Volatile organic compounds speciation and their influence on ozone formation potential in an industrialized urban area in Brazil

摘要

Speciation and the influence on the ozone formation potential (OFP) from volatile organic compounds (VOCs) have been studied between February June 2013 in Vitoria, ES, Brazil. Passive samplers were installed at three air-quality monitoring stations and a total of 96 samplings were collected. A total of 78 VOCs were characterized by gas chromatograph-mass spectrometer. The predominant group was organic acids, followed by alcohols and substituted aromatics and 14 precursor species were quantified. An analysis correlating concentrations with wind direction was conducted to identify possible sources. The OFP was calculated applying the scale of maximum incremental reactivity proposed by Carter.[23] Ozone precursors with the greatest OFP such as undecane, toluene, ethylbenzene and m, p-xylene compounds were the most abundant with means of 0.855, 0.365, 0.259 and 0.289 mu g m(-3), respectively. The benzene, toluene, ethylbenzene and xylene (BTEX) group was found below the limits considered harmful to the health of the population living in Vitoria. The OFP calculated for the precursors group was 22.55 mu g m(-3) for the rainy season and 32.11 mu g m(-3) for the dry season. The VOC/NOx ratio in Vitoria is approximately 1.71, indicating that the region has a VOC-limiting condition for the production of ozone.