Modelling iodine in the ocean

Wadley, Martin R.; Stevens, David P.; Jickells, Tim; Hughes, Claire; Chance, Rosie; Hepach, Helmke; Carpenter, Lucy J.

doi:10.1002/essoar.10502078.1

Cited by 3 publications

(8 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…IO3is constantly replenished by the chemical oxidation of I -, so DIRM do not rely on other organisms for their substrate. IO3is typically scarce (0.45µM in seawater) 4 , so DIRM must compete with IO3reduction by chemical reductants and by inadvertent biological activity, such as by algae, that contribute to the relative depletion of IO3in those waters 7,61,65,69,70 . By analogy, perchlorate-reducing bacteria, which are common but sparse due to low natural abundance of perchlorate 71 , may provide further insight into the ecology of DIRM broadly.…”

Section: Significancementioning

confidence: 99%

Genetic and phylogenetic analysis of dissimilatory iodate-reducing bacteria identifies potential niches across the world’s oceans

Reyes-Umana

Henning

Lee

et al. 2020

Preprint

View full text Add to dashboard Cite

Iodine is oxidized and reduced as part of a biogeochemical cycle that is especially pronounced in the oceans, where the element naturally concentrates. The use of oxidized iodine in the form of iodate (IO3-) as an electron acceptor by microorganisms is poorly understood. Here, we outline genetic, physiological, and ecological models for dissimilatory IO3- reduction to iodide (I-) by a novel estuarine bacterium, Denitromonas iodocrescerans strain IR-12, sp. nov. Our results show that dissimilatory iodate reduction (DIR) by strain IR-12 is molybdenum-dependent and requires an IO3- reductase (idrA) and likely other genes in a mobile cluster with a conserved association across known and predicted DIR microorganisms (DIRM). Based on genetic and physiological data, IO3- is likely reduced to hypoiodous acid (HIO), which rapidly disproportionates into IO3- and iodide (I-), in a respiratory pathway that provides an energy yield equivalent to that of nitrate or perchlorate respiration. Consistent with the ecological niche expected of such a metabolism, idrA is enriched in the metagenome sequence databases of marine sites with a specific biogeochemical signature and diminished oxygen. Taken together, these data suggest that DIRM help explain the disequilibrium of the IO3-:I- concentration ratio above oxygen minimum zones and support a widespread iodine redox cycle mediated by microbiology.

show abstract

Section: Significancementioning

confidence: 99%

Genetic and phylogenetic analysis of dissimilatory iodate-reducing bacteria identifies potential niches across the world’s oceans

Reyes-Umana

Henning

Lee

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…In a companion paper Wadley et al (2020) develop an ocean iodine cycling model, with iodide production driven by primary productivity, and iodide oxidation to iodate linked to nitrification in the mixed layer. We use nitrogen fluxes derived from a global biogeochemical cycling model (Yool et al, 2007) to derive the spatial distribution of mixed layer ammonia oxidation.…”

Section: Modelling Iodine Cycling In the Oceanmentioning

confidence: 99%

“…Iodide is oxidised to iodate in association with the ammonia oxidation, with the same I:N:C ratio as associated with iodide production (Truesdale et al, 2001;Long et al, 2015). For full discussion of how the model was optimised for Ioxidation refer to Wadley et al (2020). The iodine cycling model is embedded within a circulation model of the upper ocean.…”

Section: Modelling Iodine Cycling In the Oceanmentioning

confidence: 99%

“…These results were interpolated to give the required proportion of ammonia oxidised in the mixed layer for each of our sensitivity runs, in which nitrification rates were perturbed by +10%, -10%, -22% and -44%. In the model a reduction in the nitrification rate results in a reduction in the oxidation of ammonia to nitrite, and a corresponding reduction in the oxidation of iodide to iodate (see Wadley et al, 2020 for details).…”

Section: Modelling Iodine Cycling In the Oceanmentioning

confidence: 99%

“…The primary aim of this study was to establish whether Ioxidation to IO 3 is associated with marine nitrification. Our objectives were to determine if IO 3 production occurs in cultures of marine ammonia-and nitrite-oxidising bacteria supplied with I -, determine the relative rates of IO 3 production and nitrification, and use an ocean iodine cycling model (Wadley et al, 2020) to establish how predicted future changes in marine nitrification could impact sea-surface iodide fields.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Iodate production in cultures of marine ammonia-oxidising bacteria: implications for future inorganic iodine distributions in the oceans

Hughes

Barton

Hepach

et al. 2020

Preprint

View full text Add to dashboard Cite

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 (IO) 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 IO. A significant increase in IO concentrations compared to media-only controls was observed in cultures of the ammonia-oxidising bacteria sp(Nm51) and (Nc10) supplied with 9-10 mM I, indicating I oxidation to IO. Cell-normalised production rates were 15.69 (±4.71) fmol IO cell d for sp., and 11.96 (±6.96) fmol IO cell d for , 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 ItoIO oxidation. If the link between ammonia and I oxidation observed here is representative, our ocean iodine cycling model predicts that decreases in marine nitrification under ocean acidification could lead to significantly higher sea surface I. A global sensitivity analysis suggests a 0.13 nM increase in sea surface I concentrations per percentage decrease in nitrification rate. In turn, this could result in increased O deposition to the sea surface and sea-air iodine emissions, with implications for atmospheric chemistry and air quality.

show abstract

Genetic and phylogenetic analysis of dissimilatory iodate-reducing bacteria identifies potential niches across the world’s oceans

et al. 2021

View full text Add to dashboard Cite

Iodine is oxidized and reduced as part of a biogeochemical cycle that is especially pronounced in the oceans, where the element naturally concentrates. The use of oxidized iodine in the form of iodate (IO3−) as an electron acceptor by microorganisms is poorly understood. Here, we outline genetic, physiological, and ecological models for dissimilatory IO3− reduction to iodide (I−) by a novel estuarine bacterium, Denitromonas sp. IR-12. Our results show that dissimilatory iodate reduction (DIR) by strain IR-12 is molybdenum-dependent and requires an IO3− reductase (idrA) and likely other genes in a mobile cluster with a conserved association across known and predicted DIR microorganisms (DIRM). Based on genetic and physiological data, we propose a model where three molecules of IO3− are likely reduced to three molecules of hypoiodous acid (HIO), which rapidly disproportionate into one molecule of IO3− and two molecules of iodide (I−), in a respiratory pathway that provides an energy yield equivalent to that of nitrate or perchlorate respiration. Consistent with the ecological niche expected of such a metabolism, idrA is enriched in the metagenome sequence databases of marine sites with a specific biogeochemical signature (high concentrations of nitrate and phosphate) and diminished oxygen. Taken together, these data suggest that DIRM help explain the disequilibrium of the IO3−:I− concentration ratio above oxygen-minimum zones and support a widespread iodine redox cycle mediated by microbiology.

show abstract

Modelling iodine in the ocean

Cited by 3 publications

References 42 publications

Genetic and phylogenetic analysis of dissimilatory iodate-reducing bacteria identifies potential niches across the world’s oceans

Genetic and phylogenetic analysis of dissimilatory iodate-reducing bacteria identifies potential niches across the world’s oceans

Iodate production in cultures of marine ammonia-oxidising bacteria: implications for future inorganic iodine distributions in the oceans

Genetic and phylogenetic analysis of dissimilatory iodate-reducing bacteria identifies potential niches across the world’s oceans

Contact Info

Product

Resources

About