Speaker
Description
129I (T1/2 = 15.7 × 106 y) is a radionuclide whose presence in the environment changed strongly due to the emissions from the two largest nuclear fuel reprocessing plants in Europe: Sellafield (UK) and La Hague (France). Most of the 129I has been discharged to the sea, but part of it is released as gaseous 129I. Liquid discharges of 129I mostly travelled from these plants to the North Sea and then to the Arctic along the Norwegian coast. The geochemical cycle of iodine includes continue interchanges between different environmental compartments, including the atmosphere, where it can travel long distances despite its short residence time. 129I can be a tracer of atmospheric processes. Besides, it can be an indicator of the presence of shorter-lived iodine isotopes released in nuclear accidents. However, there are not many recent data on the presence of 129I in the atmosphere.
In this work we present the results for atmospheric 129I/127I isotopic ratios over four cities in Spain: Bilbao (43°15′N), Seville (37°23′N), Malaga (36°43′N) and La Laguna (28°29′N) during the first three months of 2023. The evolution of the isotopic ratios was very similar in the four cases, revealing a common origin of 129I. The results showed 129I/127I isotopic ratios in the order of 10-10 to 10-8 for the four cities but showing a clear dependence on latitude. Highest ratios were measured in Bilbao, the most septentrional city, while the lowest ones were found on La Laguna, placed in the Canary Island. In average, 129I/127I ratios were a factor of 4.5 higher in Bilbao than in La Laguna during this period. Finally, it could also be observed that the values found in Sevilla were in the same range than the ones measured in 2013, previously to the closing of the Sellafield reprocessing plant.
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