Chemical characteristics and source apportionment on ionic composition of rainwater in the Romanian Carpathians, Europe, and Conterminous United States

Abstract

The thesis is a complex study of precipitation chemistry using methods and models of environmental chemistry and geochemistry. Its elaboration started from the validation of some mathematical models, and by analyzing the dispersion behavior of some chemical species in atmospheric precipitation samples collected in closed intramountain basins. These closed basins are characterized by the specific microclimate conditions, which helps to develop the models mentioned above. In the intramountain depressions studied in the Eastern and Southwestern Carpathians, the influence of the Carpathian arc can be observed on the continental and/or oceanic air masses, and on the specific local characteristics, respectively. By analyzing the chemical composition of precipitation corroborated with the air masses circulation, significant modifications can be observed due to climate change that is present both at local level (by the appearance of local anticyclonic systems) and at continental level, by changing the trajectory of continental air masses. These changes are visible by the long-range transport of some chemical species present in different regions. The concentration of sea salts, respectively the significant specific correlation between chloride and sodium or its loss in certain regions are indicators of the changes occurred in the air masses. The Foehn effect of the Dinaric Alps on the chemical composition of atmospheric precipitation has been highlighted. By extrapolating the results obtained in intramountain depressions to the European level, corroborating them with the climate policies assumed in the last two decades by the European Union member states indicates a homogenization and an accentuated decrease of acid ions, in comparison to non-EU countries, where higher levels of acidic pollutants were observed. The calculation techniques used at European level were extrapolated to the contiguous United States, which in comparison to the European continent, has a much greater climate variability, and the applied environmental policies are not unitary, hence there is a clear trend of less visible decrease of different pollutants compared to EU countries.