Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 7 3 2010 10.5194/bg-7-1075-2010 http://www.biogeosciences.net/7/1075/2010/ http://www.biogeosciences.net/7/1075/2010/bg-7-1075-2010.html http://www.biogeosciences.net/7/1075/2010/bg-7-1075-2010.pdf 1075 1097 2010-03-19 Iron biogeochemistry across marine systems – progress from the past decade E. Breitbarth ebreitbarth@chemistry.otago.ac.nz E. P. Achterberg M. V. Ardelan A. R. Baker E. Bucciarelli F. Chever P. L. Croot S. Duggen M. Gledhill M. Hassellöv C. Hassler L. J. Hoffmann K. A. Hunter D. A. Hutchins J. Ingri T. Jickells M. C. Lohan M. C. Nielsdóttir G. Sarthou V. Schoemann J. M. Trapp D. R. Turner Y. Ye Department of Chemistry, University of Otago, Dunedin, New Zealand Department of Chemistry, University of Gothenburg, Gothenburg, Sweden National Oceanography Center Southampton, University of Southampton, Southampton, UK Norwegian University of Science and Technology, Department of Chemistry, Trondheim, Norway School of Environmental Sciences, University of East Anglia, Norwich, UK Université Européenne de Bretagne, France Université de Brest, CNRS, IRD, UMR 6539 LEMAR, IUEM, Plouzané, France IFM-GEOMAR, Leibniz-Institute of Marine Sciences, Division Marine Biogeochemistry, Kiel Germany IFM-GEOMAR, Leibniz-Institute of Marine Sciences, Division Dynamics of the Ocean Floor, Kiel, Germany Centre for Australian Weather and Climate Research (CAWCR), Hobart, TAS, Australia Department of Plant and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA Luleå University of Technology, Division of Applied Geology, LuleÃ¥, Sweden Marine Institute, University of Plymouth, Plymouth, UK Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Bruxelles, Belgium University of Miami, Rosenstiel School of Marine and Atmospheric Science, Department of Marine and Atmospheric Chemistry, Miami, USA Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany Based on an international workshop (Gothenburg, 14–16 May 2008), this review article aims to combine interdisciplinary knowledge from coastal and open ocean research on iron biogeochemistry. The major scientific findings of the past decade are structured into sections on natural and artificial iron fertilization, iron inputs into coastal and estuarine systems, colloidal iron and organic matter, and biological processes. Potential effects of global climate change, particularly ocean acidification, on iron biogeochemistry are discussed. The findings are synthesized into recommendations for future research areas. Aguilar-Islas, A. M., Rember, R. D., Mordy, C. W., and Wu, J.: Sea ice-derived dissolved iron and its potential influence on the spring algal bloom in the Bering Sea, Geophys. Res. Lett., 35, L₂4601, doi:10.1029/2008gl035736, 2008. Ahner, B. A., Morel, F. M. M., and Moffett, J. W.: Trace metal control of phytochelatin production in coastal waters, Limnol. Oceanogr., 42, 601–608, 1997. Aluwihare, L. I., Repeta, D. J., and Chen, R. F.: A major biopolymeric component to dissolved organic carbon in surface sea water, Nature, 387, 166–169, 1997. Andersson, K., Dahlqvist, R., Turner, D., Stolpe, B., Larsson, T., Ingri, J., and Andersson, P.: Colloidal rare earth elements in a boreal river: Changing sources and distributions during the spring flood, Geochim. Cosmochim. Acta, 70, 3261–3274, doi:10.1016/j.gca.2006.04.021, 2006. Ardelan, M. V., Holm-Hansen, O., Hewes, C. D., Reiss, C. S., Silva, N. S., Dulaiova, H., Steinnes, E., and Sakshaug, E.: Natural iron enrichment around the Antarctic Peninsula in the Southern Ocean, Biogeosciences, 7, 11–25, 2010. Assemi, S., Newcombe, G., Hepplewhite, C., and Beckett, R.: Characterization of natural organic matter fractions separated by ultrafiltration using flow field-flow fractionation, Water Res., 38, 1467–1476, doi:10.1016/j.watres.2003.11.031, 2004. Aumont, O. and Bopp, L.: Globalizing results from ocean in situ iron fertilization studies, Global Biogeochem. Cy., 20, GB2017, Gb2017, doi:10.1029/2005gb002591, 2006. Averyt, K. B., Kim, J. P., and Hunter, K. A.: Effect of pH on measurement of strong copper binding ligands in lakes, Limnol. Oceanogr., 49, 20–27, 2004. Baker, A. R. and Jickells, T. D.: Mineral particle size as a control on aerosol iron solubility, Geophys. Res. Lett., 33, L$_1$7608 doi:10.1029/12006GL026557 2006. Baker, A. R., Jickells, T. D., Witt, M., and Linge, K. L.: Trends in the solubility of iron, aluminium, manganese and phosphorus in aerosol collected over the Atlantic Ocean, Mar. Chem., 98, 43–58, doi:10.1016/j.marchem.2005.06.004, 2006. Baker, A. R., and Croot, P. L.: Atmospheric and marine controls on aerosol iron solubility in seawater, Mar. Chem., in press, 2009. Barbeau, K., Moffett, J. W., Caron, D. A., Croot, P. L., and Erdner, D. L.: Role of protozoan grazing in relieving iron limitation of phytoplankton, Nature, 380, 61–64, 1996. Barbeau, K. and Moffett, J. W.: Laboratory and field studies of colloidal iron oxide dissolution as mediated by phagotrophy and photolysis, Limnol. Oceanogr., 45, 827–835, 2000. Barbeau, K., Rue, E. L., Bruland, K. W., and Butler, A.: Photochemical cycling of iron in the surface ocean mediated by microbial iron(III)-binding ligands, Nature, 413, 409–413, 2001. Barbeau, K.: Photochemistry of organic iron(III) complexing ligands in oceanic systems, Photochem. Photobiol., 82, 1505–1516, doi:10.1562/2006-06-16-ir-935, 2006. Bauer, J. E., Williams, P. M., and Druffel, E. R. M.: C-14 activity of dissolved organic-carbon fractions in the North-Central Pacific and Sargasso Sea, Nature, 357, 667–670, 1992. Benitez-Nelson, C. R., Vink, S. M., Carrillo, J. H., and Huebert, B. J.: Volcanically influenced iron and aluminum cloud water deposition to Hawaii, Atmos. Environ., 37, 535–544, 2003. Bergquist, B. A. and Boyle, E. A.: Iron isotopes in the Amazon River system: Weathering and transport signatures, Earth Planet. Sci. Lett., 248, 54–68, doi:10.1016/j.epsl.2006.05.004, 2006. Bergquist, B. A., Wu, J., and Boyle, E. A.: Variability in oceanic dissolved iron is dominated by the colloidal fraction, Geochim. Cosmochim. Acta, 71, 2960–2974, doi:10.1016/j.gca.2007.03.013, 2007. Berman-Frank, I., Rosenberg, G., Levitan, O., Haramaty, L., and Mari, X.: Coupling between autocatalytic cell death and transparent exopolymeric particle production in the marine cyanobacterium Trichodesmium, Environ. Microbiol., 9, 1415–1422, doi:10.1111/j.1462-2920.2007.01257.x, 2007. Blain, S., Queguiner, B., Armand, L., Belviso, S., Bombled, B., Bopp, L., Bowie, A., Brunet, C., Brussaard, C., Carlotti, F., Christaki, U., Corbiere, A., Durand, I., Ebersbach, F., Fuda, J.-L., Garcia, N., Gerringa, L., Griffiths, B., Guigue, C., Guillerm, C., Jacquet, S., Jeandel, C., Laan, P., Lefevre, D., Lo Monaco, C., Malits, A., Mosseri, J., Obernosterer, I., Park, Y.-H., Picheral, M., Pondaven, P., Remenyi, T., Sandroni, V., Sarthou, G., Savoye, N., Scouarnec, L., Souhaut, M., Thuiller, D., Timmermans, K., Trull, T., Uitz, J., van Beek, P., Veldhuis, M., Vincent, D., Viollier, E., Vong, L., and Wagener, T.: Effect of natural iron fertilization on carbon sequestration in the Southern Ocean, Nature, 446, 1070–1074, 2007. Blain, S., Bonnet, S., and Guieu, C.: Dissolved iron distribution in the tropical and sub tropical South Eastern Pacific, Biogeosciences, 5, 269–280, 2008. Boehme, J. and Wells, M.: Fluorescence variability of marine and terrestrial colloids: Examining size fractions of chromophoric dissolved organic matter in the Damariscotta River estuary, Mar. Chem., 101, 95–103, doi:10.1016//j.marchem.2006.02.001, 2006. Bopp, L., Kohfeld, K. E., Le Quere, C., and Aumont, O.: Dust impact on marine biota and atmospheric CO₂ during glacial periods, Paleoceanography, 18, 1046, doi:10.1029/2002pa000810, 2003. Borer, P. M., Sulzberger, B., Reichard, P., and Kraemer, S. M.: Effect of siderophores on the light-induced dissolution of colloidal iron(III) (hydr)oxides, Mar. Chem., 93, 179–193, 2005. Bowie, A. R., Achterberg, E. P., Sedwick, P. N., Ussher, S., and Worsfold, P. J.: Real-time monitoring of picomolar concentrations of iron(II) in marine waters using automated flow injection-chemiluminescence instrumentation, Environ. Sci. Technol., 36, 4600–4607, 2002. Bowie, A. R., Achterberg, E. P., Ussher, S., and Worsfold, P. J.: Design of an automated flow