Iodate reduction by Isochrysis galbana is relatively insensitive to de-activation of nitrate reductase activity—are phytoplankton really responsible for iodate reduction in seawater?

Waite, Tim J.; Truesdale, Victor W.

doi:10.1016/s0304-4203(03)00013-6

Cited by 49 publications

(46 citation statements)

References 39 publications

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“…The magnitude of one of these changes ranks with the 0.20 mol L Ϫ1 target suggested by Truesdale and Bailey (2002) as unequivocal proof of iodate reduction and is therefore important. (Incidentally, the cultures contained nitrate under conditions similar to those used by Truesdale 1978a, Butler et al 1981, andWaite and press, yet the yields of iodide are very much greater.) The losses of iodate were between 0.15 and 0.30 mol L Ϫ1 for all but the cultures of Tetraselmis sp.…”

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confidence: 86%

“…We note also that, using Michaelis-Menten kinetics, Truesdale and Bailey (2002) showed that the effectiveness of the competition between nitrate and iodate would be far less affected by changes in nitrate concentration than might first appear. Finally, Waite and Truesdale (2003) have shown that deactivation of nitrate reductase, the enzyme in phytoplankton hitherto thought to facilitate iodate reduction, left I. galbana's iodate-reducing ability unaffected.…”

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confidence: 99%

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On the relative constancy of iodate and total‐iodine concentrations accompanying phytoplankton blooms initiated in mesocosm experiments in Antarctica

Truesdale

Kennedy

Agustı́

et al. 2003

Limnology & Oceanography

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The integrated iodate and total-iodine concentrations accompanying accelerated growth of natural phytoplankton in eight 14-m deep mesocosm experiments did not vary significantly. Growth was induced by the addition of nutrients, while light irradiance was controlled by neutral density screens. These measures resulted in a range of particulate organic carbon concentrations of between 13 and 220 mol L Ϫ1 , that is, covering some that are well in excess of blooms generally found in the natural environment. This, together with most earlier results obtained from phytoplankton culturing and much hydrographic survey, is used as an opportunity to question whether phytoplankton growth can be the cause of iodate reduction in seawater.In oxic seawater, iodine exists in dissolved and particulate forms (Wong 1991) at mol L Ϫ1 and pmol L Ϫ1 concentrations, respectively. It is a biointermediate element incorporated into phytoplankton biomass in near-surface waters and regenerated diagenetically. Despite a slight assimilation by phytoplankton, the major change observed in seawater is the interconversion between iodate and iodide (chemical reduction) in near-surface waters (see Truesdale et al. 2000). Iodate is predominant in deep waters (Tsunogai 1971) where the low iodide concentrations are similar to those predicted by the decomposition of organic material sinking from the near-surface waters (Truesdale 1994). Attempts to explain iodate reduction in oxic seawater have linked it to phytoplankton growth, microbial respiration (Truesdale and Bailey 2002), photochemistry (Spokes and Liss 1996), and sediment-water interaction. In the case of phytoplankton the reduction has largely been assumed to be dissimilatory.The most popular explanation for iodate reduction, that involving phytoplankton, received early support from good correlations between iodate and nutrient concentrations in the permanently stratified water column of the tropical and subtropical oceans (Truesdale et al. 2000). However, a sustained reduction of about the same amount of 0.2 mol L Ϫ1 AcknowledgmentsThis mesocosm research is part of the ESEPAC program funded by the Spanish National Antarctic Programme (CICYT ANT97-0273). Thanks are due to Paul Kennedy for collecting the samples. We thank C. Cordón, commander of the R/V Hespérides, the crew, the UGBO personnel involved in the experiment, and all scientists participating in the ESEPAC experiment for their contribution. T.J.W. was funded by NERC studentship 04/99/MS214.

