The effect of ocean acidification on organic and inorganic speciation of trace metals

• Published in: Environmental Science & Technology
• Main Authors: Stockdale, A, Tipping, E, Lofts, S, Mortimer, RJG
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Chemical Society 2016
• Subjects: Ocean acidification
• Online Access: http://irep.ntu.ac.uk/id/eprint/26842/; http://irep.ntu.ac.uk/id/eprint/26842/1/PubSub4179_Mortimer.pdf; https://doi.org/10.1021/acs.est.5b05624

Rising concentrations of atmospheric carbon dioxide are causing acidification of the oceans. 20 This results in changes to the concentrations of key chemical species such as hydroxide, 21 carbonate and bicarbonate ions. These changes will affect the distribution of different forms 22 of trace metals. Using IPCC data for pCO2 and pH under four future emissions scenarios (to 23 the year 2100) we use a chemical speciation model to predict changes in the distribution of 24 organic and inorganic forms of trace metals. Under a scenario where emissions peak after 25 the year 2100, predicted free ion Al, Fe, Cu and Pb concentrations increase by factors of up 26 to approximately 21, 2.4, 1.5 and 2.0 respectively. Concentrations of organically complexed 27 metal typically have a lower sensitivity to ocean acidification induced changes. 28 Concentrations of organically-complexed Mn, Cu, Zn and Cd fall by up to 10%, while those 29 of organically-complexed Fe, Co and Ni rise by up to 14%. Although modest, these changes 30 may have significance for the biological availability of metals given the close adaptation of 31 marine microorganisms to their environment.