Temporal Variation and Chemical Composition of Wet Atmospheric Deposition From Two Coastal Sites in the Gulf of Mexico

Wet atmospheric deposition (WAD) measurements during the cyclic warm and dry periods in San Francisco de Campeche City (CAM) and “La Mancha” (LM), Veracruz-Mexico are presented and compared. The behavior of the ionic species in WAD periods from 2006 and 2012 are described. Data on ion concentrations in WAD samples for the study period were analyzed to assess the effects of acid precipitation and to determine sources origin in these heritage cities. During the study the pH values averaged were 6.4 and 4.7 for CAM and LM, indicating active neutralization of the acidic species caused by the alkaline particles due to the high mineral content in the region, La Mancha site tends to be acidic, due to emissions related to fuels from oil platforms. The evaluation of SO₄²⁻/NO₃⁻ suggests emission sources with greater contribution of sulfur over nitrogen species and the formation of secondary compounds in both sites. Cluster Analysis (CA), showed for the Campeche site a strong correlation between Ca²⁺, K⁺, from soil origin; and SO₄²⁻, NO₃⁻, suggesting vehicular emissions, and NH₄⁺ associated with the burning of crop fields. The CA for “La Mancha” site showed that SO₄²⁻, Ca²⁺, Mg²⁺ is related to geological material, and a second group consisting of NH₄⁺, NO₃⁻ related to fuel emissions.