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confidence: 86%

mentioning

confidence: 99%

On the relative constancy of iodate and total‐iodine concentrations accompanying phytoplankton blooms initiated in mesocosm experiments in Antarctica

Truesdale

Kennedy

Agustı́

et al. 2003

Limnology & Oceanography

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“…However, significant quantities of iodide, up to 0.3 μM, are observed at the surface 16,82,83) . It is widely speculated that this apparent disequilibrium is caused by the biological reduction of iodate to iodide, and marine microorganisms such as bacteria 24,28,84) and phytoplanktons 19,88,95) may play significant roles in the process. Iodide is also the dominant form of iodine in deep oxygenated water 64) , anoxic basins 20,29,30,50,85,94,96) , and porewater of marine sediment 31,44,60,66) .…”

Section: Reduction Of Iodatementioning

confidence: 99%

Microbial Contribution to Global Iodine Cycling: Volatilization, Accumulation, Reduction, Oxidation, and Sorption of Iodine

2008

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Iodine is an essential trace element for humans and animals because of its important role as a constituent of thyroid hormones. If the anthropogenic iodine-129 ( 129 I, half-life: 1.6×10 7 years), which is released from nuclear facilities into the environment and has a long half-life, participates in the biogeochemical cycling of iodine, it potentially accumulates in the human thyroid gland and might cause thyroid cancer. Therefore, it is necessary to obtain better information on the behavior of iodine in the environment for accurate safety assessments of 129 I. Major pathways of iodine cycling are the volatilization of organic iodine compounds into the atmosphere, accumulation of iodine in living organisms, oxidation and reduction of inorganic iodine species, and sorption of iodine by soils and sediments. Considerable geochemical evidence has indicated that these processes are influenced or controlled by microbial activities, although the precise mechanisms involved are still unclear. This review summarizes current knowledge on interactions between microorganisms and iodine, with special emphasis on newly isolated bacteria possibly contributing to the cycling of iodine on a global scale.

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“…Porém, isso não é observado, pois o iodeto é encontrado em águas superficiais em concentração maior do que o esperado, podendo até chegar a 50% do iodo total (Wong 1995, Waite & Truesdale 2003. A elevada concentração de iodeto em água superficial tem indicado a participação do iodo em processos mediados por micro-organismos (Rebello et al 1990, Edwards & Truesdale 1997.…”

Section: Estudo Do Equilíbrio Químico Do Iodo Na áGua Do Marunclassified

“…Mesmo durante os 23 dias de incubação, o iodato-131 nas amostras filtradas sofreu conversão em torno de 5% de iodato para iodeto. Esse lapso de tempo para começar a formação do iodeto a partir do iodato foi mencionado por Waite & Truesdale (2003) que reportaram um tempo de retardo de 10 dias para começarem a observar a formação de iodeto durante estudos de incubação de iodato em culturas de fitoplâncton. Diferentemente do que acontece com amostras incubadas com iodeto, houve a redução de aproximadamente 50% do iodato-131 adicionados na amostra não filtrada para iodeto-131, enquanto na amostra que sofreu processo de filtração houve conversão em torno de 25%.…”

Section: Estudo Do Equilíbrio Químico Do Iodo Na áGua Do Marunclassified

Breve revisão sobre os estudos realizados com radiotraçadores artificiais para a obtenção de parâmetros físico-químicos em matrizes ambientais na Floresta Experimental de Itacuruçá/RJ

Bernedo¹,

Machado²,

Canesin³

et al. 2013

Geochim. Bras.

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Iodate reduction by Isochrysis galbana is relatively insensitive to de-activation of nitrate reductase activity—are phytoplankton really responsible for iodate reduction in seawater?

Cited by 49 publications

References 39 publications

On the relative constancy of iodate and total‐iodine concentrations accompanying phytoplankton blooms initiated in mesocosm experiments in Antarctica

On the relative constancy of iodate and total‐iodine concentrations accompanying phytoplankton blooms initiated in mesocosm experiments in Antarctica

Microbial Contribution to Global Iodine Cycling: Volatilization, Accumulation, Reduction, Oxidation, and Sorption of Iodine

Breve revisão sobre os estudos realizados com radiotraçadores artificiais para a obtenção de parâmetros físico-químicos em matrizes ambientais na Floresta Experimental de Itacuruçá/RJ

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