Seasonality Influence in the Distribution of Formic and Acetic Acids in the Urban Atmosphere of São Paulo City, Brazil

Abstract

Níveis ambientais diurnos de ácido fórmico e acético foram medidos na atmosfera da cidade de São Paulo no inverno e na primavera de 1996. Foi feita uma comparação das concentrações dos ácidos carboxílicos entre dois sítios urbanos distintos. Os resultados demonstraram que os níveis de ácidos carboxílicos foram afetados pela variação sazonal no sítio com contribuição alta de emissão veicular enquanto que no outro sítio estudado não foi observada esta influência. As concentrações variaram de 0,64 a 11,8 ppbv para ácido fórmico e 0,51 a 10,7 ppbv para ácido acético. Os dados obtidos foram discutidos em relação à emissão direta e a produção fotoquímica in situ.Ambient levels and diurnal profiles of formic and acetic acids were measured in the atmosphere of São Paulo City in winter and spring 1996. A comparison between two different urban sites was done. Results demonstrate that carboxylic acid levels were affected by seasonality in the site with high vehicular emission density, while no seasonal influence was observed for the other site studied. Ranges of mixing ratios from 0.64 to 11.8 ppbv for formic acid and 0.51 to 10.7 ppbv for acetic acid were recorded. The results concerning the carboxylic acid concentrations were discussed with respect to direct emission and in situ photochemical production.

Disentangling vehicular emission impact on urban air pollution using ethanol as a tracer

“…Nonetheless, given the high abundance of this species in downtown Sao Paulo 20 , the relatively low sensitivity does not affect data quality. Furthermore, formic acid concentrations measured at a Sao Paulo downtown site under similar meteorological conditions several years prior our field campaign yielded a formic acid concentration of 2.6 ppb 58 (about only 10% of estimated ethanol concentration here). Considering a comparable concentration at the time of the campaign, it does not impact ethanol concentration estimates significantly, and much less undermines the identification of the LDV-OA factor.…”

Short-term leaf responses of Nicotiana tabacum 'Bel-W3' to ozone under the environmental conditions of São Paulo, SE - Brazil

“…The dynamic chemistry of ozone and of other secondary photochemical pollutants in the atmosphere of São Paulo is partially attributed to the use of hydrated ethanol and gasohol as motor fuel, which directly reduces the emissions of carbon monoxide and non-methane volatile organic compounds but promotes increases in atmospheric concentrations of nitrogen oxide and aldehyde. Consequently, enhanced levels of O 3 , PAN, organic acids and other photochemical compounds are expected (Tanner, 1998;Campos et al, 1999;Souza and Carvalho, 2001;Montero, et al, 2002;Muramoto et al, 2003). In such particular situation, the plants of N. tabacum 'Bel-W3' showed not to react closely to daily ozone concentrations, although this cultivar has been highly standardized for assessing the biological risks of this pollutant (Heggestad, 1991;VDI 2000VDI , 2003.…”

“…This site can be considered potentially impacted by different types of pollution sources. The precursors of the ozone in the region seem to come predominantly from biogenic emissions from the fragment of forest protected by the State Park and from vehicular emissions (Souza and Carvalho, 2001;Montero et al, 2002). In the springtime, from 16 September to 14 October 2002, air sampling and tobacco Bel-W3 exposures were done.…”

HS-SPME Determination of Volatile Carbonyl and Carboxylic Compounds in Different Matrices

“…The most common analytical procedures for carboxylic acids in air and car exhaust include a sampling step with either liquid (potassium hydroxide or calcium hydroxide aqueous solutions) or solid traps (2,(13)(14)(15)(16)(17). Quartz, glass wool, or cellulose are typical supports used in the latter type of traps to embed potassium hydroxide, sodium carbonate, or calcium hydroxide.…”

“…Potassiumimpregnated silica gel-C 18 cartridges have been employed as well (18,19). These sampling approaches have been combined with various instrumental techniques, such as ion chromatography, liquid chromatography, capillary electrophoresis, and GC (13)(14)(15)(16)(17)(18)(19). However, low selectivity, low sensitivity, and long analysis times are common to these procedures.…”