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

Hughes, Claire; Barton, Eleanor; Hepach, Helmke; Chance, Rosie; Pickering, Matt; Hogg, Karen; Pommerening‐Röser, Andreas; Wadley, Martin R.; Stevens, David P.; Jickells, Timothy D.

doi:10.1016/j.marchem.2021.104000

Cited by 19 publications

(19 citation statements)

References 48 publications

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“…In our time-series data (Figure 9 and Supplementary Material Figure S2), nitrification is correlated with the reduction of iodate rather the oxidation of iodide, which appears to contradict the finding from studies with microbial cultures that ammonia oxidation is a sink for iodide (Hughes et al, 2021). However, despite the correlation, our results should not be taken to imply that nitrification is responsible for the increase of iodide.…”

Section: Fate Of Subsurface Iodidecontrasting

confidence: 99%

“…One suggestion is that the oxidation of iodide is connected with ammonium oxidation during nitrification. Hughes et al (2021) demonstrated that ammonium oxidising bacteria can mediate iodide oxidation to iodate during culture incubations with added excess iodide. Wadley et al (2020) built this process into their global model of iodine cycling where surface layer nitrification played a key role as a "fast" sink for iodide, especially in sub-tropical waters.…”

Section: Fate Of Subsurface Iodidementioning

confidence: 99%

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Speciation of dissolved inorganic iodine in a coastal fjord: a time-series study from Bedford Basin, Nova Scotia, Canada

2023

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We report a long-term (4.5 year) time-series with weekly resolution of iodide and iodate measurements made at 4 depths within the Bedford Basin: a 70 m deep, seasonally stratified, coastal fjord located near Halifax, Nova Scotia, Canada. The subsurface data (60 m) reveal strong inverse correlations of both iodide and total dissolved iodine (TDI) with dissolved oxygen and indicate that there is in-situ reduction of iodate in subsurface waters (in the presence of oxygen) as well as an additional external source of iodide from the remineralization of sinking organic matter, a flux from sediments, or both. Surface water (<10 m) iodide concentrations increase gradually from spring (70 nmol L-1) through fall (120-150 nmol L-1) and are not well represented by the current empirical parameterizations used to predict surface water iodide levels globally. The vertical gradient of iodide between subsurface and surface waters increases over the summer as a result of subsurface processes and, together with diapycnal mixing, may contribute to the seasonal accumulation of iodide in surface water. Examination of a global surface water iodide data compilation reveals an inverse relationship with subsurface oxygen concentrations which suggests that subsurface remineralization and sediment-water fluxes coupled with vertical mixing may also contribute to surface water iodide variability on a global scale.

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Section: Fate Of Subsurface Iodidecontrasting

confidence: 99%

Section: Fate Of Subsurface Iodidementioning

confidence: 99%

Speciation of dissolved inorganic iodine in a coastal fjord: a time-series study from Bedford Basin, Nova Scotia, Canada

2023

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“…(2020) found the best fit to the measured distributions when it was assumed that iodide oxidation was correlated with the first step in nitrification: ammonia oxidation. This is consistent with recent data showing that some ammonia oxidizing bacteria can oxidize iodide, while others possess multicopper oxidases (similar to ammonium monooxygenase) that oxidize iodide (Hughes et al., 2021; Long et al., 2015; Truesdale et al., 2001; Yeager et al., 2017). Ammonia oxidation is inhibited at high light intensities and is slow in permanently stratified tropical waters (Horak et al., 2018), so iodide oxidation may also be light inhibited as well.…”

Section: Discussionsupporting

confidence: 90%

Meridional Survey of the Central Pacific Reveals Iodide Accumulation in Equatorial Surface Waters and Benthic Sources in the Abyssal Plain

