Sulfate and nitrate in wet atmospheric deposition on the coast of the Gulf of Mexico from 2003 to 2015

Rodolfo E. Sosa, Humberto A. Bravo, Ana Luisa J. Alarcón, B. María Del Carmen Torres, Pablo A. Sánchez, Mónica P. Jaimes, Elías H. Granados, David Gay

Research output: Contribution to journalConference article

Abstract

The Gulf of Mexico Region has important sources of acid rain precursors, both on land and at sea located in countries like USA, Mexico and Cuba, so it is very important to study the chemical composition of the wet atmospheric deposition through international cooperation. For many years along the coast of the United States, acidic precipitation values have been measured. Studies on the Mexican coast have recorded the presence of acid rain since 2003. In relation to acid rain, pH determination is essential, in addition to the composition of sulfate and nitrate that are formed from its main precursors, sulfur dioxide and nitrogen oxides, respectively. The aim of this study was to evaluate pH, sulfate and nitrate concentrations in wet atmospheric deposition, collected daily from 2003 to 2015 in a sampling site located along the coast of Mexico (La Mancha) and compare the values with the National Atmospheric Deposition Program (NADP) sampling sites located along the coast of the Gulf of Mexico from Texas to Florida. The HYSPLIT back trajectory model was applied in order to identify the emission sources of acid rain precursors. Trajectories showed an important transport to the sampling site from the East during the rainy season (June-October). The region located east to "La Mancha" is the Gulf of Mexico representing offshore operations for the exploration and production of petroleum. The annual VWM pH in wet deposition at "La Mancha" sampling site was in the range of 4.81 to 5.40 during the study period (2003-2015). For the year 2015, the pH was 5.22, which is similar for the USA sites. Additionally, the annual VWM concentration of SO42- was in the range of 15 to 31 μeq/L, and for the last year was 26.87 μeq/L, which is similar than the higher level registered in the USA (TX03 site); the annual VWM concentration of NO3- was in the range of 3.5 to 15 μeq/L and for 2015 was 5.48 μeq/L, which is lower than in the USA sites. The ratio SO42-/NO3- found for the site in Mexico in 2015 was 4.90, being the highest value compared to other sites on the coast of the Gulf of Mexico whose ratios were between 1.03 and 2.38. Therefore, it is important to consider the sulfur dioxide emission sources in Mexico. It is also recommended to extend the atmospheric deposition sampling to other sites in the Gulf of Mexico, like Mexico and Cuba.

Keywords

  • Acid rain
  • Atmospheric deposition
  • Gulf of Mexico
  • Nitrate
  • Sulfate

ASJC Scopus subject areas

  • Environmental Science(all)
  • Energy(all)

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    Sosa, R. E., Bravo, H. A., Alarcón, A. L. J., Del Carmen Torres, B. M., Sánchez, P. A., Jaimes, M. P., Granados, E. H., & Gay, D. (2017). Sulfate and nitrate in wet atmospheric deposition on the coast of the Gulf of Mexico from 2003 to 2015. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA.