Fixed-point And Mobile Measurements Of VOCs In Typical Cities In The Yangtze River Delta Region

In this study,we focused on the investigations of ambient volatile organic compounds（VOCs）in Shanghai and Nanjing,two typical cities in the Yangtze River Delta region of China（YRD）.VOCs measurement in urban Shanghai was conducted with the gas chromatography coupled with mass spectrometer and flame ionization detector（GC-MS/FID）from October 15,2018 to November 11,2018.The composition and variations of VOCs in Shanghai were determined,and the OH radical consumption rate and Maximum Incremental Reactivity（MIR）was calculated to reveal reactivity and OFP of VOCs in Shanghai.Sources and their contributions to VOCs were analyzed by using PMF.In Nanjing,we mainly used a SPI-MS and performed a highly-time resolved mobile measurement of the VOCs in the Nanjing Chemical Industry Park（CIP）.VOCs pollution characteristics in different areas along with the navigation route were depicted,as well as the calculations of OFP of different VOCs,thus providing details and insights into VOCs control in such environment.The average total VOCs concentration in Shanghai was 32.73±27.04 ppbv.Alkanes accounted for 41%of total VOCs mass,following with carbonyls（o-VOCs）（23%）,halo hydrocarbons（x-VOCs）（14%）,aromatics（10%）,alkenes（7%）and acetylene（5%）.Ethane was the one with highest concentration observed in Shanghai,accounting for 15.3%of the total VOCs concentration.The diurnal variation of VOCs presented a double-peak change,peaking at 7:00 in the morning and 21:00 at night.During the observation period,the atmospheric chemical reaction activity L^OH was 85.78s^-1 and OFP was 48.4 ppbv.Alkenes contributed the most to L^OH and OFP,accounting for 38.6%and 39%,respectively.PMF analysis resolved six sources of VOCs,which were secondary formation（29%）,gasoline evaporation（16%）,solvent usage（7%）,biogenic（8%）,vehicle exhaust（24%）and fuel combustion（16%）,respectively.Vehicles and fuel-related sources（traffic emissions,fuel combustion,and gasoline evaporation）together had the largest contribution to VOCs（56%）.The four-day mobile measurement conducted in Nanjing CIP determined that the average concentration of VOCs was 133.3μg/m³,of which the proportions of alkanes and aromatics were the highest（31%）,followed by alkenes（25%）and halocarbons（13%）.There were remarkable differences in the concentrations,compositions and sources in three different key areas along observation route.For example,VOCs in Nangang-Nanhua area mainly came from Nanhua and nearby companies,the VOCs in Yangzi Petrochemical mainly came from its aromatics plant,the VOCs in Huagong Road were emitted from pesticide production company,etc.The contributions to OFP of alkenes,aromatics,alkanes and halocarbons were 56%,32%,9%and 3%respectively.