http://www.jlakes.org/news/hal-200812-sdarticle.pdf

Eutrophication and harmful algal blooms: A scientific consensus

Chemistry and biology of siderophores.

Chemistry of iron sulfides.

Marine dissolved organic matter (DOM) is a complex mixture of molecules found throughout the world's oceans. It plays a key role in the export, distribution, and sequestration of carbon in the oceanic water column, posited to be a source of atmospheric climate regulation. Biogeochemistry of Marine Dissolved Organic Matter, Second Edition, focuses on the chemical constituents of DOM and its biogeochemical, biological, and ecological significance in the global ocean, and provides a single, unique source for the references, information, and informed judgments of the community of marine biogeochemists. Presented by some of the world's leading scientists, this revised edition reports on the major advances in this area and includes new chapters covering the role of DOM in ancient ocean carbon cycles, the long term stability of marine DOM, the biophysical dynamics of DOM, fluvial DOM qualities and fate, and the Mediterranean Sea. Biogeochemistry of Marine Dissolved Organic Matter, Second Edition, is an extremely useful resource that helps people interested in the largest pool of active carbon on the planet (DOC) get a firm grounding on the general paradigms and many of the relevant references on this topic. * Features up-to-date knowledge of DOM, including five new chapters* The only published work to synthesize recent research on dissolved organic carbon in the Mediterranean Sea* Includes chapters that address inputs from freshwater terrestrial DOM

Biogeochemistry of marine dissolved organic matter

Few of us may ever live on the seaor under it, but all of us are mak-ing increasing use of it either as asource of food and other materi-als, or as a dump. As our demandsupon the ocean increase, so doesour need to understand the oceanas an ecosystem. Basic to the un-derstanding of any ecosystem isknowledge of its food web, throughwhich energy and materials flow.(Pomeroy 1974, p. 499)

/pdf/viruses-and-nutrient-cycles-in-the-sea-viruses-play-critical-203g0b6i9i.pdf

Viruses and Nutrient Cycles in the Sea Viruses play critical roles in the structure and function of aquatic food webs

https://www.whoi.edu/cms/files/RueBruland_MarChem1995_52031.pdf

Complexation of iron(III) by natural organic ligands in the Central North Pacific as determined by a new competitive ligand equilibration/adsorptive cathodic stripping voltammetric method

Iron is a limiting nutrient for primary production in large areas of the oceans. Dissolved iron(III) in the upper oceans occurs almost entirely in the form of complexes with strong organic ligands presumed to be of biological origin. Although the importance of organic ligands to aquatic iron cycling is becoming clear, the mechanism by which they are involved in this process remains uncertain. Here we report observations of photochemical reactions involving Fe(III) bound to siderophores--high-affinity iron(III) ligands produced by bacteria to facilitate iron acquisition. We show that photolysis of Fe(III)-siderophore complexes leads to the formation of lower-affinity Fe(III) ligands and the reduction of Fe(III), increasing the availability of siderophore-bound iron for uptake by planktonic assemblages. These photochemical reactions are mediated by the alpha-hydroxy acid moiety, a group which has generally been found to be present in the marine siderophores that have been characterized. We suggest that Fe(III)-binding ligands can enhance the photolytic production of reactive iron species in the euphotic zone and so influence iron availability in aquatic systems.

Photochemical cycling of iron in the surface ocean mediated by microbial iron(III)-binding ligands.

We participated on the Iron-Ex II study in the equatorial Pacific to investigate ambient iron chemistry and its response to a mesoscale iron addition experiment. As expected, dissolved iron values in the high-nutrient, lowchlorophyll surface waters of the South Equatorial Current (4-6”S, 105-109”W) were extremely low (-20 PM). In studies of the chemical speciation of dissolved iron, we found two classes of Fe(III)-binding organic ligands-a strong ligand class (L,) with a conditional stability constant erdl,Fe(I,,), = 5 X lOI* M-l and a mean concentration of 310 pM, and a weaker class (L,) with a conditional stability constant ~~;&e(,,L)8 = 6 X 10” M-l and a mean concentration of 190 pM. The total Fe(III)-binding organic ligand concentrations were -25X higher than total dissolved iron concentrations (-20 PM). Thermodynamic equilibrium calculations indicate that >99.9% of the ambient dissolved Fe(II1) would be complexed with these organic ligands and exist as low-molecular-weight Fe(II1) chelates, with <O.l% (15 fM or -10 I4 M) existing as an inorganic Fe(II1)’ fraction. In the primary Iron-Ex II study, the tbtal Fe(III)-binding ligand concentrations increased by 400% to -2 nM within a day or two after the initial 2 nM mesoscale iron injection. Most of this increase was due to the stronger ligand class, L,, which increased from 0.3 nM to 1.3 nM. The weaker ligand class increased by a similar percentage, although the total magnitude was smaller. Similar increases in Fe(III)-binding ligand concentrations were observed in a secondary Iron-Ex II experiment within 17 h after an initial low-iron 0.4 nM infusion. Results obtained from samples collected throughout the entire course of the iron-enrichment experiments suggest that these Fe(III)-binding organic ligands are produced rapidly in response to small iron additions to this low-iron regime. The chelated iron appears to be directly or in&r&y accessible for growth.

https://aslopubs.onlinelibrary.wiley.com/doi/epdf/10.4319/lo.1997.42.5.0901

The role of organic complexation on ambient iron chemistry in the equatorial Pacific Ocean and the response of a mesoscale iron addition experiment

The supply of iron, relative to that of the macronutrients nitrate, phosphate, and silicic acid, plays a critical role in allowing extensive diatom blooms to develop in coastal upwelling regimes. The presence or absence of a broad continental shelf influences the supply of iron. The iron input to central California upwelling waters varies spatially and can be characterized by two end-member regimes. One end member, which includes Monterey Bay and extending north to Pt. Reyes, is an iron-replete regime where upwelling occurs over a relatively broad continental shelf that results in waters with high concentrations of dissolved and particulate iron ( .10 nM) entrained together with high concentrations of nitrate and silicic acid. In these iron-replete regions, extensive blooms of large diatoms deplete macronutrient concentrations, which results in correspondingly high chlorophyll a concentrations. The other end member, located to the south of Monterey Bay off the Big Sur coast, is an iron-deplete regime where upwelling is focused offshore of a narrow continental shelf. Upwelled waters in the Big Sur region are characterized by low dissolved and particulate iron concentrations (,1 nM), together with high concentrations of nitrate and silicic acid. Extremely low iron concentrations, unused nitrate and silicic acid, and a low abundance of large diatoms characterize surface waters in these iron-deplete regions, and thus represent coastal upwelling, high-nutrient, low-chlorophyll systems limited by the micronutrient iron.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2001.46.7.1661

Iron and macronutrients in California coastal upwelling regimes: Implications for diatom blooms

https://www.es.ucsc.edu/~kbruland/Manuscripts/RUE/Brulandetal2005.pdf

Eden L. Rue

Papers

Complexation of iron(III) by natural organic ligands in the Central North Pacific as determined by a new competitive ligand equilibration/adsorptive cathodic stripping voltammetric method

Photochemical cycling of iron in the surface ocean mediated by microbial iron(III)-binding ligands.

The role of organic complexation on ambient iron chemistry in the equatorial Pacific Ocean and the response of a mesoscale iron addition experiment

Iron and macronutrients in California coastal upwelling regimes: Implications for diatom blooms

Iron, macronutrients and diatom blooms in the Peru upwelling regime: Brown and blue waters of Peru