Sources, Ionic Composition and Acidic Properties of Bulk and Wet Atmospheric Deposition in the Eastern Middle Adriatic Region

Abstract

Atmospheric bulk and wet deposition samples were collected simultaneously at the background coastal site in the Eastern Middle Adriatic region in order to assess the impact of major ions (Cl−, NO3−, SO42−, Na+, K+, NH4+, Mg2+, Ca2+) on deposition acidity and distinguish the main sources. Higher ion levels were observed during the cold period, especially for Cl−, Na+, Mg2+ and K+. Dust intrusion caused significant increases in levels of Ca2+, Mg2+ and K+, while open-fire events increased the levels of K+. Deposition acidity showed seasonal differences as well as the influence of dust intrusion. Low ionic balance ratios indicated acidic deposition properties and the presence of organic anions. The highest neutralization ability was found for Ca2+, Na+ and NH4+. Several natural (marine, crustal) and anthropogenic sources were determined, as well as the formation of secondary aerosols. Wet deposition was characterized by higher contribution of sea salt fraction compared to bulk deposition and lower contribution of crustal fraction.