injection-chemiluminescence instrument incorporating a miniature photomultiplier tube for monitoring picomolar concentrations of iron in seawater, Journal of Automated Methods andManagement in Chemistry, 2005, 37–43, doi:10.1155/JAMMC.2005.1137, 2005. Bowie, A. R., Achterberg, E. P., Croot, P. L., de Baar, H. J. W., Laan, P., Moffett, J. W., Ussher, S., and Worsfold, P. J.: A community-wide intercomparison exercise for the determination of dissolved iron in seawater, Mar. Chem., 98, 81–99, 2006. Boyanapalli, R., Bullerjahn, G. S., Pohl, C., Croot, P. L., Boyd, P. W., and McKay, R. M. L.: Luminescent whole-cell cyanobacterial bioreporter for measuring Fe availability in diverse marine environments, Appl. Environ. Microbiol., 73, 1019–1024, doi:10.1128/aem.01670-06, 2007. Boyd, P.: Ironing out algal issues in the southern ocean, Science, 304, 396–397, 2004. Boyd, P. W., Wong, C. S., Merrill, J., Whitney, F., Snow, J., Harrison, P. J., and Gower, J.: Atmospheric iron supply and enhanced vertical carbon flux in the NE subarctic Pacific: Is there a connection?, Global Biogeochem. Cy., 12, 429–441, 1998. Boyd, P. W., Watson, A. J., Law, C. S., and Abraham, E. R.: A mesoscale phytoplankton bloom in the polar Southern Ocean stimulated by iron fertilization, Nature, 407, 695–702, 2000. Boyd, P. W., Crossley, A. C., DiTullio, G. R., Griffiths, F. B., Hutchins, D. A., Queguiner, B., Sedwick, P. N., and Trull, T. W.: Control of phytoplankton growth by iron supply and irradiance in the subantarctic Southern Ocean: Experimental results from the SAZ Project, J. Geophys. Res.-Oceans, 106, 31573–31583, 2001. Boyd, P. W. and Doney, S. C.: Modeling regional responses by marine pelagic ecosystems to global climate change, Geophys. Res. Lett., 29, 5351–5354, 2002. Boyd, P. W. and Doney, S. C.: The impact of climate change and feedback processes on the ocean carbon cycle, in: Ocean Biogeochemistry, Global Change – the IGBP Series, Springer-Verlag Berlin, Berlin, 157–193, 2003. Boyd, P. W., Law, C. S., Wong, C. S., Nojiri, Y., Tsuda, A., Levasseur, M., Takeda, S., Rivkin, R., Harrison, P. J., Strzepek, R., Gower, J., McKay, R. M., Abraham, E., Arychuk, M., Barwell-Clarke, J., Crawford, W., Crawford, D., Hale, M., Harada, K., Johnson, K., Kiyosawa, H., Kudo, I., Marchetti, A., Miller, W., Needoba, J., Nishioka, J., Ogawa, H., Page, J., Robert, M., Saito, H., Sastri, A., Sherry, N., Soutar, T., Sutherland, N., Taira, Y., Whitney, F., Wong, S. K. E., and Yoshimura, T.: The decline and fate of an iron-induced subarctic phytoplankton bloom, Nature, 428, 549–553, 2004. Boyd, P. W., Law, C. S., Hutchins, D. A., Abraham, E. R., Croot, P. L., Ellwood, M., Frew, R. D., Hadfield, M., Hall, J., Handy, S., Hare, C., Higgins, J., Hill, P., Hunter, K. A., LeBlanc, K., Maldonado, M. T., McKay, R. M., Mioni, C., Oliver, M., Pickmere, S., Pinkerton, M., Safi, K., Sander, S., Sanudo-Wilhelmy, S. A., Smith, M., Strzepek, R., Tovar-Sanchez, A., and Wilhelm, S. W.: FeCycle: Attempting an iron biogeochemical budget from a mesoscale SF6 tracer experiment in unperturbed low iron waters, Global Biogeochem. Cy., 19, GB4S20, doi:10.1029/2005GB002494, 2005. Boyd, P. W., Jickells, T., Law, C. S., Blain, S., Boyle, E. A., Buesseler, K. O., Coale, K. H., Cullen, J. J., de Baar, H. J. W., Follows, M., Harvey, M., Lancelot, C., Levasseur, M., Owens, N. P. J., Pollard, R., Rivkin, R. B., Sarmiento, J., Schoemann, V., Smetacek, V., Takeda, S., Tsuda, A., Turner, S., and Watson, A. J.: Mesoscale Iron Enrichment Experiments 1993–2005: Synthesis and Future Directions, Science, 315, 612–617, doi:10.1126/science.1131669, 2007. Boyd, P. W.: Implications of large-scale iron fertilization of the oceans – Introduction and synthesis, Mar. Ecol.-Prog. Ser., 364, 213–218, 2008. Boyd, P. W., Mackie, D. S., and Hunter, K. A.: Aerosol iron deposition to the surface ocean – Modes of iron supply and biological responses, Mar. Chem., in press, doi:10.1016/j.marchem.2009.01.008, 2009. Boye, M., Nishioka, J., Croot, P. L., Laan, P., Timmermans, K. R., and de Baar, H. J. W.: Major deviations of iron complexation during 22 days of a mesoscale iron enrichment in the open Southern Ocean, Mar. Chem., 96, 257–271, 2005. Brand, L. E., Sunda, W. G., and Guillard, R. R. L.: Limitation of marine-phytoplankton reproductive rates by zinc, manganese, and iron Limnol. Oceanogr., 28, 1182–1198, 1983. Breitbarth, E., Gelting, J., Walve, J., Hoffmann, L. J., Turner, D. R., Hassellöv, M., and Ingri, J.: Dissolved iron (II) in the Baltic Sea surface water and implications for cyanobacterial bloom development, Biogeosciences, 6, 2397–2420, 2009. Breitbarth, E., Bellerby, R. J., Neill, C. C., Ardelan, M. V., Meyerhöfer, M., Zöllner, E., Croot, P. L., and Riebesell, U.: Ocean acidification affects iron speciation during a coastal seawater mesocosm experiment, Biogeosciences, 7, 1065–1073, 2010. Bruland, K. W., Rue, E. L., and Smith, G. J.: Iron and macronutrients in California coastal upwelling regimes: Implications for diatom blooms, Limnol. Oceanogr., 46, 1661–1674, 2001. Bucciarelli, E., Pondaven, P., and Sarthou, G.: Effects of an iron-light co-limitation on the elemental composition (Si, C, N) of the marine diatoms \it Thalassiosira oceanica and \it Ditylum brightwellii, Biogeosciences, 7, 657–669, 2010. Buck, K. N., Lohan, M. C., Berger, C. J. M., and Bruland, K. W.: Dissolved iron speciation in two distinct river plumes and an estuary: Implications for riverine iron supply, Limnol. Oceanogr., 52, 843–855, 2007. Buesseler, K. O., Bauer, J. E., Chen, R. F., Eglinton, T. I., Gustafsson, O., Landing, W., Mopper, K., Moran, S. B., Santschi, P. H., VernonClark, R., and Wells, M. L.: An intercomparison of cross-flow filtration techniques used for sampling marine colloids: Overview and organic carbon results, Mar. Chem., 55, 1–31, 1996. Buesseler, K. O., Andrews, J. E., Pike, S. M., and Charette, M. A.: The Effects of Iron Fertilization on Carbon Sequestration in the Southern Ocean, Science, 304, 414–417, 2004. Buesseler, K. O., Doney, S. C., Karl, D. M., Boyd, P. W., Caldeira, K., Chai, F., Coale, K. H., de Baar, H. J. W., Falkowski, P. G., Johnson, K. S., Lampitt, R. S., Michaels, A. F., Naqvi, S. W. A., Smetacek, V., Takeda, S., and Watson, A. J.: Ocean Iron Fertilization – Moving Forward in a Sea of Uncertainty, Science, 319, 162, doi:10.1126/science.1154305, 2008. Caldeira, K. and Wickett, M. E.: Anthropogenic carbon and ocean pH, Nature, 425, 365–365, 2003. Chase, Z., Johnson, K. S., Elrod, V. A., Plant, J. N., Fitzwater, S. E., Pickell, L., and Sakamoto, C. M.: Manganese and iron distributions off central California influenced by upwelling and shelf width, Mar. Chem., 95, 235–254, doi:10.1016/j.marchem.2004.09.006, 2005. Chen, C. Y., and Durbin, E. G.: Effects on pH on the growth and carbon uptake of marine phytoplankton, Marine Ecology Progress Series, 109, 83-94, 1994. Chen, M. and Wang, W. X.: Bioavailability of natural colloid-bound iron to marine plankton: Influences of colloidal size and aging, Limnol. Oceanogr., 46, 1956–1967, 2001. Chever, F., Sarthou, G., Bucciarelli, E., Blain, S., and Bowie, A. R.: An iron budget during the natural iron fertilisation experiment KEOPS (Kerguelen Islands, Southern Ocean), Biogeosciences, 7, 455–468, 2010. Chin, W.