Inferring episodic atmospheric iron fluxes in the Western South Atlantic

Abstract

Iron (Fe) and other trace elements such as Zn, Mn, Ni and Cu are known as key-factors in marine biogeochemical cycles. It is believed that ocean primary productivity blooms in iron deficient regions can be triggered by iron in aeolian dust. Up to now, scarce aerosol elemental composition, based on measurements over sea at the Western South Atlantic (WSA), exist. An association between the Pata-gonian semi-desert dust/Fe and chlorophyll-a variability at the Argentinean continental shelf is essen-tially inferred from models. We present here experimental data of Fe enriched aerosols over the WSA between latitudes 22 Se62 S, during 4 oceanographic campaigns between 2002 and 2005. These data allowed inferring the atmospheric Fe flux onto different latitudinal bands which varied from 30.4 to 1688 nmolFe mÀ2 dayÀ1 (October 29 theNovember 15th, 2003); 5.83e1586 nmolFe mÀ2 dayÀ1 (February15theMarch 6th, 2004) and 4.73e586 nmolFe mÀ2 dayÀ1(October 21 steNovember 5th, 2005).