Halogens in aerosols in Central Alaska

Abstract

High volume filter samples were collected at Poker Flats in central Alaska, between 1984 and 1987, and analysed for a comprehensive suite of elements. In this report we focus on the results for the halogen elements Br, Cl and I, and their correlations with other selected elements (Al, As, Na, Se, and V). Seasonal cycles were observed for the halogens, including a pronounced spring peak in Br and a weak fall peak, pronounced spring and fall peaks in I, and increased winter/spring Cl. A significant correlation between Br and Se was shown to be partly due to common transport pathways, and possibly some common sources. Iodine showed enrichments of three orders of magnitude over sea water composition. Correlations to marine elements suggested a marine biogenic source. Chlorine evidently originated from sea salt aerosols, but showed evidence of substantial volatilization, correlated to the degree of pollution of the air mass.