-C., Orellana, M. V., and Verdugo, P.: Spontaneous assembly of marine dissolved organic matter into polymer gels, Nature, 391, 568–572, 1998. Chisholm, S. W., Falkowski, P. G., and Cullen, J. J.: Oceans – Dis-crediting ocean fertilization, Science, 294, 309–310, 2001. Coale, K., Johnson, K., Fitzwater, S., Gordon, R., Tanner, S., Chavez, F., Ferioli, L., Sakamoto, C., Rogers, P., Millero, F., Steinberg, P., Nightingale, P., Cooper, D., Cochlan, W., Landry, M., Constantinou, J., Rollwagen, G., Trasvina, A., and Kudela, R.: A massive phytoplankton bloom induced by an ecosystem-scale iron fertilization experiment in the equatorial Pacific Ocean, Nature, 383, 495–501, 1996. Coale, K. H., Johnson, K. S., Chavez, F. P., Buesseler, K. O., Barber, R. T., Brzezinski, M. A., Cochlan, W. P., Millero, F. J., Falkowski, P. G., Bauer, J. E., Wanninkhof, R. H., Kudela, R. M., Altabet, M. A., Hales, B. E., Takahashi, T., Landry, M. R., Bidigare, R. R., Wang, X., Chase, Z., Strutton, P. G., Friederich, G. E., Gorbunov, M. Y., Lance, V. P., Hilting, A. K., Hiscock, M. R., Demarest, M., Hiscock, W. T., Sullivan, K. F., Tanner, S. J., Gordon, R. M., Hunter, C. N., Elrod, V. A., Fitzwater, S. E., Jones, J. L., Tozzi, S., Koblizek, M., Roberts, A. E., Herndon, J., Brewster, J., Ladizinsky, N., Smith, G., Cooper, D., Timothy, D., Brown, S. L., Selph, K. E., Sheridan, C. C., Twining, B. S., and Johnson, Z. I.: Southern Ocean Iron Enrichment Experiment: Carbon Cycling in High- and Low-Si Waters, Science, 304, 408–414, 2004. Croot, P. L., and Johansson, M.: Determination of iron speciation by cathodic stripping voltammetry in seawater using the competing ligand 2-(2-thiazolylazo)-p-cresol (TAC), Electroanalysis, 12, 565–576, 2000. Croot, P. L., Bowie, A. R., Frew, R. D., Maldonado, M. T., Hall, J. A., Safi, K. A., La Roche, J., Boyd, P. W., and Law, C. S.: Retention of dissolved iron and Fe-II in an iron induced Southern Ocean phytoplankton bloom, Geophys. Res. Lett., 28, 3425–3428, 2001. Croot, P. L. and Laan, P.: Continuous shipboard determination of Fe(II) in polar waters using flow injection analysis with chemiluminescence detection, Analytica Chimica Acta, 466, 261–273, 2002. Croot, P. L., Andersson, K., Öztürk, M., and Turner, D. R.: The distribution and speciation of iron along 6° E in the Southern Ocean, Deep Sea Res., 51, 2857–2879, 2004. Croot, P. L., Laan, P., Nishioka, J., Strass, V., Cisewski, B., Boye, M., Timmermans, K. R., Bellerby, R. G., Goldson, L., Nightingale, P., and de Baar, H. J. W.: Spatial and temporal distribution of Fe(II) and H₂O₂ during EisenEx, an open ocean mescoscale iron enrichment, Mar. Chem., 95, 65–88, 2005. Croot, P. L., Bluhm, K., Schlosser, C., Streu, P., Breitbarth, E., Frew, R. D., and Ardelan, M. V.: Cycling of Fe(II) in Southern Ocean Iron Mesoscale Enrichment Experiments: EIFEX and SOFEX, Geophys. Res. Lett., 35, L$_1$9606. doi:19610.11029/12008GL035063, 2008. Cullen, J. J. and Boyd, P. W.: Predicting and verifying the intended and unintended consequences of large-scale ocean iron fertilization, Mar. Ecol. Progress Ser., 364, 295–301, doi:10.3354/meps07551, 2008. Cullen, J. T., Chase, Z., Coale, K. H., Fitzwater, S. E., and Sherrell, R. M.: Effect of iron limitation on the cadmium to phosphorus ratio of natural phytoplankton assemblages from the Southern Ocean, Limnol. Oceanogr., 48, 1079–1087, 2003. Dalbec, A. A. and Twining, B. S.: Remineralization of bioavailable iron by a heterotrophic dinoflagellate, Aquatic Microbial Ecol., 54, 279–290, doi:10.3354/ame01270, 2009. de Baar, H. J. W., Buma, A. G. J., Nolting, R. F., Cadée, G. C., Jacques, G., and Tréguer, P. J.: On iron limitation of the Southern Ocean: experimental observations in the Weddell and Scotia Seas, Mar. Ecol. Progr. Series, 65, 105–122, 1990. de Baar, H. J. W., Dejong, J. T. M., Bakker, D. C. E., Loscher, B. M., Veth, C., Bathmann, U., and Smetacek, V.: Importance of iron for plankton blooms and carbondioxide drawdown in the Southern Ocean, Nature, 373, 412–415, 1995. de Baar, H. J. W., and La Roche, J.: Trace Metals in the Oceans: Evolution, Biology and Global Change, in: Marine Science Frontiers for Europe, edited by: Wefer, G., Lamy, F., and Mantoura, F., Springer Verlag, Berlin, 79–105, 2003. de Baar, H. J. W., Boyd, P. W., Coale, K. H., Landry, M. R., Tsuda, A., Assmy, P., Bakker, D. C. E., Bozec, Y., Barber, R. T., Brzezinski, M. A., Buesseler, K. O., Boye, M., Croot, P. L., Gervais, F., Gorbunov, M. Y., Harrison, P. J., Hiscock, W. T., Laan, P., Lancelot, C., Law, C. S., Levasseur, M., Marchetti, A., Millero, F. J., Nishioka, J., Nojiri, Y., van Oijen, T., Riebesell, U., Rijkenberg, M. J. A., Saito, H., Takeda, S., Timmermans, K. R., Veldhuis, M. J. W., Waite, A. M., and Wong, C. S.: Synthesis of iron fertilization experiments: From the Iron Age in the Age of Enlightenment, J. Geophys. Res., 110, C09S16, doi:10.1029/2004JC002601, 2005. de Baar, H. J. W., Gerringa, L. J. A., Laan, P., and Timmermans, K. R.: Efficiency of carbon removal per added iron in ocean iron fertilization, Mar. Ecol. Progr. Series, 364, 269–282, doi:10.3354/meps07548, 2008. de Jong, J., Schoemann, V., Tison, J. L., Becquevort, S., Masson, F., Lannuzel, D., Petit, J., Chou, L., Weis, D., and Mattielli, N.: Precise measurement of Fe isotopes in marine samples by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), Analytica Chimica Acta, 589, 105–119, doi:10.1016/j.aca.2007.02.055, 2007. Decho, A. W.: Microbial exopolymer secretions in ocean environments – their role(s) in food webs and marine processes, Oceanogr. Mar. Biol., 28, 73–153, 1990. Duce, R. A., Liss, P. S., Merrill, J. T., Atlas, E. L., Buat-Menard, P., Hicks, B. B., Miller, J. M., Prospero, J. M., Arimoto, R., Church, T. M., Ellis, W., Galloway, J. N., Hansen, L., Jickells, T. D., Knap, A. H., Reinhardt, K. H., Schneider, B., Soudine, A., Tokos, J. J., Tsunogai, S., Wollast, R., and Zhou, M.: The atmospheric input of trace species to the world ocean, Global Biogeochem. Cy., 5, 193–259, 1991. Duce, R. A., LaRoche, J., Altieri, K., Arrigo, K. R., Baker, A. R., Capone, D. G., Cornell, S., Dentener, F., Galloway, J., Ganeshram, R. S., Geider, R. J., Jickells, T., Kuypers, M. M., Langlois, R., Liss, P. S., Liu, S. M., Middelburg, J. J., Moore, C. M., Nickovic, S., Oschlies, A., Pedersen, T., Prospero, J., Schlitzer, R., Seitzinger, S., Sorensen, L. L., Uematsu, M., Ulloa, O., Voss, M., Ward, B., and Zamora, L.: Impacts of atmospheric anthropogenic nitrogen on the open ocean, Science, 320, 893–897, doi:10.1126/science.1150369, 2008. Duggen, S., Croot, P., Schacht, U., and Hoffmann, L.: Subduction zone volcanic ash can fertilize the surface ocean and stimulate phytoplankton growth: Evidence from biogeochemical experiments and satellite data, Geophys. Res. Lett., 34, L01612, doi:10.01029/02006GL027522 2007. Duggen, S., Olgun, N., Croot, P., Hoffmann, L., Dietze, H., Delmelle, P., and Teschner, C.: The role of airborne volcanic ash for the surface ocean biogeochemical iron-cycle: a review, Biogeosciences, 7, 827–844, 2010. Dupont, C. L., Yang, S., Palenik, B., and Bourne, P. E.: Modern proteomes contain putative imprints of ancient shifts in trace metal geochemistry, Proc. Natl. Acad. Sci. USA, 103, 17822–17827, doi:10.1073/pnas.0605798103, 2006. Dutkiewicz, S., Follows, M. J., and Parekh, P.: Interactions of the iron and phosphorus cycles: A three-dimensional model study, Global Biogeochem. Cy., 19, GB1021, doi:10.1029/2004gb002342, 2005. Editorial: The Law of the Sea, Nature Geosci., 2, 153–153, doi:10.1038/ngeo464, 2009. Edwards, R. and Sedwick, P.: Iron in East Antarctic snow: Implications for atmospheric iron deposition and algal production in Antarctic waters, Geophys. Res. Lett., 28, 3907–3910, 2001. Elrod, V. A., Berelson, W. M., Coale, K. H., and Johnson, K. S.: The flux of iron from continental shelf sediments: A missing source for global budgets, Geophys. Res. Lett., 31(4), L$_1$2307, doi:10.1029/2004gl020216, 2004. Engel, A., Thoms, S., Riebesell, U., Rochelle-Newall, E., and Zondervan, I.: Polysaccharide aggregation as a potential sink of marine dissolved organic carbon, Nature, 428, 929–932, 2004. Fan, S.-M.: Photochemical and biochemical controls on reactive oxygen and iron speciation in the pelagic surface ocean, Mar. Chem., 109, 152–164, 2008. Fan, S. M., Moxim, W. J., and Levy, H.: Aeolian input of bioavailable iron to the ocean, Geophys. Res. Lett., 33, L07602, doi:10.1029/2005gl024852, 2006. Feely, R. A., Sabine, C. L., Lee, K., Berelson, W., Kleypas, J., Fabry, V. J., and Millero, F. J.: Impact of Anthropogenic CO₂ on the CaCO₃ System in the Oceans, Science, 305, 362–366, doi:10.1126/science.1097329, 2004. Firme, G. F., Rue, E. L., Weeks, D. A., Bruland, K. W., and Hutchins, D. A.: Spatial and temporal variability in phytoplankton iron limitation along the California coast and consequences for Si, N, and C biogeochemistry, Global Biogeochem. Cy., 17(13), 1016, doi:10.1029/2001gb001824, 2003. Floge, S. A. and Wells, M. L.: Variation in colloidal chromophoric dissolved organic matter in the Damariscotta Estuary, Maine, Limnol. Oceanogr., 52, 32–45, 2007. Foster, P. L. and Morel, F. M. M.: Reversal of cadmium toxicity in a diatom: An interaction between cadmium activity and iron, Limnol. Oceanogr., 27, 745–752, 1982. Franck, V. M., Bruland, K. W., Hutchins, D. A., and Brzezinski, M. A.: Iron and zinc effects on silicic acid and nitrate uptake kinetics in three high-nutrient, low-chlorophyll (HNLC) regions, Mar. Ecol.