HR: 0800h
AN: B41D-0232    [Abstracts]
TI: The Possible Role of air Pollution in Dust-Fe Mobilization and its Implications to Global Carbon Cycle
AU: Chameides, W L
EM: BChameides@environmentaldefense.org
AF: Environmental Defense, 257 Park Avenue South , New York, NY 10010 United States
AU: * Meskhidze, N
EM: nmeskhidze@eas.gatech.edu
AF: Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332 United States
AU: Nenes, A
EM: nenes@eas.gatech.edu
AF: Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332 United States
AU: Nenes, A
EM: nenes@eas.gatech.edu
AF: Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332 United States
AU: Luo, C
EM: chaoluo@bren.ucsb.edu
AF: University of California, University of California, Santa Barbara, CA 93106 United States
AU: Mahowald, N
EM: mahowald@ucar.edu
AF: National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80307 United States
AB: For iron (Fe) contained in aeolian dust to act as a micronutrient for oceanic phytoplankton, some fraction of it must first be transformed (mobilized) into a form soluble in ocean water. Dust-Fe solubilization in deliquesced mineral aerosols can occur by the incorporation of SO2 into the advecting dust plumes and subsequent acidification of the dust through heterogeneous SO2 oxidation. The possible role of air pollution in dust-Fe mobilization are investigated in two contrasting studies conducted in: (i) subarctic North Pacific (where long-range advected Gobi-dust plumes travel over industrially developed cities of China and therefore have an ample opportunity to entrain high concentrations of anthropogenic air pollutants, i.e., SO2) and (ii) subantarctic South Atlantic (with dust plumes from Patagonia advected over sparsely populated pristine areas). Both regions of the ocean are known as high-nitrate low-chlorophyll (HNLC) areas where net primary productivity is limited by the availability of iron. In the first study, model simulations are carried out for documented Gobi-desert storms that advected mineral dust to Fe-limited regions of subarctic North Pacific. The estimated change in phytoplankton population inferred from the model-calculated inputs of bioavailable Fe is consistent with the satellite-measured chlorophyll a concentrations, suggesting that air pollution from China may actually affect net primary productivity and the associated uptake of atmospheric carbon dioxide in surface waters North Pacific Ocean. By extension, air pollution controls in China which lowered SO2 emissions might depress carbon uptake in these same waters. Contrasting North Pacific, model simulations for subantarctic South Atlantic suggest that the amount of SO2 available to be mixed with dust plumes from Patagonia is not high enough to acidify mineral dust and solubilize dust-Fe into bioavailable form. Analysis of remotely sensed sea surface temperature, ocean chlorophyll a content, sea level pressure and model-derived atmospheric dust-Fe fluxes revealed that surface ocean productivity in subantarctic South Atlantic is likely controlled by oceanic sources through upwelling of nutrient-rich waters from the deep ocean, continental margins and the island's shell. To the extent that biological activity in this region plays an important role in the contemporary global carbon cycle, this result suggests that changes in the dust-Fe supply, without significant increase in sulfur sources (i.e., from volcanic activities), may not exert considerable influence on the drawdown of atmospheric CO2 in South Atlantic Ocean.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 1030 Geochemical cycles (0330)
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
SC: Biogeosciences [B]
MN: Fall Meeting 2005