Inorganic and Organic Acids in the Atmosphere of the Urban Area of the City of Salvador, Brazil

Lícia Cruz,Franciele Santana,Sâmeque Luz,Elisvan Mota,Vânia Campos,Daniela Santos

doi:10.21577/0103-5053.20180227

Lícia Cruz, Franciele Santana + Show 4 more

Open Access

https://doi.org/10.21577/0103-5053.20180227

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Abstract

Different fuels are used in Brazil and there is little knowledge about the presence of organic and inorganic acids in the atmosphere of the Brazilian cities. HNO3, HCl, HCOOH and CH3COOH were sampled in the gas phase using passive samplers and thermodiffusion system, in which the H2SO4 particulate was also sampled, in five sites of Salvador. Ion chromatography analyses showed that the organic and inorganic acids measured contributed on average with 89 and 11%, respectively, to the acidity of the city’s atmosphere. The strong correlations between HCOOH, CH3COOH and HCl with CO and NO2 indicated a common source for these compounds, predominantly from vehicular emissions. H2SO4 showed strong correlations with PM10 (particulate matter 10 µm or less in diameter) and with its precursor SO2; and HNO3 with NO2 and NO precursors. Most of the compounds presented negative correlations with meteorological parameters. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) confirmed these observations. The ratios [HCOOH] / [CH3COOH] varied between 0.69-1.9, typical of urban areas.

Highlights

Air pollution has been considered the main environmental degradation agent of the planet
Considering the five acids measured in this study, it was estimated that the two organic acids contributed, on average, to 89% of the acidity of the city’s atmosphere
The results found for the ratios of the formic and acetic acids concentrations (F/A) are presented in Table 3 and they were used to suggest the origin of these acids in the atmosphere of the city of Salvador

Summary

Introduction

Air pollution has been considered the main environmental degradation agent of the planet. The major air pollution problems arise from the release of gases and particles into the atmosphere, and the main sources are vehicles and industrial activities. The magnitude of the impact on air quality depends on the prevailing weather conditions, which is responsible for the transportation, transformation and dispersion of the emitted pollutants, as well as the possible occurrence of critical situations of air pollution. The action of pollutants is further aggravated when weather conditions are unfavorable to their dispersion in the atmosphere.[1,2]. One of the most subtle problems related to the air quality degradation is the presence of acids in the atmosphere, which can be transported and deposited by dry or wet processes, mainly by rain, producing one of the most well-known phenomena in terms of atmospheric pollution: acid rain. The studies only considered the inorganic acids (sulfuric, nitric and hydrochloric acids) and their precursors (sulfur dioxide and nitrogen oxides)

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