Oceanography The Official Magazine of
The Oceanography Society
Volume 22 Issue 04

View Issue TOC
Volume 22, No. 4
Pages 72 - 85


Effect of Ocean Acidification on the Speciation of Metals in Seawater

By Frank J. Millero , Ryan Woosley , Benjamin DiTrolio, and Jason Waters 
Jump to
Article Abstract Citation References Copyright & Usage
Article Abstract

Increasing atmospheric CO2 over the next 200 years will cause the pH of ocean waters to decrease further. Many recent studies have examined the effect of decreasing pH on calcifying organisms in ocean waters and on other biological processes (photosynthesis, nitrogen fixation, elemental ratios, and community structure). In this review, we examine how pH will change the organic and inorganic speciation of metals in surface ocean waters, and the effect that it will have on the interactions of metals with marine organisms. We consider both kinetic and equilibrium processes. The decrease in concentration of OH– and CO32– ions can affect the solubility, adsorption, toxicity, and rates of redox processes of metals in seawater. Future studies are needed to examine how pH affects the interactions of metals complexed to organic ligands and with marine organisms.


Millero, F.J., R. Woosley, B. DiTrolio, and J. Waters. 2009. Effect of ocean acidification on the speciation of metals in seawater. Oceanography 22(4):72–85, https://doi.org/10.5670/oceanog.2009.98.


Baes, C.F., and R.E. Mesmer. 1976. The Hydrolysis of Cations. John Wiley & Sons Inc., 512 pp.

Bielski, B.H. 1978. Re-evaluations of the spectra and kinetic properties of HO2 and O2 free radicals. Photochemical Photobiology 28:645–649. 

Brand, L.E. 1991. Minimum iron requirements of marine phytoplankton and the implications for the biogeochemical control of new production. Limnology and Oceanography 36(8):1,756–1,771.

Brand, L.E., W.G. Sunda, and R.R.L. Guillard. 1986. Reduction of marine phytoplankton reproduction rates by copper and cadmium. Journal of Experimental Marine Biology and Ecology 96:225–250.

Breibarth E., R.J. Bellerby, C.C. Neill, M.V. Ardelan, M. Meyerhöfer, E. Zöllner, P.L. Croot, and U. Riebesell. 2009. Ocean acidification affects iron speciation in seawater. Biogeosciences Discussions. Available online at: http://www.biogeosciences-discuss.net/6/6781/2009/bgd-6-6781-2009.pdf (accessed October 21, 2009).

Bruland, K.W. 1989. Complexation of zinc by natural organic ligands in the central North Pacific. Limnology and Oceanography 34:269–285.

Bruland, K.W. 1992. Complexation of cadmium by natural organic ligands in the central North Pacific. Limnology and Oceanography 37:1,008–1,017.

Bruland, K.W., J.R. Donat, and D.A. Hutchins. 1991. Interactive influences of bioactive trace metals on biological production in oceanic waters. Limnology and Oceanography 36:1,555–1,577.

Byrne, R.H. 2002. Inorganic speciation of dissolved elements in seawater: The influence of pH on concentration ratios. Geochemical Transactions 3:11–16.

Byrne, R.H., L.R. Kump, and K.J. Cantrell.1988. The influence of temperature and pH on trace metal speciation in seawater. Marine Chemistry 25:163–181.

Caldeira, K., and M.E. Wickett. 2003. Oceanography: Anthropogenic carbon and ocean pH. Nature 425:365.

Cantrell, K.J., and R.H. Byrne. 1987. Rare earth complexation by carbonate and oxalate ions. Geochimica et Cosmochimica Acta 51(3):597–605.

Capodaglio, G., K.H. Coale, and K.W. Bruland. 1990. Lead Speciation in surface waters of the eastern North Pacific. Marine Chemistry 29:221–233.

Casas, A.M., and E.A. Crecelius. 1994. Relationship between acid volatile sulfide and the toxicity of zinc, lead and copper in marine sediments. Environmental Toxicology and Chemistry 13(3):529–536.

Coale, K.H., and K.W. Bruland. 1988. Copper complexation in the Northeast Pacific. Limnology and Oceanography 33:1,084–1,101.

Crist, R.H., K. Oberholser, D. Schwartz, J. Marzoff, D. Ryder, and D.R. Crist.1988. Interactions of metals and protons with algae. Environmental Science and Technology 22:755–760.

