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Short-Term Iodine Dynamics in Soil Solution

Humphrey, Olivier S.; Young, Scott D.; Crout, Neil M.J.; Bailey, Elizabeth H.; Ander, E. Louise; Watts, Michael J.


Olivier S. Humphrey

Scott D. Young

Professor of Environmental Modelling

Associate Professor

Principal Research Fellow

Michael J. Watts


Assessing the reactions of iodine (I) in soil is critical to evaluate radioiodine exposure and understand soil-to-crop transfer rates. Our mechanistic understanding has been constrained by method limitations in assessing the dynamic interactions of iodine between soil solution and soil solid phase over short periods (hours). We use microdialysis to passively extract soil solution spiked with radioiodine (129I- and 129IO3-) to monitor short-term (≤40 h) in situ fixation and speciation changes. We observed greater instantaneous adsorption of 129IO3- compared to 129I- in all soils and the complete reduction of 129IO3- to 129I- within 5 h of addition. Loss of 129I from solution was extremely rapid; the average half-lives of 129I- and 129IO3- in soil solution were 4.06 and 10.03 h, respectively. We detected the presence of soluble organically bound iodine (org-129I) with a low molecular weight (MW) range (0.5-5 kDa) in all soils and a slower (20-40 h) time-dependent formation of larger MW org-I compounds (12-18 kDa) in some samples. This study highlights the very short window of immediate availability in which I from rainfall or irrigation remains in soil solution and available to crops, thus presenting significant challenges to phytofortification strategies in soil-based production systems.


Humphrey, O. S., Young, S. D., Crout, N. M., Bailey, E. H., Ander, E. L., & Watts, M. J. (2020). Short-Term Iodine Dynamics in Soil Solution. Environmental Science and Technology, 54(3), 1443-1450.

Journal Article Type Article
Acceptance Date Jan 10, 2020
Online Publication Date Jan 10, 2020
Publication Date Feb 4, 2020
Deposit Date Feb 3, 2020
Publicly Available Date Jan 11, 2021
Journal Environmental science & technology
Print ISSN 0013-936X
Electronic ISSN 1520-5851
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 54
Issue 3
Pages 1443-1450
Keywords General chemistry; Environmental chemistry
Public URL
Publisher URL
Additional Information This document is the Accepted Manuscript version of a Published Work that appeared in final form in Environmental Science and Technology, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see, see].


Humphrey Et Al 2020 Short-Term Iodine Dynamics In Soil Solution (1.1 Mb)

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