Identification of ion sources in rainwater of a coastal site impacted by the gas and oil industry in the southeast of Mexico

Abstract

The purpose of this research was to study the chemical composition of rainwater to assess the impact of marine aerosol and anthropogenic emissions by using back air-mass trajectories. Fieldwork was done from July to November 2004, in a coastal site probably impacted by gas and oil industry in Campeche, Mexico: San Antonio Cardenas. Na+, Cl-, and Mg 2+, were the most abundant ions, being sea-salt aerosol their unique source. A significant portion of K+ and Ca2+ originated from non-sea-salt sources; and the sulphate excess exceeded the background level reported for remote marine sites, suggesting that besides of marine aerosol, there was a significant contribution of SO42- from anthropogenic sources. NO3- concentrations in San Antonio Cardenas exceeded the background level reported for coastal sites with minimal anthropogenic influence and showed a significant correlation with SO 42-, suggesting a common source. Agricultural practices are null, for this reason NH4+ levels were low. Mean pH value was 4.64, this acidity showed a good correlation with SO42- and NO3- levels, and with the local meteorology. A sour gas recompression plant located 10 km at NE from San Antonio Cardenas was identified as the main source of this strong acidity. Copyright © 2008 Global NEST.