Iodine isotopes (129I and 127I) in the hydrosphere of Qinghai-Tibet region and South China Sea

Publication date: December 2018
Source:Journal of Environmental Radioactivity, Volume 192
Author(s): Peng Yi, Xuegao Chen, Zixia Wang, Ala Aldahan, Xiaolin Hou, Zhongbo Yu
The radioactive isotope ¹²⁹I, with a half-life of 1.57 × 10⁷ years, is widely used as a tracer to assess nuclear safety, to track environmental and geological events and to figure out the details of the stable iodine geochemical cycle. This work investigated the ¹²⁹I and ¹²⁷I distribution in water samples collected from the terrestrial (rivers, lakes and springs) and marine water systems (estuary and sea) in China. The measured ¹²⁹I concentrations of (1–51) × 10⁶ atoms/L and ¹²⁹I/¹²⁷I ratios of (0.03–21) × 10⁻¹⁰ shows the variability of ¹²⁹I level in the water systems. The local permafrost and seasonal frozen environment play a key role in groundwater recharge in the Qinghai-Tibet region, which is reflected in the ¹²⁹I distribution in surface water. The depth distribution of ¹²⁹I in the water column of the South China Sea reflects the effluence of different currents. The results also indicate that the hydrosphere of China contains one to three orders of magnitude less ¹²⁹I compared to those reported in Europe. Despite the large distance, the European nuclear fuel reprocessing facilities represent the major source of ¹²⁹I in the hydrosphere of China through atmospheric transport. The contribution of the Fukushima nuclear accident to ¹²⁹I levels in the hydrosphere of China was negligible.



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