Large portions of the world ocean are less productive than they should be based on their nutrient concentrations. Dubbed high-nutrient low-chlorophyll (HNLC) regions, primary productivity in these areas may be limited by any number of factors including high zooplankton grazing rates as well as light and silicon limitation but, in general, iron (Fe) appears to most often be the factor limiting production. With approximately 30% of the world ocean comprised of Fe-limited HNLC waters, it is clear that the input of Fe to these waters, and its subsequent bioavailability, has an important role in stimulating primary productivity and lowering pCO2 possibly moderating the rise of atmospheric CO2 concentrations and therefore could influence the planet's climate. The work described in this dissertation represents an effort to characterize the elemental solubility, including Fe, of marine aerosols. The research was conducted on four oceanographic research cruises in the North Atlantic and Pacific Oceans. In total, over 170 aerosol samples were collected in both total and size-fractionated samples. Precipitation events were sampled when possible to characterize the wet deposition of marine aerosols. The data will constrain estimates of aerosol Fe deposition to HNLC regions and improve models of the global carbon cycle. Elemental solubilities were measured using both seawater and ultrapure deionized water leaching methods under trace metal clean conditions. Leaching of the aerosol samples was conducted using a rapid exposure, small volume technique. Ultrapure deionized water leaches were analyzed directly by high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS), a relatively simple analysis technique. Soluble Fe in seawater leaches was analyzed by HR-ICP-MS following column extraction. Additionally, soluble aerosol Fe(II) was measured on four of the cruises. The sampling and analytical methods will be discussed in this dissertation and the results compared with similar studies of aerosol chemistry. The relationship between seawater and deionized water leaching was investigated to evaluate the applicability of the relatively simple ultrapure water technique to prediction of aerosol solubility in seawater. Elemental solubility behavior was analyzed within the context of a host of potential controlling factors including aerosol acidity, source region, and elemental composition among others. The results from these research cruises suggest that aerosol Fe solubility is relatively consistent globally. The solubility of aerosol Fe in deionized water was calculated to be ~12% and ~9% in filtered surface seawater. Aerosol Fe solubility percentage showed no significant correlation with the concentration of acidic aerosol species. The episodic nature of dust events was apparent from the highly variable measured concentrations of aerosol material and no apparent first order relationship existed between the concentration of crustal aerosol species (i.e. Fe) and their respective concentrations in the surface ocean. A robust relationship was found between the concentrations of the ultrapure deionized water and seawater soluble aerosol Fe and a predictive power law equation was derived. / A Dissertation submitted to the Department of Oceanography in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester, 2008. / June 4, 2008. / Aerosol Solubility, Mineral Dust, Atlantic Ocean, Pacific Ocean, Aluminum, Iron / Includes bibliographical references. / William M. Landing, Professor Directing Dissertation; Henry Fuelberg, Outside Committee Member; William Burnett, Committee Member; Joel Kostka, Committee Member; Thorsten Dittmar, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_181111 |
| Contributors | Buck, Clifton Stryker, 1978- (authoraut), Landing, William M. (professor directing dissertation), Fuelberg, Henry (outside committee member), Burnett, William (committee member), Kostka, Joel (committee member), Dittmar, Thorsten (committee member), Department of Earth, Ocean and Atmospheric Sciences (degree granting department), Florida State University (degree granting institution) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource, computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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