Influence of peat fires on the rainwater chemistry in intra-mountain basins with specific atmospheric circulations (Eastern Carpathians, Romania).

A comprehensive study on the chemical composition of precipitation, the influence of peat fires and their relations with atmospheric circulation was conducted in the year of 2012, in two intra-mountain basins, the Ciuc basin (CB) and the Giurgeu basin (GB), Eastern Carpathians, Romania. Atmospheric circulation types showed the presence of a westerly anticyclonic circulation, characterized by a strong development of the Azores High to the northern Atlantic, contributing to the appearance of peat-fires. Using ROCADA daily gridded climatic datasets, the maximum and minimum daily temperatures were extracted, showing deviation from 2 °C to 6 °C in the studied year against the multiannual mean for the 1981-2016 period. Rainwater samples were analyzed for pH, major anions and cations; HCO3- concentrations were calculated based on the empirical relationship between pH and HCO3-. The results showed that 45.16% and 54.55% of precipitation had pH > 7.0 at CB and GB, respectively. NH3, NH4+ and Ca2+ are the main neutralizing agents. The significant correlation between SO42- and NH4+ (r = 0.711 - CB; r = 0.736 - GB) indicated neutralization by NH3 in the forms of (NH4)2SO4 and NH4HSO4. Positive regression coefficient between the sum of (H+ + [NH4+] + [Ca2+]) and the sum of ([nss - SO42-] + [NO3-]) (r = 0.855 - CB; r = 0.796 - GB), showed that acid neutralization was primarily brought by NH4+ and/or CaCO3. Using Na as an indicator of marine origin, the proportions of sea salt and non-sea-salt were estimated from elemental ratios. According to correlation analysis and PCA, main acidic ions (SO42- and NO3-) and NH4+ were mainly derived from anthropogenic activities (biomass burning, peat fires, fertilization), while Ca2+ and Mg2+ originated from terrestrial sources. The behavior of gaseous pollutants and smoke distribution resulted from peat fires were deciphered using the HYSPLIT model in a case study.