Oxidation of iodide to iodate by cultures of marine ammonia-oxidising bacteria

Hughes, Claire, Barton, Eleanor, Hepach, Helmke, Chance, Rosie, Pickering, Matthew D., Hogg, Karen, Pommerening-Röser, Andreas, Wadley, Martin R., Stevens, David P. and Jickells, Tim D. (2021) Oxidation of iodide to iodate by cultures of marine ammonia-oxidising bacteria. Marine Chemistry, 234. ISSN 0304-4203

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Abstract

Reaction with iodide (I−) at the sea surface is an important sink for atmospheric ozone, and causes sea-air emission of reactive iodine which in turn drives further ozone destruction. To incorporate this process into chemical transport models, improved understanding of the factors controlling marine iodine speciation, and especially sea-surface iodide concentrations, is needed. The oxidation of I− to iodate (IO3−) is the main sink for oceanic I−, but the mechanism for this remains unknown. We demonstrate for the first time that marine nitrifying bacteria mediate I− oxidation to IO3−. A significant increase in IO3− concentrations compared to media-only controls was observed in cultures of the ammonia-oxidising bacteria Nitrosomonas sp. (Nm51) and Nitrosoccocus oceani (Nc10) supplied with 9–10 mM I−, indicating I− oxidation to IO3−. Cell-normalised production rates were 15.69 (±4.71) fmol IO3− cell−1 d−1 for Nitrosomonas sp., and 11.96 (±6.96) fmol IO3− cell−1 d−1 for Nitrosococcus oceani, and molar ratios of iodate-to-nitrite production were 9.2 ± 4.1 and 1.88 ± 0.91 respectively. Preliminary experiments on nitrite-oxidising bacteria showed no evidence of I− to IO3− oxidation. If the link between ammonia and I− oxidation observed here is representative, our ocean iodine cycling model predicts that future changes in marine nitrification could alter global sea surface I− fields with potential implications for atmospheric chemistry and air quality.

Item Type: Article
Faculty \ School: Faculty of Science > School of Mathematics
Faculty of Science > School of Environmental Sciences
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Depositing User: LivePure Connector
Date Deposited: 24 Jun 2021 00:11
Last Modified: 22 Jul 2021 00:06
URI: https://ueaeprints.uea.ac.uk/id/eprint/80321
DOI: 10.1016/j.marchem.2021.104000

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