Atmospheric gaseous and particulate Iodine-129 in Seville (Spain)
Dr. José María López-Gutiérrez1,2, Mr. Juan Ignacio Peruchena2,3, Dr Guillermo Manjón1
1Universidad de Sevilla, Sevilla, Spain, 2Centro Nacional de Aceleradores (Universidad de Sevilla, CSIC, Junta de Andalucía) , Sevilla, Spain, 3Consejo Superior de Investigaciones Científicas, Sevilla, Spain
The origin of atmospheric 129I in the Northern Hemisphere is, nowadays, clearly linked to the emissions of the nuclear fuel reprocessing plans (NFRP) of Sellafield and La Hague. It is well known that these plants have released high amounts of 129I in both liquid and gaseous forms. Most part of the liquid discharges travel from both plants to the North Sea and then to the Arctic along the Norwegian coast. However, the impact of 129I liquid discharges is already evident in the whole North Atlantic Ocean. On the other hand, gaseous discharges, although much lower than liquid ones, distribute quickly over the Northern Hemisphere.
In the last years, there has been a discussion on the origin of atmospheric 129I in Europe. Last studies carried out in Norther Europe seem to show that the formation of sea spray is the main responsible of the 129I in aerosols, as shown for example in Denmark . In this work, 129I/127I ratios agree well with the ones measured recently in the North Sea. This and other evidence show that the North Sea surface is responsible for the presence of 129I in Danish aerosols. This result is compatible with previous results obtained for Northern and Central Europe.
In this work, we present weekly results for the 129I concentrations and 129I/127I ratios measured in the air of Sevilla (Spain) during the year 2013. Both magnitudes were determined independently by Accelerator Mass Spectrometry on polypropylene filters in order to determine them on particulate iodine. Also, 129I concentrations were measured in charcoal filters, that give information on gaseous iodine. Results show that the presence of 129I in the gaseous form is much more important than the particulate form. Particulate 129I concentrations are typically in the order of 104 at/m3 while gaseous 129I concentrations are at least one order of magnitude higher. 129I/127I ratios in particulate iodine are in the order of 10-9-10-8, and they are being currently determined in gaseous iodine. The origin of this 129I is not so clear as in Northern Europe, Surface North Atlantic water at mid latitudes has been shown to present isotopic ratios of 10-10 to low 10-8 recently , slightly lower than the ones measured in our work. However, no clear correlation between western wind origin in Sevilla during the periods of high 129I concentration.
Apart from this, there seems to be a correlation between gaseous and particulate 129I, which could reveal a common origin at least in a fraction of it or changes of physical form on the way from the source to the city.
 Zhang, L., Hou, X., and Xu, S.: Speciation of 127I and 129I in atmospheric aerosols at Risø, Denmark: insight into sources of iodine isotopes and their species transformations, Atmos. Chem. Phys., 16, 1971–1985, https://doi.org/10.5194/acp-16-1971-2016, 2016.
 He P, Hou X, Aldahan A, Possnert G, Yi P. Iodine isotopes species fingerprinting environmental conditions in surface water along the northeastern Atlantic Ocean. Sci Rep. 2013 Nov 28;3:2685. doi: 10.1038/srep02685. PMID: 24284916; PMCID: PMC3842550.
This work is presented by José María López-Gutiérrez, associated professor at the University of Seville and member of the AMS group at CNA Sevilla. He has dedicated most part of his research career to the application of AMS to the detection of Iodine-129, trying to obtain information on its distribution in the environment and its relation to environmental problems.
The AMS group at CNA has participated in all the AMS conferences since Vienna in 1999. Their research includes both AMS technique and applications, especially those related to the study of long-lived artificial radionuclides in the environment as Iodine-129 and actinides.
Atmospheric gaseous and particulate 129I in Seville (Spain)
López-Gutiérrez, José María1,3, Peruchena, Juan Ignacio2,3
1 Dpto. Física Aplicada I, Escuela Politécnica Superior, Universidad de Sevilla (Spain)
2 Consejo Superior de Investigaciones Científicas (CSIC) (Spain)
3 Centro Nacional de Aceleradores (Universidad de Sevilla, CSIC, Junta de Andalucía) (Spain)