-Prog. Ser., 252, 15–33, 2003. Frew, R. D., Hutchins, D. A., Nodder, S., Sanudo-Wilhelmy, S., Tovar-Sanchez, A., Leblanc, K., Hare, C. E., and Boyd, P. W.: Particulate iron dynamics during FeCycle in subantarctic waters southeast of New Zealand, Global Biogeochemical Cycles, 20, GB1S93, doi:10.1029/2005GB002558, 2006. Frogner, P., Gislason, S. R., and Oskarsson, N.: Fertilizing potential of volcanic ash in ocean surface water, Geology, 29, 487–490, 2001. Fu, F.-X., Mulholland, M. R., Garcia, N. S., Beck, A., Bernhardt, P. W., Warner, M. E., Sañudo-Wilhelmy, S. A., and Hutchins, D. A.: Interactions between changing $p$CO₂, N₂ fixation, and Fe limitation in the marine unicellular cyanobacterium \textitCrocosphaera, Limnol. Oceanogr., 53, 2472–2484, 2008. Furman, J. A. and Capone, D. G.: Possible biogeochemical consequences of ocean fertilization, Limnol. Oceanogr., 36, 1951–1959, 1991. Gelting, J., Breitbarth, E., Stolpe, B., Hassellöv, M., and Ingri, J.: Fractionation of iron species and iron isotopes in the Baltic Sea euphotic zone, Biogeosciences Discuss., 6, 6491–6537, 2009. Gerringa, L. J. A., Rijkenberg, M. J. A., Wolterbeek, H. T., Verburg, T. G., Boye, M., and de Baar, H. J. W.: Kinetic study reveals weak Fe-binding ligand, which affects the solubility of Fe in the Scheldt estuary, Mar. Chem., 103, 30–45, 2007. Gervais, F., Riebesell, U., and Gorbunov, M. Y.: Changes in primary productivity and chlorophyll a in response to iron fertilization in the Southern Polar Frontal Zone, Limnol. Oceanogr., 47, 1324–1335, 2002. Ginoux, P., Prospero, J. M., Torres, O., and Chin, M.: Long-term simulation of global dust distribution with the GOCART model: correlation with North Atlantic Oscillation, Environmental Modelling & Software, 19, 113–128, doi:10.1016/s1364-8152(03)00114-2, 2004. Gledhill, M. and van den Berg, C. M. G.: Determination of compeaxtion of Fe(III) with natural organic complexing ligands in seawater using cathodic stripping voltammetry, Mar. Chem., 47, 41–54, 1994. Gledhill, M.: The determination of heme b in marine phyto- and bacterioplankton, Mar. Chem., 103, 393–403, doi:10.1016/j.marchem.2006.10.008, 2007. Gnanadesikan, A., Sarmiento, J. L., and Slater, R. D.: Effects of patchy ocean fertilization on atmospheric carbon dioxide and biological production, Global Biogeochem.l Cy., 17(17), 1050, doi:10.1029/2002gb001940, 2003. Gonzalez-Davila, M., Santana-Casiano, J. M., and Millero, F. J.: Competition between O-2 and H₂O₂ in the oxidation of Fe(II) in natural waters, J. Solut. Chem., 35, 95–111, 2006. Guieu, C., Bonnet, S., Wagener, T., and Loye-Pilot, M. D.: Biomass burning as a source of dissolved iron to the open ocean?, Geophys. Res. Lett., 32, L$_1$9608, doi:10.11029/12005GL022962, 2005. Gustafsson, O., Widerlund, A., Andersson, P. S., Ingri, J., Roos, P., and Ledin, A.: Colloid dynamics and transport of major elements through a boreal river – brackish bay mixing zone, Mar. Chem., 71, 1–21, 2000. Han, Q., Moore, J. K., Zender, C., Measures, C., and Hydes, D.: Constraining oceanic dust deposition using surface ocean dissolved Al, Global Biogeochem. Cy., 22, GB2003, doi:10.1029/2007gb002975, 2008. Hansard, S. P., Landing, W. M., Measures, C. I., and Voelkar, B. M.: Dissolved iron(II) in the Pacific Ocean: Measurements from PO₂ and P16N Clivar/CO₂ repeat hydrography expeditions, Deep Sea Res. I, 56(7), 1117–1129, 2009. Hare, C. E., DiTullio, G. R., Trick, C. G., Wilhelm, S. W., Bruland, K. W., Rue, E. L., and Hutchins, D. A.: Phytoplankton community structure changes following simulated upwelled iron inputs in the Peru upwelling region, Aquatic Microbial Ecology, 38, 269–282, 2005. Hare, C. E., DiTullio, G. R., Riseman, S. F., Crossley, A. C., Popels, L. C., Sedwick, P. N., and Hutchins, D. A.: Effects of changing continuous iron input rates on a Southern Ocean algal assemblage, Deep-Sea Research Part I-Oceanographic Research Papers, 54, 732–746, doi:10.1016/j.dsr.2007.02.001, 2007a. Hare, C. E., Leblanc, K., DiTullio, G. R., Kudela, R. M., Zhang, Y., Lee, P. A., Riseman, S., and Hutchins, D. A.: Consequences of increased temperature and CO₂ for phytoplankton community structure in the Bering Sea, Marine Ecology Progress Series, 352, 9–16, doi:10.3354/meps07182, 2007b. Hassellöv, M. and von der Kammer, F.: Iron Oxides as Geochemical Nanovectors for Metal Transport in Soil-River Systems, Elements, 4, 401–406, doi:10.2113/gselements.4.6.401, 2008. Hassler, C. S., Slaveykova, V. I., and Wilkinson, K. J.: Discriminating between intra- and extracellular metals using chemical extractions, Limnol. Oceanogr. Methods, 2, 237–247, 2004. Hassler, C. S., Twiss, M. R., McKay, R. M. L., and Bullerjahn, G. S.: Optimization of iron-dependent cyanobacterial (Synechococcus, cyanophyceae) bioreporters to measure iron bioavailability, J. Phycol., 42, 324–335, 2006. Hassler, C. S., Chafin, R. D., Klinger, M. B., and Twiss, M. R.: Application of the biotic ligand model to explain potassium interaction with thallium uptake and toxicity to plankton, Environ. Toxicol. Chem., 26, 1139–1145, 2007. Hassler, C. S. and Schoemann, V.: Bioavailability of organically bound Fe to model phytoplankton of the Southern Ocean, Biogeosciences, 6, 2281–2296, 2009. Heldal, M., Fagerbakke, K. M., Tuomi, P., and Bratbak, G.: Abundant populations of iron and manganese sequestering bacteria in coastal water, Aquatic Microbial Ecology, 11, 127–133, 1996. Ho, T. Y., Quigg, A., Finkel, Z. V., Milligan, A. J., Wyman, K., Falkowski, P. G., and Morel, F. M. M.: The elemental composition of some marine phytoplankton, J. Phycol., 39, 1145–1159, 2003. Hoagland, K. D., Rosowski, J. R., Gretz, M. R., and Roemer, S. C.: Diatom extracellular polymetric substances – function, fine-structure, chemistry, and physiology, J. Phycol., 29, 537–566, 1993. Hoffmann, L. J., Peeken, I., and Lochte, K.: Iron, silicate, and light co-limitation of three Southern Ocean diatom species, Polar Biol., 31, 1067–1080, doi:10.1007/s00300-008-0448-6, 2008. Holm-Hansen, O., Mitchell, B. G., Hewes, C. D., and Karl, D. M.: Phytoplankton blooms in the vicinity of Palmer Station, Antarctica, Polar Biology, 10, 49–57, 1989. Hopkinson, B. M. and Barbeau, K. A.: Organic and redox speciation of iron in the eastern tropical North Pacific suboxic zone, Mar. Chem., 106, 2–17, 2007. Hopkinson, B. M., Roe, K. L., and Barbeau, K. A.: Heme uptake by \textitMicroscilla marina and evidence for heme uptake systems in the genomes of diverse marine bacteria, Appl. Environ. Microbiol., 74, 6263–6270, doi:10.1128/aem.00964-08, 2008. Howell, K. A., Achterberg, E. P., Tappin, A. D., and Worsfold, P. J.: Colloidal metals in the tamar estuary and their influence on metal fractionation by membrane filtration, Environ. Chem., 3, 199–207, doi:10.1071/en06004, 2006. Hudson, R. J. M. and Morel, F. M. M.: Iron transport in marine phytoplankton – kinetics of cellular and medium coordination reactions, Limnol. Oceanogr., 35, 1002–1020, 1990. Hunter, K. A., and Boyd, P. W.: Iron-binding ligands and their role in the ocean biogeochemistry of iron, Environ. Chem., 4, 221–232, doi:10.1071/en07012, 2007. Hurst, M. P. and Bruland, K. W.: An investigation into the exchange of iron and zinc between soluble, colloidal, and particulate size-fractions in shelf waters using low-abundance isotopes as tracers in shipboard incubation experiments, Mar. Chem., 103, 211–226, doi:10.1016/j.marchem.2006.07.001, 2007. Hutchins, D. A. and Bruland, K. W.: Grazer-mediated regeneration and assimilation of Fe, Zn and Mn from planktonic prey, Mar. Ecol. Progr. Series, 110, 259–269, 1994. Hutchins, D. A., Wang, W. X., and Fisher, N. S.: Copepod grazing and the biogeochemical fate of diatom iron, Limnol. Oceanogr., 40, 989–994, 1995. Hutchins, D. A. and Bruland, K. W.: Iron-limited diatom growth and Si:N uptake ratios in a coastal upwelling regime, Nature, 393, 561–564, 1998. Hutchins, D. A., Franck, V. M., Brzezinski, M. A., and Bruland, K. W.: Inducing phytoplankton iron limitation in iron-replete coastal waters with a strong chelating ligand, Limnol. Oceanogr., 44, 1009–1018, 1999a. Hutchins, D. A., Witter, A. E., Butler, A., and Luther III, G. W.: Competition among marine phytoplankton for different chelated iron species, Nature, 400, 858–861, 1999b. Hutchins, D. A., Pustizzi, F., Hare, C. E., and DiTullio, G. R.: A shipboard natural community continuous culture system for ecologically relevant low-level nutrient enrichment experiments, Limnol. Oceanogr.