Constraining the Solubility of Aerosol Fe using US GEOTRACES Data

Ana M Aguilar-Islas, University of Alaska Fairbanks, College of Fisheries and Ocean Sciences, Fairbanks, AK, United States, Clifton S Buck, Skidaway Institute of Oceanography, Savannah, GA, United States, Robert Rember, University of Alaska Fairbanks, Fairbanks, AK, United States and William M Landing, Florida State University, Earth, Ocean, and Atmospheric Science, Tallahassee, FL, United States
Abstract:
Atmospheric deposition represents an important input of micronutrients to surface waters, and is of particular interest as an input for the limiting micronutrient iron. The solubility of aerosol iron after deposition is not well constrained, and it has been shown to vary principally with aerosol composition, although dissolution methodologies also contribute to the observed variability. To address procedural artifacts and arrive at a better constrained estimate of aerosol iron fractional solubility, a flow-through on-board protocol designed to minimize experimental artifacts and to simulate conditions experienced by deposited aerosols was used during the US Atlantic GEOTRACES cruises and compared to laboratory leaching methods. Here we present results of the fractional solubility of aerosol iron obtained during the US GEOTRACES Atlantic and Pacific cruises, and suggest revising estimates for this parameter. Our data provides a more constrained upwardly adjusted estimate in the range of 8% to 14% solubility for iron in aerosols dominated by lithogenic sources, and a fractional solubility of 15% to 25% for iron in aerosols from air masses impacted by anthropogenic sources. Greater variability (6% to 55%) was observed in the solubility of iron in aerosols from maritime air masses.
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