| Atmospheric fine particles PM2.5 plays an important role on atmospheric visibility, and climate change, atmospheric environment quality and human health,and is also thought to be important factors of urban and regional haze formation.The chemical composition of PM2.5, including non soluble minerals,water soluble inorganic salt and organic aerosols is also the important component. Due to the big difference on physical and chemical properties of organic matter and some very low concentrations in the atmosphere, which makes the characterization of particle organic matter from the molecular level is very difficult.At present about PM2.5 organic composition, formation mechanism and the understanding of the sources are still limited.In order to deepen the research of oxygenated organic compounds in Chinese megacity, atmospheric PM2.5 samples were collected at three representative sites(Industry zone, Traffic zone and Botanical zone) in Wuhan. Prepared PM2.5 samples were derivatized with BSTFA / TMCS, follow by GC-MS analysis.According to its mass chromatogram,characteristic fragment ions, the standard library and retention index, oxygenated hydroxy compounds such as sugars, n-alkyl alcohol, sterols,phthalates and other compounds were identified. The results were as follows:(1)Wuhan PM2.5 concentration ranged from 18.85 to 454.43 μg·m-3, the average concentration was 144.71 μg·m-3.(2)Levoglucosan was the highest of all saccharide component concentrations, which ranged from 147.49 to 2132.79 ng·m-3 and the highest point appeared in the autumn. Glucose and fructose showed the same trend,that was the highest content of autumn and lowest of summer. Sugar alcohols was in a low concentration on the range of 14.78-278.51 ng·m-3. The highest sucrose and trehalose concentration was 247.90 ng·m-3 and 27.34 ng·m-3 in autumn, much higher than the other three seasons.(3)The total concentration of n-alkyl alcohol is 12.38 ~ 74.54 ng·m-3. CPI ranged from 3.55 to 11.46 and showed a significant even-odd predominance and a trend of summer> spring> autumn> winter.(4)Three sampling points total sterol concentration ranged from 0.41 to 96.49 ng · m-3, with average concentration of 8.61 ng·m-3. The highest cholesterol concentration of Traffic zone was 9.52 ng·m-3. β- sitosterol and levoglucosan in the fall and winter showed the same trend may come from the same source.(5) Three sampling points concentration of phthalate acid esters were 762.26 ng·m-3,291.57 ng·m-3 and 537.11 ng·m-3,respectively. Phthalic acid esters were negatively correlated with temperature and wind speed and positively with the humidity. The proportion of Phthalic acid esters in organic matter was stably at between 0.02-0.04, basically out from external sources.(6)Wuhan Atmospheric PM2.5 were also detected catechol, dibenzofuran, nonanal, hydroxy acid, dehydroabietic acid and pinene acid 6 kinds of other oxygenated organics, these six kinds of oxygenated organic compounds as physical special chemical properties, often used as organic tracers.(7)Wuhan PM2.5 oxygenated organic compounds with factor analysis showed that the industrial zone had seven oxygenated organic sources, mainly three kinds of sources were biomass combustion(22.971%), plant released(14.187%) and soil resuspension(13.385%). Traffic zone oxygenated organic compounds had six sources, mainly three kinds of sources were soil resuspension(26.888%), biomass burning(20.421%) and plants released(14.131%). Botanical zone had four sources those were soil resuspension, biomass burning, cooking meat and plant released. |
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