Evaluation of the chemical composition of hailstones from triple border Paraná, Santa Catarina (Brazil) and Argentina

Abstract

The concentration of ions, metals, and metalloids in hailstone samples was evaluated for the first time in South America. The samples were previously cleaned with ultrapure water to eliminate potential contaminants. The ions concentrations in the samples showed a general pattern according to the following sequence: Ca2+ >NO3-> K+ > CHOO− > Mg2+ > Cl− >SO 42_> Na+ >NH4+ > F−. Regarding the metals and metalloids concentrations, the order was of Zn > Al > Fe > Mn > Sr > Ba > Cu > Ni > Cr > Pb > Co > V. Ca2+ was the most abundant and agricultural activity, one of the sources due to long-distance transport. Concentrations of K+ and Cl− may originate from fires that occur every year in the North and Center-West regions of Brazil. Local sources also contributed to the chemical composition, such as soil resuspension contributing mainly to the species and elements Al, Fe, Na+, K+, SO 42_, and F−. Besides that, the region is an agricultural area with unpaved roads and use of fertilizer; therefore, the species and elements NH4+, Mg2+, K+, Cl−, Cu, and Zn, were also associated with local sources, including emissions from vegetation. A possible vehicular contribution was also observed. Among the few existing studies, this is the first to evaluate the hailstones cleaning procedure's efficiency. The findings also support the previous studies' conclusion that the concentration of chemical species varies considerably according to the region of study's characteristics. This work contributes to improve the understanding of local and remote natural and anthropic emissions in this complex atmospheric phenomenon.