北京市表层土壤中PAHs含量特征及来源分析

土壤,作为城市中最重要的环境介质,承担了较高多环芳烃(PAHs)的环境负荷,开展土壤PAHs分布特征及来源分析研究,可以为污染风险防控、环保政策制定提供支撑.为研究北京市不同功能区土壤环境中PAHs的含量、组成及来源,本文在北京市主城区进行了大范围采样,同时针对工业区、农业种植区、水源保护区及居民区等不同功能区进行了分...

The Content Characteristics and Source Analysis of Polycyclic Aromatic Hydrocarbons in Topsoil of Beijing City

BACKGROUND:Polycyclic aromatic hydrocarbons(PAHs),as a typical persistent organic pollutant,widely exist in the environment and have high stability.Studying of the content distribution and source analysis of PAHs in soil will provide a technical basis for PAHs pollution prevention and control,ecological environment improvement and environmental protection policy-making.OBJECTIVES:In order to investigate the content,composition and source of PAHs in the soil environment of different functional areas in Beijing City.METHODS:A large-scale sampling was carried out in the core area of Beijing City.At the same time,regional sampling was carried out for different functional areas such as industrial areas,agricultural planting areas,water source protection areas and residential areas.A total of 459 topsoil samples were collected,and the monomer contents of 16 PAHs were analyzed by gas chromatography-mass spectrometry(GC-MS).RESULTS:The average values of the total contents of 16 PAHs(∑16 PAHs)in topsoil of the three subregions in the core area(southeast,center and northwest)were 153.7,333.2 and 142.9μg/kg,respectively.The average values of∑16 PAHs in topsoil of the industrial zone,including Southeast Factory,Shougang Industry and Datai Coal Mine,were 1006.9,1379.4 and 146.8μg/kg,respectively.The average values of∑16 PAHs in topsoil of the water-conserving areas,Huairou and Miyun,were 86.4μg/kg and 154.5μg/kg,respectively.The average values of∑16 PAHs in topsoil of four agricultural planting regions(Changping,Pinggu,Fangshan and Tongzhou)were 109.0,118.3,106.8 and 94.2μg/kg,respectively.The average value of∑16 PAHs in topsoil of residential areas was 131.1μg/kg.Compared with previous research results on the content and distribution characteristics of PAHs,the content of PAHs in the topsoil in Beijing City showed a decreased trend,which was related to the decrease in the use of coal and the increase in the use of natural gas in Beijing City in recent years.The composition of PAHs in different functional areas was different.The proportion of heavy and medium rings PAHs were higher in industrial areas.The proportion of light rings PAHs in water-conserving areas,agricultural planting regions and residential areas was higher than that in industrial areas,which might be due to the different sources of PAHs in different functional areas.The results of principal component analysis-multiple linear regression method showed that the main sources of PAHs in the core area were tail gas emissions and leakage during oil storage and transportation,which contributed 81.46%and 18.54%,respectively.The main sources of PAHs in the topsoil of the industrial area were coal combustion and tail gas emissions,which contributed 62.65%and 37.35%,respectively.The main sources of PAHs in residential areas were tail gas emissions and natural gas combustion sources,with contribution rates of 53.30%and 46.70%,respectively.CONCLUSIONS:Further strengthening traffic control,continuing to reduce the proportion of coal in energy structure,and increasing the proportion of clean energy are effective ways to reduce PAHs emissions and pollution in Beijing City.