Title

Ferrous iron and hydrogen peroxide produced by marine aerosols deposited in ocean water of the Equatorial Pacific Ocean

Presenter Information

Hsiang Teng
Hoi Ting

Document Type

Oral Presentation

Location

SURC Ballroom C/D

Start Date

16-5-2013

End Date

16-5-2013

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 obtain. To further our understanding of reactions that transform iron after it is deposited into the ocean we performed photochemical experiments using 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. Fe(II) and H2O2 increased in the presence of light during the course of the dissolution experiments and spiked with the addition of dimethyl sulfide, which is a compound emitted by phytoplankton when under stress such as iron limitation. These results show that Fe(II), which is found to be more bioavailable than its oxidized 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.

Poster Number

51

Faculty Mentor(s)

Anne Johansen

Additional Mentoring Department

Chemistry

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Ferrous iron and hydrogen peroxide produced by marine aerosols deposited in ocean water of the Equatorial Pacific Ocean

SURC Ballroom C/D

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 obtain. To further our understanding of reactions that transform iron after it is deposited into the ocean we performed photochemical experiments using 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. Fe(II) and H2O2 increased in the presence of light during the course of the dissolution experiments and spiked with the addition of dimethyl sulfide, which is a compound emitted by phytoplankton when under stress such as iron limitation. These results show that Fe(II), which is found to be more bioavailable than its oxidized 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.