Solubility and speciation of iron present on wind-borne dust and volcanic ash exported from sousthern South America

L. SIMONELLA, MIRIAM E. PALOMEQUE, G. ROMAN ROS, E LEGARRA SAEZ, J.A. SANS TRESERRAS Y D. GAIERO

Santa Rosa de la Pampa

Conferencia; ICAR VII, Internacional Conference on Aeolian Research; 2010

INTA-UNIVERSIDAD NACIONAL DE LA PAMPA

Is the amount and quality of iron (Fe) present in Southern South America (SSA) dust able to control past and present biological processes of the Southern Ocean (SO)? During the recent decade a great deal of effort has been devoted to establish the effects of mineral dust on global, as well as on regional climate. In this sense, it is recognized that wind-blown dust has the potential to significantly influence the biological activity in the oceans (the “iron hypothesis”) and to influence the regional climate by blacking sunlight and change cloud properties (radiative forcing effect). SSA is now recognized as an important dust supplier especially during cold periods. Then, the availability of iron (Fe) transported in SSA dust may control net primary productivity in high-nitrate low-chlorophyll (HNLC) regions such as the SO. However, little is known about the solubility and speciation of Fe on these materials and most of our knowledge is based on model simulations. Presently, top soils and dust from the arid diagonal of SSA and volcanic ash from Hudson (1991) and Chaitén (2009) eruptions are being characterizing in term of chemical and mineralogical composition in three different grain-size fractions (