Source Tracing Of Biomarkers In The Organic Pollutants From Atmospheric Particulates In Beijing City

The pollution caused by atmospheric particulates is one of the important factors affecting the urban air quality, which has been the chief air pollutant in many middle-large-sized cities like Beijing in our country.In order to analyze the pollution level and the source of organic matter in atmospheric particulates in Beijing city, the authors sampled PM₁₀ and PM_2.5 at nine areas in Beijing city during summer and winter between 2005 and 2006. The spatial distribution, seasonal variation features and temporal variation features of atmospheric particulates were analyzed through the comparison of the mass concentrations of PM₁₀ and PM_2.5 sampled at different areas during different periods, and the influence of meteorological factors was analyzed based on the relationship of the mass concentrations of PM₁₀ and PM_2.5 with weather conditions such as temperature, wind speed and relative humidity; the authors had researched on the concentrations of organic matter and the group components from PM₁₀ and PM_2.5, The aliphatic components in solvable organic matter were analyzed by GC-MS, the n-alkane homologs from C₁₄ to C₃₇, 33 kinds of terpenoids and 22 types of steranes were detected. The tracing study on pollutant source using some molecular geochemical parameters was conducted. The carbon isotopic compositions of n-alkane series were analyzed by GC-C-IRMS, and the characteristics and distributions of the carbon isotopic compositions of n-alkane series from atmospheric particulates in Beijing city have been studied as well.The results are concluded as follows: Because of the influence of pollution sources at each sampling area, the mass concentrations of PM₁₀ and PM_2.5 in different regions of Beijing city are different from the others, and it also shows that not all the spatial distribution regulations of the mass concentrations of PM_2.5 are the same as PM₁₀ on the whole at the same sampling area and the same time; the mass concentrations of atmospheric particulates in different regions during winter are higher than summer; As weather conditions keep stable, the hourly variation of PM₁₀ and PM_2.5 concentrations presents regularly, the temporal variation mostly depends onthe variety of contaminations released to the environment; Weather conditions are the important influence factors of PM₁₀ and PM_2.5 pollution level, the mass concentrations of atmospheric particulates decrease with the rise of the temperature and wind speed, while they increase with the increase of relative humidity; the concentrations of organic matter in atmospheric particulates in Beijing city were high, the saturated hydrocarbons from each sampling area may be derived from both modern higher plants and incomplete combustion of fossil fuels to some extents; the distribution of hopanes in atmospheric particulates during summer clearly showed the impact of gasoline combustion exhausts, the seasonal differences in the distribution of pentacyclic triterpanes showed the influence of coal burning for space heating in winter; the distribution of steranes during summer suggested that the influence of coal burning and engine lubricants on them was similar, steranes in Beijing city during winter were found to be mainly from coal burning; the concentrations of ¹²C in the n-alkane series with high carbon numbers were more than n-alkane series with low carbon numbers , the δ¹³C values of n-alkane series with low carbon numbers increase from cleaning zone, traffic zone, business zone to industry zone because of the influence of different pollutant source; the δ¹³C values of n-alkane series in atmospheric particulates during winter was heavier than summer.