Advances on the determination of atmospheric ~(129)I by accelerator mass spectrometry (AMS)

摘要

~(129)I is a long-life (T_(1/2) = 15.7 x 10~6 years) radionuclide whose presence in the environment has increased strongly since the beginning of the nuclear age. Its great potential as a radioactive tracer has been shown in the literature. However, data in the different compartments are scarce, so its behaviour in the environment is still not well known. One of the reasons of this situation is that the only technique able to detect ~(129)I levels in zones not directly affected by artificial sources is accelerator mass spectrometry. In this work, following previous studies in atmospheric samples (rainwater and gaseous samples), we present results on the presence of ~(129)I in aerosols in Southern Spain. The isotopic ratio ~(129)I/~(127)I has been measured in aerosol filters from high volume samplers with a monthly resolution during years 2001 and 2002. Results show marked variations in short time scales. No short term correlation with the gaseous ~(129)I discharges of the two main nuclear fuel reprocessing plants (Sellafield and La Hague) can be deduced. However, a quite clear relationship between these emissions and the ~(129)I levels in this and other types of atmospheric samples previously studied at longer time scales can be demonstrated.