Revisiting atmospheric dust export to the Southern Hemisphere ocean: Biogeochemical implications

Abstract

Aerosol concentrations in the Southern Hemisphere are largely undersampled. This study presents a chemical and physical description of dust particles collected on board research vessels in the southeast Pacific (SEPS) and the Southern Ocean (SOKS). Concentrations of dust were 6.1 ± 2.4 ng m −3 for SEPS and 13.0 ± 6.3 ng m −3 for SOKS. Dust fluxes, derived from those concentrations, were 9.9 ± 3.7 μ g m −2 d −1 for SEPS and 38 ± 14 μ g m −2 d −1 for SOKS and are shown to be representative of actual fluxes in those areas. Dust and iron deposition are up to 2 orders of magnitude lower than former predictions. A map of dust deposition on the Southern Hemisphere is proposed by incorporating those in situ measurements into a dust model. This study confirms that dust deposition is not the dominant source of iron to the large high‐nutrient low‐chlorophyll Southern Ocean.