HR: 14:40h
AN: A22D-05    [PDF]
TI: The Role of Dimethyl Sulfoxide in the Reductive Dissolution of Iron in Marine Aerosols
AU: * Key, J M
EM: KeyJe@cwu.edu
AF: Central Washington University, Chemistry, 400 East University Way, Ellensburg, WA 98926 United States
AU: Johansen, A M
EM: Johansea@cwu.edu
AF: Central Washington University, Chemistry, 400 East University Way, Ellensburg, WA 98926 United States
AB: Very little is known about the effects of atmospheric iron (Fe) deposition from aeolian dusts into the remote oceans and the role it plays as a key nutrient for photosynthesis in marine phytoplankton in high nutrient low chlorophyll (HNLC) waters. Several in situ iron fertilization studies in HNLC regions have reported increases in chlorophyll a concentrations, nutrient and carbon uptake, and the release of various biogenic gases which have the potential to directly and indirectly impact global climate. Of particular interest in the present study is the indirect effect of dimethyl sulfoxide (DMSO) as part of a positive feedback cycle that may exist between such biogenically derived reduced sulfur compounds and crustal derived iron in the atmosphere over remote oceanic regions. To determine whether DMSO can lead to larger atmospheric concentrations of bioavailable iron in the form of Fe(II), photochemical simulation experiments were carried out using synthetic ferrihydrite (Fe5HO8$\cdot$4H2O) in the presence of DMSO. During these experiments DMSO oxidation products, such as methane sulfonic acid (MSA), methane sulfinic acid (MSIA), and sulfate (SO42-), were quantified by means of ion chromatography (IC), while Fe(II) was determined spectrophotometrically by complexation with ferrozine. Preliminary results suggest that current ambient DMSO levels are too low to play a significant role in the reductive dissolution of iron hydroxide in aerosol particles. However, increased DMSO levels may enhance bioavailability of iron, thus potentially closing the gap in the positive feedback cycle.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0365 Troposphere--composition and chemistry
DE: 4801 Aerosols (0305)
DE: 4852 Photochemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting