Collaborative Research: Influences of Atmospheric Deposition, Organic Complexation and Photochemical Processes on the Redox Cycle of Iron in Surface Waters

在高营养、低叶绿素的地区，浮游植物的生产力受到铁的生物利用度的限制。 海洋微生物对铁的吸收似乎受到溶解态铁的氧化还原和溶液形态的强烈影响，但人们对影响海洋中铁化学和生物利用度的物理化学过程，如光化学还原、胶体形成和有机络合作用知之甚少。 为此，主要研究人员建议开展一系列面向过程的研究，以调查（1）墨西哥湾（GOM）上部100米处Fe的昼夜光化学和热化学氧化还原循环;（2）水提铁的氧化还原形态（降雨）和干（气溶胶）沉降，以及沉降后最初几小时内发生的物理化学变化;和（3）Fe（III）被开放贫营养GOM中的胶体和低分子量溶解有机配体络合和潜在还原，并且包括来自天然硅藻水华、有害藻类（甲藻）水华和来自陆地水生有机配体的河流输入的配体。 预计这项研究的结果将进一步我们的非生物，无机过程调节铁的分布和形态的理解，以及提供所需的数据，模拟海洋铁循环。

ABSTRACTOCE-9911339OCE-0000351Phytoplankton productivity in high nutrient, low chlorophyll areas is limited by the bioavailability of iron. Iron uptake by marine microorganisms appears to be strongly influenced by the redox and solution speciation of dissolved Fe, yet very little is known about the physical-chemical processes such as photochemical reduction, colloid formation, and organic complexation that affect Fe chemistry and bioavailability in the oceans. For this reason, the principal investigators propose to undertake a set of process-oriented studies to investigate (1) the diel photochemical and thermochemical redox cycling of Fe in the upper 100 meters of the Gulf of Mexico (GOM); (2) the redox speciation of dissolved Fe supplied by wet (rainfall) and dry (aerosol) deposition, and the physical-chemical transformations that occur within the first few hours following deposition; and (3) the complexation and potential reduction of Fe(III) by colloidal and low molecular weight dissolved organic ligands in the open oligotrophic GOM, and including ligands from natural diatom blooms, harmful algae (dinoflagellate) blooms, and from riverine input of terrestrial aquatic organic ligands. It is expected that results from this study will further our understanding of the abiotic, inorganic processes regulating the distribution and speciation of Fe, as well as provide data required to model oceanic Fe cycling.