Estimating the impact from Fukushima in Southern Spain by 131I and Accelerator Mass Spectrometry detection of 129I

After the Fukushima accident, large amounts of radionuclides were discharged to the atmosphere. Some of them travelled long distances and were detected in places as far from Japan as Spain a few days after the accident. One of these radionuclides was ¹³¹I. Its isotope ¹²⁹I (T1/2 = 15.7 × 106 years) was also expected to follow the same pathway. In this work, we present the results for the ¹²⁹I concentration in the same atmospheric samples from Seville (Spain) where ¹³¹I activity was measured in 2011 by Baeza et al. (2012). ¹²⁹I concentrations in aerosol and gaseous samples showed concentrations in the order of 104 and 105 atoms/m³, typically higher in the gaseous form with respect to the aerosol form. Also ¹²⁹I in rainwater was measured, showing concentrations in the order of 10⁸ atoms/L. The results show a very good agreement with the ¹³¹I profile, showing that, if background from other sources is not relevant, it is possible to estimate the impact of similar events years after them thanks to the sensitivity of techniques like Accelerator Mass Spectrometry.