Moriyasu

Bolster

Kadko

et al. 2023

Global Biogeochemical Cycles

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The distributions of iodate and iodide were measured along the GEOTRACES GP15 meridional transect at 152°W from the shelf of Alaska to Papeete, Tahiti. The transect included oxygenated waters near the shelf of Alaska, the full water column in the central basin in the North Pacific Basin, the upper water column spanning across seasonally mixed regimes in the north, oligotrophic regimes in the central gyre, and the equatorial upwelling. Iodide concentrations are highest in the permanently stratified tropical mixed layers, which reflect accumulation due to light‐dependent biological processes, and decline rapidly below the euphotic zone. Vertical mixing coefficients (Kz), derived from complementary 7Be data, enabled iodide oxidation rates to be estimated at two stations. Iodide half‐lives of 3–4 years show the importance of seasonal mixing processes in explaining north‐south differences in the transect, and also contribute to the decrease in iodide concentrations with depth below the mixed layer. These estimated half‐lives are consistent with a recent global iodine model. No evidence was found for significant inputs of iodine from the Alaskan continental margin, but there is a significant enrichment of iodide in bottom waters overlying deep sea sediments from the interior of the basin.

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“…As total iodine in surface ocean waters is lower by a few percent compared to deep waters (Wong, 1991), the decomposition of organic-iodine leads to some Irelease, which may be oxidized to IO − 3 by ammonia-oxidizing bacteria (Hughes et al, 2021). This is similar to release and oxidation of NH + 4 to NO − 3 from particulate organic matter in deep waters that results in an increase of NO − 3 concentration with depth (recycled element profile).…”

Section: Hoi and I 2 Formation Leads To Organic Iodinementioning

confidence: 99%

“…Thus, other oxidants are required to initiate abiotic iodide oxidation, and Iis a known sink for O 3 . Biotic iodide oxidation has received much interest with one report showing conversion of iodide to iodate (Hughes et al, 2021). Iodate reduction can occur with common reductants (e.g., sulfide, Fe 2+ ), and various organisms that decompose organic matter using iodate as the electron acceptor.…”

Section: Introductionmentioning

confidence: 99%

Review on the physical chemistry of iodine transformations in the oceans

Luther

2023

Front. Mar. Sci.

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The transformation between iodate (IO3−), the thermodynamically stable form of iodine, and iodide (I-), the kinetically stable form of iodine, has received much attention because these species are often dependent on the oxygen concentration, which ranges from saturation to non-detectable in the ocean. As suboxic conditions in the ocean’s major oxygen minimum zones indicate that IO3− is minimal or non-detectable, the incorporation of IO3− into carbonate minerals has been used as a redox proxy to determine the O2 state of the ocean. Here, I look at the one and two electron transfers between iodine species with a variety of oxidants and reductants to show thermodynamics of these transformations. The IO3− to IO2− conversion is shown to be the controlling step in the reduction reaction sequence due to thermodynamic considerations. As IO3− reduction to IO2− is more favorable than NO3− reduction to NO2− at oceanic pH values, there is no need for nitrate reductase for IO3− reduction as other reductants (e.g. Fe2+, Mn2+) and dissimilatory IO3− reduction by microbes during organic matter decomposition can affect the transformation. Unfortunately, there is a dearth of information on the kinetics of reductants with IO3−; thus, the thermodynamic calculations suggest avenues for research. Conversely, there is significant information on the kinetics of I- oxidation with various oxygen species. In the environment, I- oxidation is the controlling step for oxidation. The oxidants that can lead to IO3− are reactive oxygen species with O3 and •OH being the most potent as well as sedimentary oxidized Mn, which occurs at lower pH than ocean waters. Recent work has shown that iodide oxidizing bacteria can also form IO3−. I- oxidation is more facile at the sea surface microlayer and in the atmosphere due to O3.

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

Cited by 19 publications

References 48 publications

Speciation of dissolved inorganic iodine in a coastal fjord: a time-series study from Bedford Basin, Nova Scotia, Canada

Speciation of dissolved inorganic iodine in a coastal fjord: a time-series study from Bedford Basin, Nova Scotia, Canada

Meridional Survey of the Central Pacific Reveals Iodide Accumulation in Equatorial Surface Waters and Benthic Sources in the Abyssal Plain

Review on the physical chemistry of iodine transformations in the oceans

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