Abiotic reaction of iodate with sphagnum peat and other natural organic matter

Steinberg, Spencer M.; Kimble, G.; Schmett, G. T.; Emerson, David R.; Turner, M. F.; Rudin, Mark

doi:10.1007/s10967-008-0728-1

Cited by 43 publications

(24 citation statements)

References 20 publications

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“…These authors suggested that the natural organic matter (NOM) was responsible for this irreversible uptake. Indeed, as previously shown by Reiller and Moulin (2003), Schlegel et al (2006) and Steinberg et al (2008), the iodination of the organic matter leads to the formation of covalent bonds, thus, to an immobilisation of iodine. Such a mechanism is capable of explaining the retardation of the iodide migrating through soils made of relatively fresh and reactive organic matter (see e.g., Kaplan et al, 2011;Zhang et al, 2011).…”

Section: Discussionmentioning

confidence: 51%

How mobile is iodide in the Callovo–Oxfordian claystones under experimental conditions close to the in situ ones?

Savoye

Frasca

Grenut

et al. 2012

Journal of Contaminant Hydrology

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Section: Discussionmentioning

confidence: 51%

How mobile is iodide in the Callovo–Oxfordian claystones under experimental conditions close to the in situ ones?

Savoye

Frasca

Grenut

et al. 2012

Journal of Contaminant Hydrology

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“…Reduction of iodate by soil organic matter may precede conversion of inorganic iodine into organic forms (Whitehead, 1974b;Fukui et al, 1996). Steinberg et al (2008b) confirmed that iodate heated with peat and lignin over a pH range of 3.5-9 was converted to organic iodine forms and iodide; Francois (1987a) observed that the iodine content of humic substances increased following incubation with iodate for 5 days. In both cases it was shown that iodate was first reduced to reactive intermediate products, I 2 or HOI, which then reacted rapidly with the organic matter.…”

Section: Introductionmentioning

confidence: 79%

Iodine dynamics in soils

Shetaya

Young

Watts

et al. 2012

Geochimica et Cosmochimica Acta

135

118

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We investigated changes in iodine ( 129 I) solubility and speciation in nine soils with contrasting properties (pH, Fe/Mn oxides, organic carbon and iodine contents), incubated for nine months at 10 and 20°C. The rate of 129 I sorption was greater in soils with large organic carbon contents (%SOC), low pH and at higher temperatures. Loss of iodide (I À ) from solution was extremely rapid, apparently reaching completion over minutes-hours; iodate (IO À 3 ) loss from solution was slower, typically occurring over hours-days. In all soils an apparently instantaneous sorption reaction was followed by a slower sorption process for IO À 3 . For iodide a faster overall reaction meant that discrimination between the two processes was less clear. Instantaneous sorption of IO À 3 was greater in soils with high Fe/Mn oxide content, low pH and low SOC content, whereas the rate of time-dependent sorption was greatest in soils with higher SOC contents. Phosphate extraction (0.15 M KH 2 PO 4 ) of soils, $100 h after 129 I spike addition, indicated that concentrations of sorbed inorganic iodine ( 129 I) were very low in all soils suggesting that inorganic iodine adsorption onto oxide phases has little impact on the rate of iodine assimilation into humus. Transformation of dissolved inorganic 129 IO À 3 and 129 I À to sorbed organic forms was modelled using a range of reactionand diffusion-based approaches. Irreversible and reversible first order kinetic models, and a spherical diffusion model, adequately described the kinetics of both IO À 3 and I À loss from the soil solution but required inclusion of a distribution coefficient (k d ) to allow for instantaneous adsorption. A spherical diffusion model was also collectively parameterised for all the soils studied by using pH, soil organic carbon concentration and combined Fe + Mn oxide content as determinants of the model parameters (k d and D/r 2 ). The kinetic model parameters were not directly related to a single soil parameter; inclusion of pH, SOC, oxide content and temperature was necessary to describe the observed behaviour. From the temperature-dependence of the sorption data the activation energy (E a ) for 129 IO À 3 transformation to organic forms was estimated to be $43 kJ mol À1 . The E a value was independent of %SOC and was consistent with a reaction mechanism slower than pore diffusion or physical adsorption, but faster than most surface reactions.

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“…Iodine in the form of IO 3 À is more retarded and behaves very differently as indicated by elevated K d values (1-1000 mL/g) (Rechard, 1995;Kaplan et al, 2000;Schwehr et al, 2009;Kaplan et al, 2011). The reduction of IO 3 À to I À by SOM or partial conversion to organo-iodine was observed in recent studies (Steinberg et al, 2008;Yamaguchi et al, 2010;Zhang et al, 2010Zhang et al, , 2011. However, very few studies have tracked the chemical characteristics and mobility of naturally occurring organoradioiodine.…”

Section: Colloidal Organic Macromolecules As a Radioiodine Sourcementioning

confidence: 89%