AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Ferrous Iron and Hydrogen Peroxide Produced by Marine Aerosols Deposited in Ocean Water of the Equatorial Pacific Ocean
HSIANG TENG, Hoi Ting, Dan Hinz, Anne Johansen, Central Washington Universtiy
Abstract Number: 711 Working Group: Remote and Regional Atmospheric Aerosols
Abstract The Equatorial Pacific Ocean is limited in primary productivity by the micronutrient iron, which is delivered to the ocean through the deposition of continental aerosols. Despite the fact that the amount and speciation of this iron controls phytoplankton productivity and thus has implications on the carbon cycle and global climate, accurate estimates of the atmospheric contribution of bioavailable iron to the surface ocean are difficult to attain. To further our understanding of reactions that transform iron after it is deposited into the ocean we performed photochemical experiments of real collected aerosol particles in real ocean water. Subnanomolar levels of ferrous iron (Fe(II)) and hydrogen peroxide (H2O2) were determined with chemiluminescence detection in the presence of luminol and acridinium ester, respectively. In general, Fe(II) and H2O2 increased in the presence of light during the course of the dissolution experiments. When extracts were spiked with small amounts of dimethyl sulfide or isoprene, which are compounds emitted by phytoplankton, Fe(II) production was enhanced. These results show that Fe(II), which is the more bioavailable form or iron compared to its oxidized and insoluble counterpart, is produced by compounds that are co-deposited with aerosol particles as well as compounds directly emitted by phytoplankton. These mechanisms of iron redox cycling in surface ocean waters allow us to better predict the impact of changing aerosol loadings on the carbon and sulfur cycles and global climate.