Partition of iodine ((129)I and (127)I) isotopes in soils and marine sediments
2011 (English)In: Journal of Environmental Radioactivity, ISSN 0265-931X, E-ISSN 1879-1700, Vol. 102, no 12, 1096-1104 p.Article in journal (Refereed) Published
Natural organic matter, such as humic and fulvic acids and humin, plays a key role in determining the fate and mobility of radioiodine in soil and sediments. The radioisotope (129)I is continuously produced and released from nuclear fuel reprocessing plants, and as a biophilic element, its environmental mobility is strongly linked to organic matter. Due to its long half-life (15.7 million years), (129)I builds up in the environment and can be traced since the beginning of the nuclear era in reservoirs such as soils and marine sediments. Nevertheless, partition of the isotope between the different types of organic matter in soil and sediment is rarely explored. Here we present a sequential extraction of (129)I and (127)I chemical forms encountered in a Danish soil, a soil reference material (IAEA-375), an anoxic marine sediment from Southern Norway and an oxic sediment from the Barents Sea. The different forms of iodine are related to water soluble, exchangeable, carbonates, oxides as well as iodine bound to humic acid, fulvic acid and to humin and minerals. This is the first study to identify (129)I in humic and fulvic acid and humin. The results show that 30-56% of the total (127)I and 42-60% of the total (129)I are associated with organic matter in soil and sediment samples. At a soil/sediment pH below 5.0-5.5, (127)I and (129)I in the organic fraction associate primarily with the humic acid while at soil/sediment pH > 6 (129)I was mostly found to be bound to fulvic acid. Anoxic conditions seem to increase the mobility and availability of iodine compared to oxic, while subaerial conditions (soils) reduces the availability of water soluble fraction compared to subaqueous (marine) conditions.
Place, publisher, year, edition, pages
2011. Vol. 102, no 12, 1096-1104 p.
Iodine-129, 127, Speciation, Iodine humic substances, ICP-MS, AMS
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:uu:diva-161912DOI: 10.1016/j.jenvrad.2011.07.005ISI: 000296483500005OAI: oai:DiVA.org:uu-161912DiVA: diva2:458850