Bioreduction of iodate in sediment microcosms

Iodine-129 is a high-yield fission product formed in nuclear reactors and is a risk-driving radionuclide in both contaminated land and radioactive waste disposal due to its high mobility and long half-life. Here, the bioreduction behaviour of iodate was investigated by tracking iodine speciation and...

Full description

Saved in:
Bibliographic Details
Published in:Mineralogical magazine 2015-11, Vol.79 (6), p.1343-1351
Main Authors: Guido-Garcia, Fabiola, Law, Gareth T. W, Lloyd, Jonathan R, Lythgoe, Paul, Morris, Katherine
Format: Article
Language:English
Subjects:
bacteria
biogenic processes
bioreduction
chemical fractionation
Environmental geology
experimental studies
ferric iron
Geochemistry
halides
halogens
high-level waste
I-129
iodate
iodates
iodide
iodides
iodine
iron
isotopes
manganese
metals
microorganisms
radioactive iodine
radioactive isotopes
radioactive waste
reduction
sediments
solutions
speciation
valency
waste disposal
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Iodine-129 is a high-yield fission product formed in nuclear reactors and is a risk-driving radionuclide in both contaminated land and radioactive waste disposal due to its high mobility and long half-life. Here, the bioreduction behaviour of iodate was investigated by tracking iodine speciation and concentration in solution during the development of progressive anoxia in sediment microcosm experiments incubated at neutral pH. Experiments with acetate added as an electron donor showed the expected cascade of terminal electron-accepting processes. Analysis of solution chemistry showed reduction of iodate to iodide during the early stages of metal (Mn(IV) and Fe(III)) reduction, but with no significant retention of iodine species on solids. There was, however, a net release of natural iodine associated with the sediments to solution when robust iron reduction/sulfate reduction had developed. In addition, over 210 days, the controls with no electron donor and the sterile controls showed no Mn(IV) or Fe(III) reduction but displayed modest sorption of iodate to the sediments in the absence of bioreduction. Overall these results show that under oxic conditions iodate may be partially sorbed to sediments over extended periods but that development of mildly reducing conditions leads to the reductive release of iodine to solution as iodide.
ISSN:0026-461X
1471-8022
DOI:10.1180/minmag.2015.079.6.10