-Methods, 1, 82–91, 2003. Ingri, J., Malinovsky, D., Rodushkin, I., Baxter, D. C., Widerlund, A., Andersson, P., Gustafsson, O., Forsling, W., and Ohlander, B.: Iron isotope fractionation in river colloidal matter, Earth Planet. Sci. Lett., 245, 792–798, 2006. Jacobson, M. Z.: Studying ocean acidification with conservative, stable numerical schemes for nonequilibrium air-ocean exchange and ocean equilibrium chemistry, J. Geophys. Res.-Atmos., 110, D07302, doi:10.01029/02004JD005220 2005. Jickells, T. and Spokes, L. J.: Atmospheric iron inputs into the oceans, in: The Biogeochemistry of Iron in Seawater, edited by: Turner, D. R., and Hunter, K. A., John Wiley and Sons Ltd., West Sussex, England, 85–121, 2001. Jickells, T. D., Dorling, S., Deuser, W. G., Church, T. M., Arimoto, R., and Prospero, J. M.: Air-borne dust fluxes to a deep water sediment trap in the Sargasso Sea, Global Biogeochem. Cy., 12, 311–320, 1998. Jickells, T. D., An, Z. S., Andersen, K. K., Baker, A. R., Bergametti, G., Brooks, N., Cao, J. J., Boyd, P. W., Duce, R. A., Hunter, K. A., Kawahata, H., Kubilay, N., laRoche, J., Liss, P. S., Mahowald, N., Prospero, J. M., Ridgwell, A. J., Tegen, I., and Torres, R.: Global Iron Connections Between Desert Dust, Ocean Biogeochemistry, and Climate, Science, 308, 67–71, 2005. Johnson, K. S.: Iron supply and demand in the upper ocean: Is extraterrestrial dust a significant source of bioavailable iron?, Glob. Biogeochem. Cy., 15, 61–63, 2001. Johnson, K. S., Boyle, E., Bruland, K. W., Coale, K., Measures, C., Moffett, J., Aguilar-Islas, A., Barbeau, K., Bergquist, B., Bowie, A., Buck, K., Cai, Y., Chase, Z., Cullen, J., Doi, T., Elrod, V., Fitzwater, S., Gordon, M., King, A., Laan, P., Laglera-Baquer, L., Landing, W., Lohan, M., Mendez, J., Milne, A., Obata, H., Ossiander, L., Plant, J., Sarthou, G., Sedwick, P., Smith, G. J., Sohst, B., Tanner, S., van den Berg, S., and Wu, J.: The SAFe Iron Intercomparison Cruise: An International Collaboration to Develop Dissolved Iron in Seawater Standards, EOS, Transactions of the American Geophysical Union, 88, 131–132, 2007. Johnson, W. K., Miller, L. A., Sutherland, N. E., and Wong, C. S.: Iron transport by mesoscale Haida eddies in the Gulf of Alaska, Deep-Sea Res., 52, 933–953, doi:10.1016/j.dsr2.2004.08.017, 2005. Jones, M. T. and Gislason, S. R.: Rapid releases of metal salts and nutrients following the deposition of volcanic ash into aqueous environments, Geochim. Cosmochim. Acta, 72, 3661–3680, 2008. Journet, E., Desboeufs, K. V., Caquineau, S., and Colin, J. L.: Mineralogy as a critical factor of dust iron solubility, Geophys. Res. Lett., 35, L07805, doi:10.1029/2007gl031589, 2008. Kintisch, E.: Carbon sequestration: Should oceanographers pump iron?, Science, 318, 1368–1370, 2007. Kondo, Y., Takeda, S., Nishioka, J., Obata, H., Furuya, K., Johnson, W. K., and Wong, C. S.: Organic iron(III) complexing ligands during an iron enrichment experiment in the western subarctic North Pacific, Geophys. Res. Lett., 35, L$_1$2601, doi:10.1029/2008gl033354, 2008. Krachler, R., Jirsa, F., and Ayromlou, S.: Factors influencing the dissolved iron input by river water to the open ocean, Biogeosciences, 2, 311–315, 2005. Lacan, F., Radic, A., Jeandel, C., Poitrasson, F., Sarthou, G., Pradoux, C., and Freydier, R.: Measurement of the isotopic composition of dissolved iron in the open ocean, Geophys. Res. Lett., 35, L₂4610, doi:10.1029/2008gl035841, 2008. La\"es, A., Blain, S., Laan, P., Achterberg, E. P., Sarthou, G., and de Baar, H. J. W.: Deep dissolved iron profiles in the eastern North Atlantic in relation to water masses, Geophys. Res. Lett., 30(4), 1902, doi:10.1029/2003gl017902, 2003. La\"es, A., Blain, S., Laan, P., Ussher, S. J., Achterberg, E. P., Tréguer, P., and de Baar, H. J. W.: Sources and transport of dissolved iron and manganese along the continental margin of the Bay of Biscay, Biogeosciences, 4, 181–194, 2007. Laglera, L. M. and van den Berg, C. M. G.: Evidence for geochemical control of iron by humic substances in seawater, Limnol. Oceanogr., 54, 610–619, 2009. Lam, C. K. S. C. C., Jickells, T. D., Richardson, D. J., and Russell, D. A.: Fluorescence-Based Siderophore Biosensor for the Determination of Bioavailable Iron in Oceanic Waters, Anal. Chem., 78, 5040–5045, doi:10.1021/ac060223t, 2006. Lam, P. J. and Bishop, J. K. B.: The continental margin is a key source of iron to the HNLC North Pacific Ocean, Geophys. Res. Lett., 35(5), L07608, doi:10.1029/2008gl033294, 2008. Lancelot, C., de Montety, A., Goosse, H., Becquevort, S., Schoemann, V., Pasquer, B., and Vancoppenolle, M.: Spatial distribution of the iron supply to phytoplankton in the Southern Ocean: a model study, Biogeosciences, 6, 2861–2878, 2009. Lannuzel, D., Schoemann, V., de Jong, J., Tison, J. L., and Chou, L.: Distribution and biogeochemical behaviour of iron in the East Antarctic sea ice, Mar. Chem., 106, 18–32, doi:10.1016/j.marchem.2006.06.010, 2007. Lannuzel, D., Schoemann, V., de Jong, J., Chou, L., Delille, B., Becquevort, S., and Tison, J.-L.: Iron study during a time series in the western Weddell pack ice, Mar. Chem., 108, 85–95, 2008. Liss, P., Chuck, A., Bakker, D., and Turner, S.: Ocean fertilization with iron: effects on climate and air quality, Tellus Ser. B-Chem. Phys. Meteorol., 57, 269–271, 2005. Liu, X. W. and Millero, F. J.: The solubility of iron hydroxide in sodium chloride solutions, Geochim. Cosmochim. Acta, 63, 3487–3497, 1999. Liu, X. W. and Millero, F. J.: The solubility of iron in seawater, Mar. Chem., 77, 43–54, 2002. Lohan, M. C. and Bruland, K. W.: Importance of vertical mixing for additional sources of nitrate and iron to surface waters of the Columbia River plume: Implications for biology, Mar. Chem., 98, 260–273, doi:10.1016/j.marchem.2005.10.003, 2006. Loscher, B. M., DeBaar, H. J. W., DeJong, J. T. M., Veth, C., and Dehairs, F.: The distribution of Fe in the Antarctic Circumpolar Current, Deep-Sea Res., 44, 143–187, 1997. Luo, C., Mahowald, N., Bond, T., Chuang, P. Y., Artaxo, P., Siefert, R., Chen, Y., and Schauer, J.: Combustion iron distribution and deposition, Global Biogeochem. Cy., 22(17), GB1012, doi:10.1029/2007gb002964, 2008. Lyvén, B., Hassellov, M., Turner, D. R., Haraldsson, C., and Andersson, K.: Competition between iron- and carbon-based colloidal carriers for trace metals in a freshwater assessed using flow field-flow fractionation coupled to ICPMS, Geochim. Cosmochim. Acta, 67, 3791–3802, 2003. Mackey, D. J., O'Sullivan, J. E., and Watson, R. J.: Iron in the western Pacific: a riverine or hydrothermal source for iron in the Equatorial Undercurrent?, Deep-Sea Res., 49, 877–893, 2002. Mahowald, N., Jickells, T. D., Baker, A. R., Artaxo, P., Benitez-Nelson, C. R., Bergametti, G., Bond, T. C., Chen, Y., Cohen, D. D., Herut, B., Kubilay, N., Losno, R., Luo, C., Maenhaut, W., McGee, K. A., Okin, G. S., Siefert, R. L., and Tsukuda, S.: Global distribution of atmospheric phosphorus sources, concentrations and deposition rates, and anthropogenic impacts, Global Biogeochem. Cy., 22, GB4026, doi:10.1029/2008gb003240, 2008. Mahowald, N. M., Baker, A. R., Bergametti, G., Brooks, N., Duce, R. A., Jickells, T. D., Kubilay, N., Prospero, J. M., and Tegen, I.: Atmospheric global dust cycle and iron inputs to the ocean, Global Biogeochem. Cy., 19, GB4025, doi:10.1029/2004gb002402, 2005. Maldonado, M. T., Boyd, P. W., Harrison, P. J., and Price, N. M.: Co-limitation of phytoplankton growth by light and Fe during winter in the NE subarctic Pacific Ocean, Deep-Sea Res., 46, 2475–2485, 1999. Maldonado, M. T., Strzepek, R. F., Sander, S., and Boyd, P. W.: Acquisition of iron bound to strong organic complexes, with different Fe binding groups and photochemical reactivities, by plankton communities in Fe-limited subantarctic waters, Global Biogeochem., 19, GB4S23, doi:10.1029/2005GB002481, 2005. Marchetti, A., Parker, M. S., Moccia, L. P., Lin, E. O., Arrieta, A. L., Ribalet, F., Murphy, M. E. P., Maldonado, M. T., and Armbrust, E. V.: Ferritin is used for iron