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 identity 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.