| We developed a new separation method to purify the PAHs compounds in aerosol samples for compound specific stable carbon isotopic composition measurement. Particular samples of pollution sources and other common sites were collected in Guangzhou City, China, n-alkanes and non-alkylated polycyclic aromatic hydrocarbons were measured using GC-C-IRMS system to determine the characters of stable carbon isotopic composition of the samples, which may help us to apportion the sources of the pollutants. In addition, the range of the stable hydrogen isotopic composition for urban aerosols of Guangzhou City in order to test the hypothesis that stable hydrogen isotopic composition of individual n-alkanes can be used as an additional tool for source identification of aerosols.We get the following conclusion from the results:1. The ultrasonic extraction and silica gel/neutral aluminium dioxide column chromatography with thin layer chromatography (TLC) were combined to separate and purify the PAHs in aerosols samples, when the silica gel works as the stationary phase and developed in the mixture hexanexhloroform = 45.:5 ( V:V), the good purify effect can be gained. PAHs compounds separated by this method can be used for GC-C-IRMS measuring. This separate method is highly selected to the PAHs compounds with more than 3-ring. Compared to the other separation methods of PAHs used for GC-C-IRMS measurement reported before, this method has many advantages: high efficiency in low cost, the operation is easy and can be finished in short time, is high selectively to PAHs more than three rings.2. The results of the measuring of the different sources indicated that: the δ13C value of PAHs for fossil fuel combustion is the heaviest, and the δ13C value of PAHs from biomass combustion is the lightest. With the weight of the molecular increased, the the δ13C value of PAHs from cooking source is the increased too and their the δ13C value is lighter than PAHs from other sources (such as fossil fuel (coal) combustion, and biomass combustion). This difference means the measurement of δ13C value used to the source apportionment of PAHs inenvironment is feasible.3. Using the GC-C-IRMS technique to identify the source of urban aerosols of Guangzhou City, the results indicated that the main source of PAHs in urban aerosols of Guangzhou City is the automotive exhausts.4. There are no significant differences between δ13C value of n-alkanes and i-alkanes in the tobacco organic extracts and the ETS organic extracts. The i-alkanes were more enriched in 13C than the n-alkanes. The δ13C value range of the i-alkanes is narrower than n-alkanes' in both two kinds of samples. The δ13C value range of the n-alkanes is similar to the C3 plant.5. The δ13C values of three new kinds of smoking indicators were measuring, and they are more enriched in 13C than the n-alkanes and i-alkanes compounds, their δ13C values are 4‰-8‰ heavier than the two others. The δ13C value character of these compounds is never reported before.6. The characters of stable carbon isotopic composition of n-alkanes from coal combustion dust and automotive exhausts were determined. The δ13C values of n-alkanes from automotive exhausts are enriched in 13C with the increasing of the length of the n-alkanes chains. The curve of the δ13C values to the molecular weight of n-alkanes from coal combustion dust in a shape of "V", the turning point is n-C25, both before and after this compound, the δ13C values always depleted in 13C.7. The stable hydrogen isotopic compositions of urban aerosols collected from different height and in different particle size were detected. The range of the difference between the n-alkanes is quantitatively larger than it of the stable carbon isotopic compositions. The difference due to the particle size and the collection height was not observed. The δ D of the n-alkanes from automotive exhausts enriched in D in a small slop with the increasing of n-alkanes molecular weight. In general, the even carbon-numbered compounds were more enriched inδ D than the odd carbon-numbered species in the urban aerosol sample was consistently observed in individual n-alkanes δ D characters of C3 plants, so the n-alkanes of urban aerosol is more or less affected by the vegetation of plants.
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