storage in bloom-forming marine pennate diatoms, Nature, 457, 467–470, doi:10.1038/nature07539, 2009. Martin, J. H.: Glacial-interglacial CO₂ change: the iron hypothesis, Paleoceanography, 5, 1–13, 1990. Mawji, E., Gledhill, M., Milton, J. A., Tarran, G. A., Ussher, S., Thompson, A., Wolff, G. A., Worsfold, P. J., and Achterberg, E. P.: Hydroxamate Siderophores: Occurrence and Importance in the Atlantic Ocean, Environ. Sci. Technol., 42, 8675–8680, doi:10.1021/es801884r, 2008. McKay, R., Michael, L, la Roche, J., Yakunin, A., F, Durnford, D. G., and Geider, R. J.: Accumulation of Ferredoxin and Flavodoxin in a Marine Diatom in response to Fe, J. Phycology, 35, 510–519, 1999. Millero, F. J., Sotolongo, S., and Izaguirre, M.: The oxidation kinetics of Fe(II) in seawater, Geochim. Cosmochim. Acta, 51, 793–801, 1987. Millero, F. J. and Sotolongo, S.: The oxidation of Fe(II) with H₂O₂ in seawater, Geochim. Cosmochim. Acta, 53, 1867–1873, 1989. Mills, M. M., Ridame, C., Davey, M., La Roche, J., and Geider, R. J.: Iron and phosphorus co-limits nitrogen fixation in the eastern tropical North Atlantic, Nature, 429, 292–294, 2004. Moore, C. M., Mills, M. M., Milne, A., Langlois, R., Achterberg, E. P., Lochte, K., Geider, R. J., and La Roche, J.: Iron limits primary productivity during spring bloom development in the central North Atlantic, Global Change Biol., 12, 626–634 doi:610.1111/j.1365-2486.2006.01122.x, 2006. Moore, C. M., Hickman, A. E., Poulton, A. J., Seeyave, S., and Lucas, M. I.: Iron-light interactions during the CROZet natural iron bloom and EXport experiment (CROZEX): II – Taxonomic responses and elemental stoichiometry, Deep-Sea Res., 54, 2066–2084, doi:10.1016/j.dsr2.2007.06.015, 2007a. Moore, C. M., Seeyave, S., Hickman, A. E., Allen, J. T., Lucas, M. I., Planquette, H., Pollard, R. T., and Poulton, A. J.: Iron-light interactions during the CROZet natural iron bloom and EXport experiment (CROZEX) I: Phytoplankton growth and photophysiology, Deep-Sea Res., 54, 2045–2065, doi:10.1016/j.dsr2.2007.06.011, 2007b. Moran, S. B., Yeats, P. A., and Balls, P. W.: On the role of colloids in trace metal solid-solution partitioning in continental shelf waters: A comparison of model results and field data, Cont. Shelf Res., 16, 397–408, 1996. Morel, F. M. M. and Price, N. M.: The biogeochemical cycles of trace metals in the oceans, Science, 300, 944–947, 2003. Morel, F. M. M., Kustka, A. B., and Shaked, Y.: The role of unchelated Fe in the iron nutrition of phytoplankton, Limnol. Oceanogr., 53, 400–404, 2008. Mosley, L. M., Hunter, K. A., and Ducker, W. A.: Forces between colloid particles in natural waters, Environ. Sci. Technol., 37, 3303–3308, doi:10.1021/es026216d, 2003. Mylon, S. E., Chen, K. L., and Elimelech, M.: Influence of natural organic matter and ionic composition on the kinetics and structure of hematite colloid aggregation: Implications to iron depletion in estuaries, Langmuir, 20, 9000–9006, doi:10.1021/la049153g, 2004. Nowostawska, U., Kim, J. P., and Hunter, K. A.: Aggregation of riverine colloidal iron in estuaries: A new kinetic study using stopped-flow mixing, Mar. Chem., 110, 205–210, 2008. Nunn, B. L. and Timperman, A. T.: Marine Proteomics, Mar. Ecol. Progr. Series, 332, 281–289, 2007. Orr, J. C., Fabry, V. J., Aumont, O., Bopp, L., Doney, S. C., Feely, R. A., Gnanadesikan, A., Gruber, N., Ishida, A., Joos, F., Key, R. M., Lindsay, K., Maier-Reimer, E., Matear, R., Monfray, P., Mouchet, A., Najjar, R. G., Plattner, G. K., Rodgers, K. B., Sabine, C. L., Sarmiento, J. L., Schlitzer, R., Slater, R. D., Totterdell, I. J., Weirig, M. F., Yamanaka, Y., and Yool, A.: Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms, Nature, 437, 681–686, 2005. Öztürk, M., Steinnes, E., and Sakshaug, E.: Iron Speciation in the Trondheim Fjord from the Perspective of Iron Limitation for Phytoplankton, Estuarine, Coastal Shelf Sci.e, 55, 197–212, 2002. Öztürk, M. and Bizsel, N.: Iron speciation and biogeochemistry in different nearshore waters, Mar. Chem., 83, 145–156, 2003. Öztürk, M., Croot, P. L., Bertilsson, S., Abrahamsson, K., Karlson, B., David, R., Fransson, A., and Sakshaug, E.: Iron enrichment and photoreduction of iron under UV and PAR in the presence of hydroxycarboxylic acid: implications for phytoplankton growth in the Southern Ocean, Deep Sea Res., 51, 2841–2856, 2004. Paytan, A., Mackey, K. R. M., Chen, Y., Lima, I. D., Doney, S. C., Mahowald, N., Labiosa, R., and Postf, A. F.: Toxicity of atmospheric aerosols on marine phytoplankton, Proc. Natl. Acad. Sci. USA, 106, 4601–4605, di:10.1073/pnas.0811486106, 2009. Peers, G. and Price, N. M.: Copper-containing plastocyanin used for electron transport by an oceanic diatom, Nature, 441, 341–344, 2006. Pickell, L. D., Wells, M. L., Trick, C. G., and Cochlan, W. P.: A sea-going continuous culture system for investigating phytoplankton community response to macro- and micro-nutrient manipulations, Limnol. Oceanogr.-Methods, 7, 21–32, 2009. Planquette, H., Statham, P. J., Fones, G. R., Charette, M. A., Moore, C. M., Salter, I., Nedelec, F. H., Taylor, S. L., French, M., Baker, A. R., Mahowald, N., and Jickells, T. D.: Dissolved iron in the vicinity of the Crozet Islands, Southern Ocean, Deep-Sea Res., 54, 1999–2019, doi:10.1016/j.dsr2.2007.06.019, 2007. Pollard, R. T., Salter, I., Sanders, R. J., Lucas, M. I., Moore, C. M., Mills, R. A., Statham, P. J., Allen, J. T., Baker, A. R., Bakker, D. C. E., Charette, M. A., Fielding, S., Fones, G. R., French, M., Hickman, A. E., Holland, R. J., Hughes, J. A., Jickells, T. D., Lampitt, R. S., Morris, P. J., Nedelec, F. H., Nielsdottir, M., Planquette, H., Popova, E. E., Poulton, A. J., Read, J. F., Seeyave, S., Smith, T., Stinchcombe, M., Taylor, S., Thomalla, S., Venables, H. J., Williamson, R., and Zubkov, M. V.: Southern Ocean deep-water carbon export enhanced by natural iron fertilization, Nature, 457, 577–580, 2009. Powell, R. T. and Wilson-Finelli, A.: Importance of organic Fe complexing ligands in the Mississippi River plume, Estuarine, Coastal Shelf Sci., 58, 757–763, 2003. Prospero, J. M., Ginoux, P., Torres, O., Nicholson, S. E., and Gill, T. E.: Environmental characterization of global sources of atmospheric soil dust identified with the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) absorbing aerosol product, Rev. Geophys., 40, 1002, doi:1010.1029/2000RG000095, 2002. Pulido-Villena, E., Wagener, T., and Guieu, C.: Bacterial response to dust pulses in the western Mediterranean: Implications for carbon cycling in the oligotrophic ocean, Global Biogeochem. Cy., 22(12), GB1020, doi:10.1029/2007GB003091, 2008. Quigg, A., Finkel, Z. V., Irwin, A. J., Rosenthal, Y., Ho, T. Y., Reinfelder, J. R., Schofield, O., Morel, F. M. M., and Falkowski, P. G.: The evolutionary inheritance of elemental stoichiometry in marine phytoplankton, Nature, 425, 291–294, 2003. Raiswell, R., Tranter, M., Benning, L. G., Siegert, M., De'ath, R., Huybrechts, P., and Payne, T.: Contributions from glacially derived sediment to the global iron (oxyhydr)oxide cycle: Implications for iron delivery to the oceans, Geochim. Cosmochim. Acta, 70, 2765–2780, doi:10.1016/j.gca.2005.12.027, 2006. Raiswell, R., Benning, L. G., Tranter, M., and Tulaczyk, S.: Bioavailable iron in the Southern Ocean: the significance of the iceberg conveyor belt, Geochem. Trans., 9(7), doi:10.1186/1467-4866-9-7, 2008. Riebesell, U., Schulz, K. G., Bellerby, R. G. J., Botros, M., Fritsche, P., Meyerhofer, M., Neill, C., Nondal, G., Oschlies, A., Wohlers, J., and Zollner, E.: Enhanced biological carbon consumption in a high CO₂ ocean, Nature, 450, 545–510, doi:10.1038/nature06267, 2007. Rose, A. L.: Effect of Dissolved Natural Organic Matter on the Kinetics of Ferrous Iron Oxygenation in Seawater, Environ. Sci. Technol., 37, 4877–4886, doi:10.1021/es034152g, 2003. Rose, J. M., Feng, Y., DiTullio, G. R., Dunbar, R. B., Hare, C. E., Lee, P. A., Lohan, M., Long, M., W. O. Smith Jr., Sohst, B., Tozzi, S., Zhang, Y., and Hutchins, D. A.: Synergistic effects of iron and temperature on Antarctic phytoplankton and microzooplankton assemblages, Biogeosciences, 6, 3131–3147, 2009. Roy, E. G., Jiang, C. H., Wells, M. L., and Tripp, C.: Determining subnanomolar iron concentrations in oceanic seawater using a siderophore-modified film analyzed by infrared