Metalloids in Wet Deposition on Bermuda: Concentrations, Sources, and Fluxes

Abstract

The concentrations of antimony, arsenic, and selenium were determined in wet deposition samples collected on a daily (event) basis from 1988 to 1990 on Bermuda as a part of the Atmosphere/Ocean Chemistry Experiment (AEROCE). Isentropic back trajectories were used to identify air masses that passed over North America (59% of the events), Europe or North Africa (8%), or were largely marine in origin (33% of the events). The North American trajectories had the highest volume-weighted average (VWA) concentrations and crustal enrichment factors for the three metalloids; the As/Se ratio and good correlations with acidity suggest inputs from fossil fuel combustion. The Euro-African trajectories had the lowest VWA concentrations and enrichment factors that approached crustal values, indicating mineral aerosol inputs; values for marine events fell between these two extremes. The atmospheric flux of metalloids to the western Atlantic Ocean represents a major source of these elements in surface waters (up to 100% for Sb and Se; up to 61% for As) and a corresponding sink in their global atmospheric budgets