Chemical composition of precipitation in a Mexican Maya region

The chemical characteristics of wet precipitation in Puerto Morelos, Quinta na Roo State, Mexico, were measured From April 1994 to December 1995, Puert o Morelos is located in the Caribbean Mayan coastal region of the Peninsula of Yucatan, and is normally exposed to winds from the Caribbean region. We tfall was analyzed for pH, conductivity and Cl-, NO-3, SO42-, Na+, NH4+, K, Mg2+ and Ca2+ ion concentrations. Volume-weighted mean pH for the whole s ampling period was 5.35, although values as low as 4.6 were measured in sev eral rain samples. Concentrations of all species correlated negatively with rain volume. Sea-salt aerosols contributed with most of the Na+, Cl-, Mg2, K+ and SO42- found in wet precipitation. The mean [SO4excess2-] was 9.7 m u Eq 1(-1), which agrees with the background hemispheric Values of approxim ate to 10 mu Eq 1(-1) reported elsewhere. The mean [NO3-]; was 11.4 mu Eq 1 (-1), almost four times higher than the background hemispheric value of app roximate to 2.5 mu Eq 1(-1) reported elsewhere. However, a major component causing the slight acidity character of rain in Puerto Morelos seems to be H2SO4. (C) 2000 Elsevier Science Ltd. All rights reserved.