Characterization of Finnish arctic aerosols and receptor modeling

Abstract

Lower atmospheric aerosols have been characterized for the period of 1964-1978 in the European sub Arctic region at Kevo, northern Finland. A total of 685 weekly samples were analyzed for Ag, Al, As, Br, Ca, Cl, Co, Cu, I, In, K, Mn, Na, Sb, Si, Sn, Ti, V, W, and Zn using neutron activation analysis. Study of time series concentration levels, box plots of the monthly subsets, and the descriptive statistics of seasonal datasets showed that seasonal weather had less influence in the lower atmospheric elemental concentration levels at Kevo. Two very distinct silver concentration level periods, high and low, were observed in the Kevo atmosphere during 1964-1970 and 1971-1978. A comparison of anthropogenic elemental concentration levels in the Kevo lower atmosphere were found in the same range or 2-8 fold higher than reported literature data of Russian and Canadian Arctic during winter and spring seasons. Elements like In, Cu, Zn, As, Sb, Sn, and Ag were highly enriched in the Kevo lower atmosphere. Principal component factor analysis showed a strong smelting factor consisting of copper, zinc, indium, and tin. This factor was found to be more important in the principal component factor analysis (PCFA) in winter dataset than that of summer. A crustal factor was easily recognized in the winter PCFA results, but crustal components were mixed up with industrial components in the summer results. Sea source components appeared in a single factor in the summer PCFA results but were found in pairs into several factors in winter results. Antimony was mostly found in a single factor. The Unmix model was used to identify sources and source composition in the Kevo atmosphere. Residence time analysis was used for identifying the source location of all elements using an air parcel back trajectory ensemble. The impact of this research is three fold. First, it’s contribution to the ongoing Arctic research. Second, the modeling experience obtained from this very large dataset could be used for future research and monitoring. Third, the development of new NAA methodologies for determining important industrial marker elements, like silver and cobalt, and the development of a new scheme for cost-effective determination of medium lived isotopes.