.91%),高值区主要分布在交通密集范围和工业区.结果表明研究区土壤PAHs来源复杂,且受人为活动的影响较大,应根据各污染源的贡献率和影响区域加强控制,以减少污染源排放量,从而降低土壤PAHs的污染程度.

To evaluate the pollution by polycyclic aromatic hydrocarbons(PAHs)in the surface soil of the core urban area of Lanzhou,62 topsoil samples were collected from the area.The soil samples were analyzed for the content of 16 priority PAHs,using gas chromatography-mass spectrometry.Descriptive statistical methods were used to characterize contamination by PAHs.An absolute principal component analysis-multiple linear regression(APCS-MLR)model was applied to determine the sources of PAHs in the soil samples,and the accuracy of the model results was verified.Finally,the main influence regions of each source were determined with a geo-statistical method.The results showed that the contents ofΣ16 PAHs in the surface soils of Lanzhou ranged from 1069 to 7377μg·kg^(-1),with an average of 2423μg·kg^(-1).High molecular weight PAHs(4-6 rings)were dominant,accounting for 72.81%of theΣ16 PAHs.Verification results of the APCS-MLR model showed that the measured values were in good correspondence with the predicted values,which indicated that the model had good applicability for source apportionment of soil PAHs in the study area.The main sources of PAHs in Lanzhou were traffic emissions(35.42%),petroleum emissions(29.88%),and a mixture of coal and biomass combustion(33.91%).The sources were greatly affected by human activities,and high values were mainly distributed in traffic-intensive and industrial areas.The results indicated that the sources of soil PAHs were complex and influenced by anthropogenic activities in the study area.Stringent control measures should be placed on the sources and areas of influence that contribute to soil PAHs to reduce the emissions and the level of soil pollution resulting from PAHs.