The Study Of The Source Apportionment And Photochemical Properties Of VOCs In The Northern Suburb Of Nanjing

Hourly concentrations of ambient volatile organic compounds (VOCs) were sampled in the northern suburb of Nanjing by on-line GC5000instrument. Combined with the regular meteorological data during the same period, the concentration characteristics of VOCs were investigated. Emissions of VOCs were discussed by using PMF (positive matrix factorization) receptor model and CPF (conditional probability function). The Photochemical properties of ozone precursors on ozone formation were analyzed by using OZIPR (Ozone isopleths plotting package research).The averaged mixing ration of the TVOCs is about (40.85±29.68)x10-9per hour,49.43%of the TVOCs were alkanes,23.04%to alkenes,18.49%to aromatics and9.04%to acetylene. The composition of VOCs was not exactly at the same and it has not obvious seasonal variation. The diurnal variation shows a bimodal diurnal variation trend and the concentration value higher during night than day. The concentration of polluting gases such as NOx, SO2and CO was reduced during the Asian Youth Games. However, the mixing ration of VOCs was increased. Compared with the same period in2012, the ratio of alkanes and acetylene were reduced, olefins and aromatics increased in the total VOCs.Five sources were identified for summer major contributors to ambient VOCs concentrations by PMF.33.1%of the total VOCs were attributed to vehicle related emissions,25.8%to fuel evaporation,23.2%to industrial emissions,8.1%to solvent evaporation and9.7%to plant emissions. For alkanes, vehicle emissions, industrial emissions, fuel and solvent evaporation accounted respectively23.7%,35.3%,31.3%and2%. For alkenes, fuel evaporation for41.1%, industrial emissions for18.4%, vehicle emission for24.3%. Vehicle emission was the first contributor to aromatics, accounted for49.2%, secondly was solvent evaporation for30.8%.the result of CPF show that the distribution of emission source is mach with the result of PMF.VOCs are the dominant factor of ozone formation in the northern suburb of Nanjing. Initial concentration of ozone precursors plays an important role in the ozone formation. It is obviously that the contribution to the ozone for the emission of NOx than VOCs. Active species has much more influence to ozone than the other unreactive species does under the same condition, such as Alkenes, Trimethylbenzene, etc. Alkanes, toluene and xylene are belonging to the lower active species. It is more effective to reduce the active species of VOCs for avoiding the photochemical pollution in the city.