Croot, P.L., J.W. Moffett, and G.W. Luther III. 1999. Polarographic determination of half-wave potentials for copper-organic complexes in seawater. Marine Chemistry 67:219–232.

Davies, A.G. 1990. Taking a cool look at iron. Nature 345:114–115.

Dittmar, T., and J. Paeng. 2009. A heat-induced molecular signature in marine dissolved organic matter. Nature Geoscience 2:175–179.

Donat, J.R., and C.M.G. van den Berg. 1992. A new cathodic stripping voltammetric method for determining organic copper complexation in seawater. Marine Chemistry 38:69–90.

Ellwood, M.J., and C.M.G. van den Berg. 2001. Determination of organic complexation of cobalt in seawater by cathodic stripping voltammetry. Marine Chemistry 75(1–2):33–47.

Feely, R.A., C.L. Sabine, M. Hernandez-Ayon, D. Lanson, and B. Hales. 2008. Evidence for upwelling of “acidified” water onto the continental shelf. Science 320:1,490–1,492.

Gattuso, J.-P., M. Frankignoulle, I. Bourge, S. Romaine, and R.W. Buddemeier. 1998. Effect of calcium carbonate saturation of seawater on coral calcification. Global and Planetary Change 18(1–2):37–46.

Gledhill, M., and C.M.G. van den Berg. 1994. Determination of complexation of iron(III) with natural organic complexing ligands in seawater using cathodic stripping voltammetry. Marine Chemistry 47:41–54.

Goldstone, J.V., and B.M. Voelker. 2000. Chemistry of superoxide radical in seawater: CDOM associated sink of superoxide in coastal waters. Environmental Science and Technology 34:1,043–1,048.

Gonzalez-Davila, M., J. Santana-Casiano, M. Perez-Pena, and F.J. Millero. 1995. Binding of Cu(II) to the surface and exudates of the alga Dunaliella tertiolecta in seawater. Environmental Science and Technology 29:289–301.

Hering, J.G., W.G. Sunda, R.L. Ferguson, and F.M.M. Morel. 1987. A field comparison of two methods for the determination of copper complexation: Bacterial bioassay and fixed-potential amperometry. Marine Chemistry 20:299–312.

Hofmann, A.F., F.J.R. Meysman, K. Soetaert, and J. Middleburg. 2009. Factors governing the pH in a heterotrophic, turbid, tidal estuary. Biogeosciences Discussion 6:197–240.

Kleypas, J.A., R.W. Buddemeier, D. Archer, J-P. Gattuso, C. Langdon, and B.N. Opdyke. 1999. Geochemical consequences of increased atmospheric carbon dioxide on coral reefs. Science 284:118–120.

Kramer, C.J.M., and J.C. Duinker. 1984. Complexation capacity and conditional stability constants for copper of sea and estuarine waters, sediment extracts and colloids. Pp. 217–288 in Complexation of Trace Metals in Natural Waters. C.J.M. Kramer and J.C. Duinker, eds, Nijhoff/Junk, The Hague, The Netherlands.

Landry, M.R, R.T. Barber, R.R. Bidigare, F. Chai, K.H. Coale, H.G. Dam, M.R. Lewis, S.T. Lindley, J.J. McCarthy, M.R. Roman, and others. 1998. Iron and grazing constraints on primary production in the central equatorial Pacific: An EqPac synthesis. Limnology and Oceanography 42:405–418.

Langdon, C., W.S. Broecker, D.E. Hammond, E. Glenn, K. Fitzsimmons, S.G. Nelson, T.-H. Peng, I. Hajdas, and G. Bonani. 2003. Effect of elevated CO2 on the community metabolism of an experimental coral reef. Global Biogeochemical Cycles 17:1011, doi:10.1029/2002GB001941.

Liu, X., and F.J. Millero. 2002. The solubility of iron in seawater. Marine Chemistry 77:43–54.

Louis, Y., C. Garnier, V. Lenoble, D. Omanovic, S. Mounier, and I. Pizeta. 2009. Characterization and modelling of marine dissolved organic matter interactions with major and trace cations. Marine and Environmental Research 67:100–107.

Martin, J.H. 1990. Glacial-interglacial CO2 change: The iron hypothesis. Paleoceanography 5(1):1–13.

Martin, J.H., and S.E. Fitzwater. 1988. Iron deficiency limits phytoplankton growth in the north-east Pacific subarctic. Nature 331:341–343.