spectroscopy, Anal. Chem., 80, 4689–4695, doi:10.1021/ac800356p, 2008a. Roy, E. G., Wells, M. L., and King, D. W.: Persistence of iron(II) in surface waters of the western subarctic Pacific, Limnol. Oceanogr., 53, 89–98, 2008b. Rue, E. L. and Bruland, K. W.: 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, Mar. Chem., 50, 117–138, 1995. Rue, E. L. and Bruland, K. W.: The role of organic complexation on ambient iron chemistry in the equatorial Pacific Ocean and the response of a mesoscale iron addition experiment, Limnol. Oceanogr., 42, 901–910, 1997. Rusch, D. B., Halpern, A. L., Sutton, G., Heidelberg, K. B., Williamson, S., Yooseph, S., Wu, D., Eisen, J. A., Hoffman, J. M., Remington, K., Beeson, K., Tran, B., Smith, H., Baden-Tillson, H., Stewart, C., Thorpe, J., Freeman, J., Andrews-Pfannkoch, C., Venter, J. E., Li, K., Kravitz, S., Heidelberg, J. F., Utterback, T., Rogers, Y. H., Falcón, L. I., Souza, V., Bonilla-Rosso, G., Eguiarte, L. E., Karl, D. M., Sathyendranath, S., Platt, T., Bermingham, E., Gallardo, V., Tamayo-Castillo, G., Ferrari, M. R., Strausberg, R. L., Nealson, K., Friedman, R., Frazier, M., and Venter, J. C.: The Sorcerer II Global Ocean Sampling expedition: northwest Atlantic through eastern tropical Pacific, PLoS biology, 5(e77), 398–431, 2007. Saito, M. A., Sigman, D. M., and Morel, F. M. M.: The bioinorganic chemistry of the ancient ocean: the co- evolution of cyanobacterial metal requirements and biogeochemical cycles at the Archean-Proterozoic boundary?, Inorganic Chimica Acta, 356, 308–318, 2003. Salmon, T. P., Rose, A. L., Neilan, B. A., and Waite, T. D.: The FeL model of iron acquisition: Nondissociative reduction of ferric complexes in the marine environment, Limnol. Oceanogr., 51, 1744–1754, 2006. Sander, S., Mosley, L. M., and Hunter, K. A.: Investigation of interparticle forces in natural waters: Effects of adsorbed humic acids on iron oxide and alumina surface properties, Environ. Sci. Technol., 38, 4791–4796, doi:10.1021/es049602z, 2004. Sander, S., Ginon, L., Anderson, B., and Hunter, K. A.: Comparative study of organic Cd and Zn complexation in lake waters – seasonality, depth and pH dependence, Environ. Chem., 4, 410–423, 2007. Santana-Casiano, J. M., Gonzalez-Davila, M., and Millero, F. J.: Oxidation of Nanomolar Levels of Fe(II) with Oxygen in Natural Waters, Environ. Sci. Technol., 39, 2073–2079, 2005. Santana-Casiano, J. M., Gonzalez-Davila, M., and Millero, F. J.: The role of Fe(II) species on the oxidation of Fe(II) in natural waters in the presence of O₂ and H₂O₂, Mar. Chem., 99, 70–82, 2006. Santschi, P. H., Balnois, E., Wilkinson, K. J., Zhang, J. W., Buffle, J., and Guo, L. D.: Fibrillar polysaccharides in marine macromolecular organic matter as imaged by atomic force microscopy and transmission electron microscopy, Limnol. Oceanogr., 43, 896–908, 1998. Sarmiento, J. L. and Orr, J. C.: 3-dimensional simulations of the impact of Southern-Ocean nutrient depletion on atmospheric CO₂ and ocean chemistry, Symp on What Controls Phytoplankton Production in Nutrient-Rich Areas of the Open Sea, San Marcos, Ca, 1991, ISI:A1991HR98100032, 1928–1950, Sarthou, G., Timmermans, K. R., Blain, S., and Treguer, P.: Growth physiology and fate of diatoms in the ocean: a review, J. Sea Res., 53, 25–42, 2005. Sarthou, G., Vincent, D., Christaki, U., Obernosterer, I., Timmermans, K. R., and Brussaard, C. P. D.: The fate of biogenic iron during a phytoplankton bloom induced by natural fertilisation: Impact of copepod grazing, Deep-Sea Res., 55, 734–751, doi:10.1016/j.dsr2.2007.12.033, 2008. Sato, M., Takeda, S., and Furuya, K.: Iron regeneration and organic iron(III)-binding ligand production during in situ zooplankton grazing experiment, Mar. Chem., 106, 471–488, 2007. Schmincke, H.-U.: Volcanism, Springer-Verlag, Berlin Heidelberg New York, 324 pp., 2004. Schoemann, V., Wollast, R., Chou, L., and Lancelot, C.: Effects of photosynthesis on the accumulation of Mn and Fe by Phaeocystis colonies, Limnol. Oceanogr., 46, 1065–1076, 2001. Schoemann, V., De Jong, J. T. M., Lannuzel, D., Tison, J. L., Dellile, B., Chou, L., Lancelot, C., and Becquevort, S.: Microbiological control on the cycling Fe and its isotopes in Antarctic sea ice, 8th Annual V M Goldschmidt Conference, Vancouver, CANADA, ISI:000257301602198, A837–A837, 2008. Schroth, A. W., Crusius, J., Sholkovitz, E. R., and Bostick, B. C.: Iron solubility driven by speciation in dust sources to the ocean, Nature Geosci., 2, 337–340, 2009. Schulz, K. G., Zondervan, I., Gerringa, L. J. A., Timmermans, K. R., Veldhuis, M. J. W., and Riebesell, U.: Effect of trace metal availability on coccolithophorid calcification, Nature, 430, 673–676, 2004. Sedwick, P. N., Sholkovitz, E. R., and Church, T. M.: Impact of anthropogenic combustion emissions on the fractional solubility of aerosol iron: Evidence from the Sargasso Sea, Geochem. Geophys. Geosyst., 8, 21, Q10q06, doi:10.1029/2007gc001586, 2007. Shaked, Y., Kustka, A. B., Morel, F. M. M., and Erel, Y.: Simultaneous determination of iron reduction and uptake by phytoplankton, Limnol. Oceanogr.-Methods, 2, 137–145, 2004. Shaked, Y., Kustka, A. B., and Morel, F. M. M.: A general kinetic model for iron acquisition by eukaryotic phytoplankton, Limnol. Oceanogr., 50, 872–882, 2005. Sholkovitz, E. R.: Flocculation of dissolved Fe, Mn, Al, Cu, Ni,Co, and Cd during estuarine mixing, Earth Planet. Sci. Lett., 41, 77–86, 1978. Sholkovitz, E. R., Boyle, E. A., and Price, N. B.: Removal of dissolved humic acids and iron during estuarine mixing, Earth Planet. Sci. Lett., 40, 130–136, 1978. Sigman, D. M. and Boyle, E. A.: Glacial/interglacial variations in atmospheric carbon dioxide, Nature, 407, 859–869, 2000. Sillen, L. G. and Martell, A. E.: Stability Constants, Chemical Society, London, 1971. Smith, K. L., Robison, B. H., Helly, J. J., Kaufmann, R. S., Ruhl, H. A., Shaw, T. J., Twining, B. S., and Vernet, M.: Free-drifting icebergs: Hot spots of chemical and biological enrichment in the Weddell Sea, Science, 317, 478–482, doi:10.1126/science.1142834, 2007. Smith, W. O. and Nelson, D. M.: Phytoplankton bloom produced by a receeding ice edge in the Ross Sea – spacial coherence with the density field, Science, 227, 163–166, 1985. Spokes, L. and Jickells, T. D.: Speciation of metals in the atmosphere, in: Chemical Speciation in the Environment, edited by: Ure, A. and Davidson, C., Blackwell, Malden, 159–187, 2002. Statham, P. J., Skidmore, M., and Tranter, M.: Inputs of glacially derived dissolved and colloidal iron to the coastal ocean and implications for primary productivity, Global Biogeochem. Cy., 22, GB3013, doi:10.1029/2007gb003106, 2008. Steigenberger, S., Statham, P. J., Völker, C., and Passow, U.: The role of polysaccharides and diatom exudates in the redox cycling of Fe and the photoproduction of hydrogen peroxide in coastal seawaters, Biogeosciences, 7, 109–119, 2010. Stolpe, B., Hassellöv, M., Andersson, K., and Turner, D. R.: High resolution ICPMS as an on-line detector for flow field-flow fractionation; multi-element determination of colloidal size distributions in a natural water sample, Analytica Chimica Acta, 535, 109–121, 2005. Stolpe, B. and Hassellöv, M.: Changes in size distribution of fresh water nanoscale colloidal matter and associated elements on mixing with seawater, Geochim. Cosmochim. Acta, 71, 3292–3301, 2007. Stolpe, B., and Hassellöv, M.: Colloidal biopolymers binding iron, copper, silver, lanthanum and lead in coastal seawater – significance for the seasonal and spatial variations in element size distributions, Limnol. Oceanogr., 55(1), 187–202, 2010. Straub, S. M. and Schmincke, H. U.: Evaluating the tephra input into Pacific Ocean sediments: distribution in space and time, Geologische Rundschau, 87, 461–476, 1998. Strzepek, R. F. and Harrison, P. J.: Photosynthetic architecture differs in coastal and oceanic diatoms, Nature, 431, 689–692, 2004. Strzepek, R. F., Maldonado, M. T., Higgins, J. L., Hall, J., Safi, K., Wilhelm, S. W., and Boyd, P. W.: Spinning the "Ferrous Wheel": The importance of the microbial community in an iron budget during the FeCycle experiment, Global Biogeochem. Cy., 19, GB4S26, doi:10.1029/2005GB002490, 2005. Sunda, W. and Huntsman, S.: Effect of pH, light, and temperature on Fe-EDTA chelation and Fe hydrolysis in