AGNES KERESZTESI, PETRES SANDOR, GINA GHITA, FLORINA DIANA DUMITRU, MIHAELA ANDREEA MONCEA, ALEXANDRU OZUNU, ROBERT SZEP AMMONIUM NEUTRALIZATION EFFECT ON RAINWATER CHEMISTRY IN THE BASINS OF THE EASTERN CARPATHIANS - ROMANIA A study of precipitation chemistry was conducted from 2006 January to 2016 November in the Ciuc and Giurgeu basin, Eastern Carpathians, Romania. The results show that the natural precipitation in these areas is alkaline, with a volume weighted mean (VWM) of 6.49 and 6.88 in Ciuc and Giurgeu basin, respectively. NH4+ is the most potential species to completely neutralize the rainwater over the Miercurea Ciuc (Ciuc basin) and Toplita (Giurgeu basin) area. However, in the case of Miercurea Ciuc, Ca2+ is also a potential neutralizer. Annual mean percentage concentration of NH4+ within the total principal cations is also proof that ammonium dominates the rainwater chemistry in the atmosphere of the studied basins. A comparison between the annual mean deposition fluxes showed that in the Giurgeu basin concentrations of NH4+ are higher than in the Ciuc basin. Calculations of the neutralization factors (NFs) show that at both sampling sites NH4+ contributed the most to the neutralization process. Ammonium availability index (AAI) has a value of 156.44% and 179.11% for Miercurea Ciuc and Toplia, respectively, indicating excess ammonium over the neutralization value. Fractional acidity (FA) was calculated, indicating that in Miercurea Ciuc 98.74% and in Toplita 99.28% of the rainwater acidity was neutralized. Calculation of the original and measured acidity also showed the neutralization capability of NH4+. Contributions of the marine and non-marine salts and enrichment factors were estimated, helping to identify the possible sources of the major ions in the atmosphere.
Keywords: ammonium neutralization effect, alkalinity, eutrophication, rainwater chemistry, ionic species