Study On The Characteristics And Transformation Of VOCs In Ambient Air Of Jinan City

Acquisition the data of56kinds ambient volatile organic compounds (VOCs) in Jinan city during June2010to May2012, using gas chromatography online monitoring, and on July1,2011to June30,2012, online monitoring of O3, NOx, and synchronous acquisition of PM2.5and meteorological data. With the analysis of the monitoring results, the sources and the transformation of VOCs component were studied in this study.The result shows that it was similar of total VOCs (TVOCs) change rule in June2010to May2010, TVOCs the average levels were:summer>autumn>spring>winter; The daily variation tendency of TVOCs show bimodal distribution, in conformity with the morning and evening rush hour. The VOCs in the air of Jinan urban district was the main species of the C3-C5alkanes, propylene, cis-2-butene, toluene and xylene, etc.,Different seasons of VOCs in the air of the main species, summer olefin proportion was higher than that of other seasons. Alkanes, alkenes and TVOCs were in clear the diurnal change of the concentration of TVOCs twin peaks, and aromatic hydrocarbon concentration variation regularity of bimodal characteristics was not obvious.To analysis the main sources of VOCs of Jinan city with the method of SPSS17.0principal factor analysis.The result show that the automobile exhaust emission factor F1(Factor1)contribution rate of70.704%, industrial emissions factor F2contribution rate was16.355%, the combustion emission factors (F3), the contribution rate of F3was8.298%, the major source of VOCs for automobile exhaust, industrial and combustion sources in Jinan city.Two years2010～2011and2011～2011O3concentration change trend, monitoring during the overweight, mainly in spring and summer. O3average concentration level summer>autumn>winter> spring. O3hour peak in the concentration variation trend are mainly concentrated in12:00～15:00.The relationship of NO, NO2and O3were most obvious in winter.Jinan city ambient LOH and OFP of VOCs change rule with months of concentration variation trend were consistent, VOCs concentration, LOH and OFP were bigger in summer, It was easy to occur complex period of atmospheric pollution. Jinan city ambient air VOCs chemical activity and has a good linear correlation between mixing ratio, shows that the chemical composition of VOCs in the air of Jinan urban district has certain stability; VOCs average KOH than vinyl KOH, MIR ethylene and its explanation of Jinan city environmental air VOCs chemical reactivity was stronger. Olefin volumetric fraction was far less than alkanes, but chemical reactivity contribution rate was highest, and cis-2butene, propylene, ethylene, butene, anti-2butene, isoprene, styrene,2-methyl-1-pentene, cis-dipentene, between, on-xylene, neighbors-three methyl benzene, toluene, xylene,4-trichlorobenzene1key active component and cyclopentane to Jinan, so Jinan city highly reactive species of VOCs to olefins, aromatics and cyclopentane contribution to environmental air activity also not allow to ignore.Jinan city environmental monitoring PM2.5daily average concentration in the air during a maximum of0.486mg/m3, the minimum value was0.016mg/m3, with a mean of0.123mg/m3. Concentration was higher than the autumn and winter seasons spring and summer. The diurnal variation of the concentrations of PM2.5was bimodal phenomenon. PM2.5concentrations, negative correlation with wind speed into good TVOCs and PM2.5concentrations into positive correlation. In addition to the summer, other seasons of PM2.5and O3concentration into negative correlation. PM2.5and the concentration of SO2and NOx were a good positive correlation.Using Fractional Aerosol Coefficient (FAC) estimate generation potential of SOA,56species of VOCs in Jinan urban district of SOA has generated potential of species with a total of25,10species of alkane, aromatic hydrocarbons has15species. SOA generation to an average of1.22μg·m-3in2011, SOA including alkanes and aromatic hydrocarbons generation accounted for11.27%and88.72%. Major species of VOCs that generate SOA were toluene, xylene, ethyl benzene, neighbors-xylene and benzene. Summer, spring and autumn was not conducive to the generation and accumulation of SOA, whereas in winter.