Chemical composition and seasonal variation of acid deposition in Chiang Mai, Thailand.Sillapapiromsuk, S. and Chantara, S
Environmental Engineering Research, 15: 93-98.
This study aims to determine the chemical composition and seasonal variation of atmospheric acid deposition in order to identify possible sources contributing to precipitation. Sampling and analysis of 132 wet deposition samples were carried out from January to December 2008 at Mae Hia Research Center, Chiang Mai University, Chiang Mai Province. Total precipitation was 1,286.7 mm. Mean electro-conductivity and pH values were 0.94 mS/m and 6.27, respectively. Major cations (Na^+, NH4^+, K^+, Ca^2+, and Mg^2+) and major anions (HCOO^-, CH3COO^-, Cl^-, NO3^-, and SO4^2-) were determined by Ion Chromatography. The relative volume weight mean concentrations of anions, in descending order, were SO4^2- > NO3^- > Cl^- > CH3COO^- > HCOO^- and those of cations were NH4^+ > Ca^2+ > Mg^2+ > K^+ >Na^+. Results of a principle component analysis highlighted the influence of various possible sources of ions such as agricultural activity, fuel combustion, marine sources, soil resuspension, and biomass burning.