Journal ArticleDOI
Concentration-dependent mobility, retardation, and speciation of iodine in surface sediment from the Savannah River Site.
Saijin Zhang,Jinzhou Du,Chen Xu,Kathleen A. Schwehr,Yi-Fang Ho,Hsiu-Ping Li,Kimberly A. Roberts,Daniel I. Kaplan,Robin Brinkmeyer,Chris M. Yeager,Hyun-Shik Chang,Peter H. Santschi +11 more
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TLDR
Results demonstrate that the mobility of iodine species greatly depends on, in addition to the type of species, the iodine concentration used, presumably limited by the number of surface organic carbon binding sites to form covalent bonds.Abstract:
Iodine occurs in multiple oxidation states in aquatic systems in the form of organic and inorganic species. This feature leads to complex biogeochemical cycling of stable iodine and its long-lived isotope, (129)I. In this study, we investigated the sorption, transport, and interconversion of iodine species by comparing their mobility in groundwaters at ambient concentrations of iodine species (10(-8) to 10(-7) M) to those at artificially elevated concentrations (78.7 μM), which often are used in laboratory analyses. Results demonstrate that the mobility of iodine species greatly depends on, in addition to the type of species, the iodine concentration used, presumably limited by the number of surface organic carbon binding sites to form covalent bonds. At ambient concentrations, iodide and iodate were significantly retarded (K(d) values as high as 49 mL g(-1)), whereas at concentrations of 78.7 μM, iodide traveled along with the water without retardation. Appreciable amounts of iodide during transport were retained in soils due to iodination of organic carbon, specifically retained by aromatic carbon. At high input concentration of iodate (78.7 μM), iodate was found to be reduced to iodide and subsequently followed the transport behavior of iodide. These experiments underscore the importance of studying iodine geochemistry at ambient concentrations and demonstrate the dynamic nature of their speciation during transport conditions.read more
Citations
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Journal ArticleDOI
Radioiodine Biogeochemistry and Prevalence in Groundwater
Daniel I. Kaplan,Miles E. Denham,Saijin Zhang,Chris M. Yeager,Chen Xu,Kathy A. Schwehr,Hsiu-Ping Li,Yi-Fang Ho,Dawn M. Wellman,Peter H. Santschi +9 more
TL;DR: Advances have been made in detecting iodine species at ambient groundwater concentrations, defining the nature of the organic matter and iodine bond, and quantifying the role of naturally occurring sediment microbes to promote iodine oxidation and reduction, which have led to a more mechanistic understanding of radioiodine biogeochemistry.
Journal ArticleDOI
Iodine-129 and Iodine-127 speciation in groundwater at the Hanford Site, U.S.: iodate incorporation into calcite
Saijin Zhang,Chen Xu,Danielle Creeley,Yi-Fang Ho,Hsiu-Ping Li,Russell Grandbois,Kathleen A. Schwehr,Daniel I. Kaplan,Chris M. Yeager,Dawn M. Wellman,Peter H. Santschi +10 more
TL;DR: The common sampling artifact resulting in the precipitation of calcite by degassing CO2, had the unintended consequence of providing insight into a potential solution for the in situ remediation of groundwater (129)I.
Journal ArticleDOI
Sequestration and remobilization of radioiodine (129I) by soil organic matter and possible consequences of the remedial action at Savannah River Site.
Chen Xu,Eric J. Miller,Saijin Zhang,Hsiu-Ping Li,Yi-Fang Ho,Kathleen A. Schwehr,Daniel I. Kaplan,Shigeyoshi Otosaka,Kimberly A. Roberts,Robin Brinkmeyer,Chris M. Yeager,Peter H. Santschi +11 more
TL;DR: Results showed that 72-77% of the newly introduced I(-) or IO(3)(-) were irreversibly sequestered into the organic-rich riparian soil, while the rest was transformed by the soil into colloidal and truly dissolved organo-iodine, resulting in (129)I remobilization from the soil greatly exceeding the 1 pCi/L drinking water permit.
Journal ArticleDOI
Is soil natural organic matter a sink or source for mobile radioiodine (129I) at the Savannah River Site
Chen Xu,Saijin Zhang,Yi-Fang Ho,Eric J. Miller,Kimberly A. Roberts,Hsiu-Ping Li,Kathleen A. Schwehr,Shigeyoshi Otosaka,Daniel I. Kaplan,Robin Brinkmeyer,Chris M. Yeager,Peter H. Santschi +11 more
TL;DR: In this article, the authors measured stable 127 I and radioactive 129 I in humic acids (HAs) and fulvic acids (FAs) obtained by five successive alkaline, two glycerol and one citric acid-alkaline extraction, demonstrated that these extractable humic substances (HS) together account for 54-56% and 46% of the total 127 I in the soil, respectively.
Journal ArticleDOI
Molecular environment of stable iodine and radioiodine (129I) in natural organic matter: Evidence inferred from NMR and binding experiments at environmentally relevant concentrations
Chen Xu,Junyan Zhong,Patrick G. Hatcher,Saijin Zhang,Hsiu-Ping Li,Yi-Fang Ho,Kathleen A. Schwehr,Daniel I. Kaplan,Kimberly A. Roberts,Robin Brinkmeyer,Chris M. Yeager,Peter H. Santschi +11 more
TL;DR: In this paper, the molecular environment of stable iodine and radioiodine binding to soil organic matter (SOM) was analyzed using 13 C DPMAS NMR and solution state 1 H NMR on the eight humic acid fractions.
References
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TL;DR: Model V describes the binding of ions by humic substances in terms of complexation at discrete sites, modified by electrostatic attraction and/or repulsion, and also takes account of nonspecific binding due to counterion accumulation.
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Chemical contaminants on DOE lands and selection of contaminant mixtures for subsurface science research
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TL;DR: This article identified individual contaminants and contaminant mixtures that have been measured in the ground at 91 waste sites at 18 US Department of Energy (DOE) facilities within the weapons complex.
Journal ArticleDOI
Iodide accumulation provides kelp with an inorganic antioxidant impacting atmospheric chemistry.
Frithjof C. Küpper,Lucy J. Carpenter,Gordon McFiggans,Carl J. Palmer,Tim J. Waite,Eva-Maria Boneberg,Sonja Woitsch,Markus Weiller,Rafael Abela,Daniel Grolimund,Philippe Potin,Alison Butler,George W. Luther,Peter M. H. Kroneck,Wolfram Meyer-Klaucke,Martin C. Feiters +15 more
TL;DR: Using x-ray absorption spectroscopy, it is shown that the accumulated form is iodide, which readily scavenges a variety of reactive oxygen species (ROS) and is the first to be described in a living system.
Journal ArticleDOI
A review on speciation of iodine-129 in the environmental and biological samples
TL;DR: An overview of applications of (129)I speciation in various scientific disciplines such as radiation protection, waste depository, and environmental sciences is given and measurement techniques for the determination of ( 129)I are presented and compared.
Journal ArticleDOI
Update on intrathyroidal iodine metabolism.
John T. Dunn,Ann D. Dunn +1 more
TL;DR: Despite general agreement on the major steps in intrathyroidal iodine metabolism, new details of mechanisms are constantly being uncovered and are greatly improving understanding of the overall process.