Millero, F.J. 1987. Estimate of the life time of superoxide in seawater. Geochimica et Cosmochimica Acta 51:351-353. 

Millero, F.J. 1992. Stability constants for the formation of rare earth inorganic complexes of a function of ionic strength. Geochimica et Cosmochimica Acta 56:3,123–3,132.

Millero, F.J. 2001a. Physical Chemistry of Natural Waters. Wiley-Interscience, NY. 654 pp.

Millero, F.J. 2001b. Speciation of metals in natural water. Geochemical Transactions 2(8): 56–64.

Millero, F.J., and D.J. Hawke. 1992. Ionic interactions of divalent metals in natural waters. Marine Chemistry 40:19–48.

Millero, F.J., and D. Pierrot. 1998. A chemical model for natural waters. Aquatic Geochemistry 4:153–199.

Millero, F.J., and D. Pierrot. 2002. Speciation of metals in natural waters. Pp. 193–220 in Chemistry of Marine Water and Sediments. A. Gianguzza, E. Pellizzetti, and S. Sammartano, eds, Springer-Verlag, Berlin.

Millero, F.J., T. Graham, F. Huang, H. Bustos, and D. Pierrot. 2006. Dissociation constants for carbonic acid in seawater as a function of temperature and salinity. Marine Chemistry 100:80–94.

Millero, F.J., V.K. Sharma, and B. Karn. 1991. The rate of reduction of Cu(II) with hydrogen peroxide in seawater. Marine Chemistry 36:71–83.

Millero, F.J., S. Sotolongo, and M. Izaguirre. 1987. The kinetics of oxidation of Fe(II) in seawater. Geochimica et Cosmochimica Acta 51:793–801.

Millero, F.J., W. Yao, and J. Aicher. 1995. The speciation of iron(II) and (III) in natural waters. Marine Chemistry 50:21–39.

Moffett, J.W., and R.G. Zika. 1983. Oxidation kinetics of Cu(I) in seawater: Implications for its existence in the marine environment. Marine Chemistry 13:39–251.

Moffett, J.W., and R.G. Zika. 1987. Solvent extraction of copper acetylacetonate in studies of copper(II) speciation in seawater. Marine Chemistry 21:301–313.

Morel, F.M.M., A.J. Milligan, and M.A. Saito. 2003. Marine bioinorganic chemistry: The role of trace metals in the oceanic cycles of major nutrients. Treatise on Geochemistry 6:113–143. 

Orr, J.C., V.J. Fabry, O. Aumont, L. Bopp, S.C. Doney, R.A. Feely, A. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, and others. 2005. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437:681–686.

Paytan, A., R.M. Mackey, Y. Chen, I.D. Lima, S.C. Doney, N. Mahowald, R. Labiosa, and A.F. Post. 2009. Toxicity of atmospheric aerosols on marine phytoplankton. Proceedings of the National Academy of Sciences of the United States of America 106:4,601–4,605.

Pitzer, K.S. 1991. Ion interaction approach: Theory and data collection. Pp. 75–153 in Activity Coefficients in Electrolyte Solutions, 2nd ed. CRC Press, Boca Raton, FL.

Rich, H.W., and F.M.M. Morel. 1990. Availability of well-defined iron colloids to the marine diatom Thalassiosira weissflogii. Limnology and Oceanography 35:652–662.

Ritchie, J.D., and E.M. Perdue. 2003. Proton-binding study of standard and reference fulvic acids, humic acids, and natural organic matter. Geochimica et Cosmochimica Acta 67:85–96.

Rose, A.L., and T.D. Waite. 2005. Reduction of organically complexed ferric iron by superoxide in a simulated natural water. Environmental Science and Technology 39:2,645–2,650.

Rose, A.L., E.A. Webb, T.D. Waite, and J.W. Moffett. 2008. Measurement and implications of nonphotochemically generated superoxide in the Equatorial Pacific Ocean. Environmental Science and Technology 42:2,387–2,393.

Rue, E.L., and K.W. Bruland. 1995. 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. Marine Chemistry 50:17–138.

Saito, M.A., and J.W. Moffet. 2001. Complexation of cobalt by natural organic ligands in the Sargasso Sea as determined by a new high-sensitivity electrochemical cobalt speciation method suitable for open ocean water. Marine Chemistry 79(1–2):49–68.

