The recent study by the Nuclear Environment Safety and Tracing Team at the Institute of Earth Environment, Chinese Academy of Sciences, investigated the temporal variations of radioactive iodine-129 (129I) and its stable isotope flux in sediment cores from Ma'er Lake in Sihailong Bay. For the first time, they quantitatively reconstructed the high-resolution deposition history of atmospheric 129I in East Asia over the past 170 years. This research was published in Science of the Total Environment.
The study reveals a significant increase in both the concentration of 129I and the 129I/127I atomic ratio in lake sediment cores since the 1950s compared to the pre-nuclear era. It traced the sources and transport processes of 129I in the sediment cores of Sihailong Bay. Besides the radioactive fallout from global atmospheric nuclear weapons testing, atmospheric 129I emissions from nuclear fuel reprocessing plants are transported from Europe to East Asia by mid-latitude westerlies and are primarily preserved in sediments through dry and wet deposition. Additionally, the study found that the high organic matter content and strong reducing conditions in lake sediments effectively immobilize iodine, limiting its vertical migration within the sediment column. The estimated total amount of 129I during the study period (1846-2021) is 11.9×1012 atom/m2, with a human contribution of 97.1%, and post-nuclear era 129I accounting for 96.2% of the total amount. These findings provide a new perspective for assessing the impact of human nuclear activities on the environment in East Asia and studying the characteristics of the Anthropocene.
Link to the related paper: https://doi.org/10.1016/j.scitotenv.2024.172031