seawater, Mar. Chem., 84, 35–47, 2003. Sunda, W. G. and Huntsman, S. A.: Effect of competitive interactions between manganese and copper on cellular manganese and growth in estuarine and oceanic species of the diatom Thalassiosira, Limnol. Oceanogr., 28, 924–934, 1983. Sunda, W. G. and Huntsman, S. A.: Iron uptake and growth limitation in oceanic and coastal phytoplankton, Mar. Chem., 50, 189–206, 1995. Sunda, W. G. and Huntsman, S. A.: Processes regulating cellular metal accumulation and physiological effects: Phytoplankton as a model system, The Sciences of the Total Environment, 219, 165–181, 1998. Sunda, W. G. and Huntsman, S. A.: Effect of Zn, Mn, and Fe on Cd accumulation in phytoplankton: Implications for oceanic Cd cycling, Limnol. Oceanogr., 45, 1501–1516, 2000. Takeda, S.: Influence of iron availability on nutrient consumption ratio of diatoms in oceanic waters, Nature, 393, 774–777, 1998. Timmermans, K. R., van der Wagt, B., Veldhuis, M. J. W., Maatman, A., and de Baar, H. J. W.: Physiological responses of three species of marine pico-phytoplankton to ammonium, phosphate, iron and light limitation, J. Sea Res., 53, 109–120, 2005. Toner, B. M., Fakra, S. C., Manganini, S. J., Santelli, C. M., Marcus, M. A., Moffett, J., Rouxel, O., German, C. R., and Edwards, K. J.: Preservation of iron(II) by carbon-rich matrices in a hydrothermal plume, Nature Geosci., 2, 197–201, doi:10.1038/ngeo433, 2009. Tovar-Sanchez, A., Sanudo-Wilhelmy, S. A., Kustka, A. B., Agusti, S., Dachs, J., Hutchins, D. A., Capone, D. G., and Duarte, C. M.: Effects of dust deposition and river discharges on trace metal composition of Trichodesmium spp. in the tropical and subtropical North Atlantic Ocean, Limnol. Oceanogr., 51, 1755–1761, 2006. Tovar-Sanchez, A., Duarte, C. M., Hernández-León, S., and Sañudo-Wilhelmy, S. A.: Krill as a central node for iron cycling in the Southern Ocean, Geophys. Res. Lett., 34, L$_1$1601, doi:10.1029/12006GL029096, 022007, 2007. Trapp, J. M., Millero, F. J., and Prospero, J. M.: Trends in the solubility of iron in dust-dominated aerosols in the Equatorial Atlantic Trade Winds: The importance of iron speciation and sources, Geochem. Geophys. Geosyst., 11(1), in press, 2010. Tsuda, A., Takeda, S., Saito, H., Nishioka, J., Nojiri, Y., Kudo, I., Kiyosawa, H., Shiomoto, A., Imai, K., Ono, T., Shimamoto, A., Tsumune, D., Yoshimura, T., Aono, T., Hinuma, A., Kinugasa, M., Suzuki, K., Sohrin, Y., Noiri, Y., Tani, H., Deguchi, Y., Tsurushima, N., Ogawa, H., Fukami, K., Kuma, K., and Saino, T.: A mesoscale iron enrichment in the western Subarctic Pacific induces a large centric diatom bloom, Science, 300, 958–961, 2003. Turner, D. R. and Hunter, K. A.: The Biogeochemistry of Iron in Seawater, IUPAC Series on Analytical and Physical Chemistry of Environmental Systems, John Wiley and Sons Ltd., West Sussex, England, 396 pp., 2001. Twining, B. S., Baines, S. B., Fisher, N. S., and Landry, M. R.: Cellular iron contents of plankton during the Southern Ocean Iron Experiment (SOFeX), Deep-Sea Res., 51, 1827–1850, doi:10.1016/j.dsr.2004.08.007, 2004. Ussher, S. J., Worsfold, P. J., Achterberg, E. P., Laes, A., Blain, S., Laan, P., and de Baar, H. J. W.: Distribution and redox speciation of dissolved iron on the European continental margin, Limnol. Oceanogr., 52, 2530–2539, 2007. Vasconcelos, M., Leal, M. F. C., and van den Berg, C. M. G.: Influence of the nature of the exudates released by different marine algae on the growth, trace metal uptake, and exudation of Emiliania huxleyi in natural seawater, Mar. Chem., 77, 187–210, 2002. Venter, J. C., Remington, K., Heidelberg, J. F., Halpern, A. L., Rusch, D., Eisen, J. A., Wu, D. Y., Paulsen, I., Nelson, K. E., Nelson, W., Fouts, D. E., Levy, S., Knap, A. H., Lomas, M. W., Nealson, K., White, O., Peterson, J., Hoffman, J., Parsons, R., Baden-Tillson, H., Pfannkoch, C., Rogers, Y. H., and Smith, H. O.: Environmental genome shotgun sequencing of the Sargasso Sea, Science, 304, 66–74, doi:10.1126/science.1093857, 2004. Verdugo, P., Alldredge, A. L., Azam, F., Kirchman, D. L., Passow, U., and Santschi, P. H.: The oceanic gel phase: a bridge in the DOM-POM continuum, Mar. Chem., 92, 67–85, 2004. Vigenault, B. and Campbell, P. G. C.: Uptake of cadmium by freshwater green algae: Effects of pH and aquatic humic substances, J. Phycol., 41, 55–61, 2005. Vong, L., La\"es, A., and Blain, S.: Determination of iron-porphyrin-like complexes at nanomolar levels in seawater, Analytica Chimica Acta, 588, 237–244, doi:10.1016/j.aca.2007.1002.1007 2007. Vraspir, J. and Butler, A.: Chemistry of marine ligands and siderophores, Ann. Rev. Mar. Sci., 1, 43–63, 2009. Wagener, T., Guieu, C., Losno, R., Bonnet, S., and Mahowald, N.: Revisiting atmospheric dust export to the Southern Hemisphere ocean: Biogeochemical implications, Global Biogeochem. Cy., 22, GB2006, doi:10.1029/2007gb002984, 2008. Wang, W. X. and Dei, R. C. H.: Bioavailability of iron complexed with organic colloids to the cyanobacteria \textitSynechococcus and \textitTrichodesmium, Aquatic Microbial Ecology, 33, 247–259, 2003. Watson, A. J.: Iron limitation in the oceans, in: The biogeochemistry of iron in seawater, edited by: Turner, D. R., and Hunter, K. A., John Wiley & Sons Ltd., Chicester, 9–33, 2001. Weber, L., Völker, C., Oschlies, A., and Burchard, H.: Iron profiles and speciation of the upper water column at the Bermuda Atlantic Time-series Study site: a model based sensitivity study, Biogeosciences, 4, 689–706, 2007. Wells, M. L.: A neglected dimension, Nature, 391, 530–531, 1998. Wells, M. L., Trick, C. G., Cochlan, W. P., Hughes, M. P., and Trainer, V. L.: Domoic acid: The synergy of iron, copper, and the toxicity of diatoms, Limnol. Oceanogr., 50, 1908–1917, 2005. Willey, J. D., Kieber, R. J., Seaton, P. J., and Miller, C.: Rainwater as a source of Fe(II)-stabilizing ligands to seawater, Limnol. Oceanogr., 53, 1678–1684, 2008. Wolff, E. W., Fischer, H., Fundel, F., Ruth, U., Twarloh, B., Littot, G. C., Mulvaney, R., Rothlisberger, R., de Angelis, M., Boutron, C. F., Hansson, M., Jonsell, U., Hutterli, M. A., Lambert, F., Kaufmann, P., Stauffer, B., Stocker, T. F., Steffensen, J. P., Bigler, M., Siggaard-Andersen, M. L., Udisti, R., Becagli, S., Castellano, E., Severi, M., Wagenbach, D., Barbante, C., Gabrielli, P., and Gaspari, V.: Southern Ocean sea-ice extent, productivity and iron flux over the past eight glacial cycles, Nature, 440, 491–496, doi:10.1038/nature04614, 2006. Worms, I., Simon, D. F., Hassler, C. S., and Wilkinson, K. J.: Bioavailability of trace metals to aquatic microorganisms: importance of chemical, biological and physical processes on biouptake, Biochimie, 88, 1721–1731, doi:10.1016/j.biochi.2006.09.008, 2006. Wu, J. F., Boyle, E., Sunda, W., and Wen, L. S.: Soluble and colloidal iron in the olgotrophic North Atlantic and North Pacific, Science, 293, 847–849, 2001. Wu, J. F., Chung, S. W., Wen, L. S., Liu, K. K., Chen, Y. L. L., Chen, H. Y., and Karl, D. M.: Dissolved inorganic phosphorus, dissolved iron, and Trichodesmium in the oligotrophic South China Sea, Global Biogeochem. Cy., 17, doi:10.1029/2002GB001924, 2003. Ye, Y., Völker, C., and Wolf-Gladrow, D. A.: A model of Fe speciation and biogeochemistry at the Tropical Eastern North Atlantic Time-Series Observatory site, Biogeosciences, 6, 2041–2061, 2009. Yooseph, S., Sutton, G., Rusch, D. B., Halpern, A. L., Williamson, S. J., Remington, K., Eisen, J. A., Heidelberg, K. B., Manning, G., Li, W. Z., Jaroszewski, L., Cieplak, P., Miller, C. S., Li, H. Y., Mashiyama, S. T., Joachimiak, M. P., van Belle, C., Chandonia, J. M., Soergel, D. A., Zhai, Y. F., Natarajan, K., Lee, S., Raphael, B. J., Bafna, V., Friedman, R., Brenner, S. E., Godzik, A., Eisenberg, D., Dixon, J. E., Taylor, S. S., Strausberg, R. L., Frazier, M., and Venter, J. C.: The Sorcerer II Global Ocean Sampling expedition: Expanding the universe of protein families, PLoS. Biol., 5, 432–466, doi:10.1371/journal.pbio.0050016, 2007. Yoshida, T., Hayashi, K., and Ohmoto, H.: Dissolution of iron hydroxides by marine bacterial siderophore, Chem. Geol., 184, 1–9, 2002. Zhang, W. and Wang, W.-X.: Colloidal organic carbon and trace metal (Cd, Fe, and Zn) releases by diatom exudation and copepod grazing, Journal of Experimental Marine Biology and Ecology, 307, 17–34, 2004.