Schreiber, D.R., A.S. Gordon, and F.J. Millero. 1985. The toxicity of copper to the marine bacterium Vibrio alginolyticus. Canadian Journal of Microbiology 31:83–87.

Sharma, V.K., and F.J. Millero. 1988. The oxidation of Cu(I) with H2O2 in natural waters. Geochimica et Cosmochimica Acta 53:2,269–2,276.

Sleighter, R.L., and P.G. Hatcher. 2007. The application of electrospray ionization coupled to ultrahigh resolution mass spectrometry for the molecular characterization of natural organic matter. Journal of Mass Spectrometry 42:559–574.

Steemann Nielsen, E., and S. Wium-Anderson. 1970. Copper ions as poison in the sea and in freshwater. Marine Biology 6:93–97.

Sunda, W.G., and R.L. Ferguson. 1983. Sensitivity of natural bacterial communities to additions of copper and to cupric ion activity: A bioassay of copper complexation in seawater. Pp. 871–891 in Trace Metals in Seawater. C.S. Wong, E. Boyle, K.W. Bruland, J.D. Burton, and E.D. Goldberg, eds, Plenum, New York.

Sunda, W.G., and A.K. Hanson.1987. Measurement of free cupric ion concentration in seawater by a ligand competition technique involving copper sorption onto C18 SEP-PAK cartridges. Limnology and Oceanography 32:537–551.

Sunda, W.G., and S.A. Huntsman. 1992. Feedback interactions between zinc and phytoplankton in seawater. Limnology and Oceanography 37:25–40.

Sunda, W.G., D. Klaveness, and A.V. Palumbo. 1984. Bioassays of cupric ion activity and copper complexation. Pp. 399–409 in Complexation of Trace Metals in Natural Waters. C.J.M. Kramer and J.C. Duinker, eds, Nijhoff/Junk, The Hague, The Netherlands.

Turner, D.R., M. Whitfield, and A.G. Dickson. 1981. The equilibrium speciation of dissolved components of freshwater and seawater at 25°C and 1 atm pressure. Geochimica et Cosmochimica Acta 44:855–881.

van den Berg, C.M.G. 1982. Determination of copper complexation with natural organic ligands in seawater by equilibration with MnO2. II. Experimental procedures and application to surface seawater. Marine Chemistry 11:323–342.

van den Berg, C.M.G. 1984. Determination of the complexing capacity and conditional stability constants of complexes of copper(II) with natural organic ligands in seawater by cathodic stripping voltammetry of copper-catechol complexions. Marine Chemistry 15:1,268–1,274.

van den Berg, C.M.G., and M. Nimmo. 1987. Determination of interactions of nickel with dissolved organic material in seawater using cathodic stripping voltammetry. Science of the Total Environment 60:185–195.

Voelker, B.M., D.L. Sedlak, and O.C. Zafiriou. 2000. Chemistry of superoxide radical in seawater: Reactions with organic Cu complexes. Environmental Science and Technology 34(6):1,036–1,042.

Wilde, K.L., J.L. Stauber, S.J. Markich, N.M. Franklin, and P.L. Brown. 2006. The effect of pH on the uptake and toxicity of copper and zinc in a tropical freshwater alga (Chlorella sp.). Archives of Environmental Contamination and Toxicology 51:174–185.

Woosley, R., and F.J. Millero. In press. The hydrolysis of Al(III) in NaCl solutions: A model for M(II), M(III) and M(IV) ions. Aquatic Geochemistry.

Wu, J., and G.W. Luther. 1995. Complexation of Fe(III) by natural organic ligands in the Northwest Atlantic Ocean by a competitive ligand equilibration method and a kinetic approach. Limnology and Oceanography 50:119–177.

Zafiriou, O.C., B.M. Voelker, and D.L. Sedlak. 1998. Chemistry of the superoxide radical (O2) in seawater: Reactions with inorganic copper complexes. Journal of Physical Chemistry A 102(23):693–700.

Zhang, J., C.M.G. van den Berg, and R. Wollast. 1990. The determination of interactions of cobalt(II) with organic compounds in seawater using cathodic stripping voltammetry. Marine Chemistry 28:285–300.

Zika, R.G., J.W. Moffett, W.J.C. Petasne, and E.S. Saltzman. 1985. Spatial and temporal variations of hydrogen peroxide in Gulf of Mexico waters. Geochimica et Cosmochimica Acta 49:1,173–1,184.

Copyright & Usage

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.