TY - JOUR
T1 - Atmospheric input of manganese and iron to the ocean
T2 - Seawater dissolution experiments with Saharan and North American dusts
AU - Mendez, Jeffrey
AU - Guieu, Cecile
AU - Adkins, Jess
N1 - Funding Information:
We would like to acknowledge Marith Reheis (USGS) for kindly providing the U.S. dust, Stéphane Moustier (CEREGE-France) for the grain-size distribution measurements, Kristen Buck (UC Santa Cruz) for the seawater ligand measurements, Diego Fernandez for his expertise with the ICP-mass spectrometer, and James Morgan for insightful discussions. This work was partly supported by the National Science Foundation (grant OCE-0502642), by the Comer Science and Education Foundation, and by the European FAIRY Program (Marie Curie Int. Fellowships — Contract MOIF-CT-2004-002918).
PY - 2010/6/20
Y1 - 2010/6/20
N2 - Dissolution of wind blown dust is a major source of iron, manganese and other trace nutrients in the ocean. Kinetic and thermodynamic values for the release of metals from dust are needed for computer models which incorporate dust as part of their ocean system. Here we investigate both the thermodynamic and kinetics parameters involved in the dissolution of metals from dust in seawater. We added dust from the Sahara and the Western United States in five different concentrations (0.01-5.0 mg/L) representative of those concentrations found in seawater after dust events, to open-ocean Pacific seawater. Sub-sampling of the reaction vessels took place on days 1, 2, 4, 7, 14, and 35 for the kinetic study. Results show different apparent thermodynamic constants for manganese (Mn) and iron (Fe). The final Mn concentrations are proportional to the added dust concentration. Fe concentrations reach a maximum of less than 2 nM, independent of the quantity and type of dust added. The Fe dissolution kinetics are faster than our sampling resolution. The first order rate constant for the dissolution of Mn from the Western US and Sahara dusts were 0.94 ± 0.04 frac(nmol Mn, day mg Dust), and 0.22 ± 0.01frac(nmol Mn, day mg Dust) respectively. We conclude that, Mn concentrations are limited by available Mn on the dust surface, while Fe concentrations are limited by the ligand concentrations in the seawater, which ultimately are determined by the biological community.
AB - Dissolution of wind blown dust is a major source of iron, manganese and other trace nutrients in the ocean. Kinetic and thermodynamic values for the release of metals from dust are needed for computer models which incorporate dust as part of their ocean system. Here we investigate both the thermodynamic and kinetics parameters involved in the dissolution of metals from dust in seawater. We added dust from the Sahara and the Western United States in five different concentrations (0.01-5.0 mg/L) representative of those concentrations found in seawater after dust events, to open-ocean Pacific seawater. Sub-sampling of the reaction vessels took place on days 1, 2, 4, 7, 14, and 35 for the kinetic study. Results show different apparent thermodynamic constants for manganese (Mn) and iron (Fe). The final Mn concentrations are proportional to the added dust concentration. Fe concentrations reach a maximum of less than 2 nM, independent of the quantity and type of dust added. The Fe dissolution kinetics are faster than our sampling resolution. The first order rate constant for the dissolution of Mn from the Western US and Sahara dusts were 0.94 ± 0.04 frac(nmol Mn, day mg Dust), and 0.22 ± 0.01frac(nmol Mn, day mg Dust) respectively. We conclude that, Mn concentrations are limited by available Mn on the dust surface, while Fe concentrations are limited by the ligand concentrations in the seawater, which ultimately are determined by the biological community.
KW - Aerosol
KW - Dust dissolution
KW - Iron
KW - Manganese
KW - Marine chemistry
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U2 - 10.1016/j.marchem.2008.08.006
DO - 10.1016/j.marchem.2008.08.006
M3 - Article
AN - SCOPUS:77953139607
SN - 0304-4203
VL - 120
SP - 34
EP - 43
JO - Marine Chemistry
JF - Marine Chemistry
IS - 1-4
ER -