Location :Scientists Reconstruct a High-resolution Atmospheric Iodine-129 Deposition History over 170 Years in East Asia
A recent study published in Science of the total Environment successfully reconstructs the atmospheric deposition history of radioactive iodine-129 (129I) over the past 170 years, based on the analysis of a sediment core from the Sihailongwan Maar Lake, northeast China. This work provides a novel insight into the historical environmental impact of human nuclear activities in East Asia and the characteristics of the Anthropocene.
As one of major fission products, radioactive iodine-129 (129I) in the surface environment is dominantly from human nuclear activities since the nuclear era. It is not only a ideal tracer for nuclear enironmental safety, but also a useful tracer for envinronmental process (i.e., oceanic current circulation, air mass movement, geological dating). Despite abundant 129I records have been reported in natural archives, there are still few long-time series of 129I deposition flux and invetory.
To address the impact of human nuclear activities on East Asia, the research group of Nuclear Environmental Safety and Tracing from the Institute of Earth Environment of the Chinese Academy of Sciences (CAS), retrevied the temporal variation of the radioactive 129I and stable isotope 127I in Sihailongwan Maar Lake sediment, and reconstructed longest time-series of atmospheric deposition history of radioactive iodine-129 in East Asia so far. They found significant increases in 129I concentrations and the 129I/127I atomic ratios since the 1950s, indicating the significant impact from the global fallout of atmospheric nuclear weapons testing, spent fuel reprocessing in England, France and Russia. 129I was transported by the mid-latitude westerly and East Asian monsoon to northeast China.
“Since the Sihailongwan Maar Lake only receives atmospheric deposition, our reconstructed result of 129I fluxes utilizing the varve sediment is in good coincidence with a Japanese observation of atmospheric fallout in similar latitude areas, and proves reliable and accurate.” said Dr. ZHANG luyuan, the corresponding author. Based on their estimation, over the past 170 years, the natural and anthropogenic contributions were 2.86 % and 97.1 %, respectively, suggesting the overwhelming human contribution in the Anthropocene, far exceeding the natural contribution. The nuclear fuel reprocessing plants discharges from England and France have contributed 87.6% of the total 129I inventory. The reconstructed fluxes and inventory of atmospheric 129I deposition history distinguish the natural and artificial contributions, providing a novel perspective on the historical environmental impact of human nuclear activities in East Asia.
Contact: BAI Jie, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China. Email: baijie@ieecas.cn
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