The atmospheric transport of iodine‐129 from Fukushima to British Columbia, Canada and its deposition and transport into groundwater

Abstract

The Fukushima-Daiichi nuclear accident (FDNA) released iodine-129 (15.7 million year half-life)and other fission product radionuclides into the environment in the spring and summer of 2011. 129 I is recognized as a useful tracer for the short-lived radiohazard 131 I, which has a mobile geochemical behavior with potential to contaminate water resources. To trace 129 I released by the FDNA reaching Canada, preaccident and post-accident rain samples collected in Vancouver, on Saturna Island and from the National Atmospheric Deposition Program in Washington State were measured. Groundwater from the AbbotsfordSumas Aquifer was sampled to determine the fate of 129 I that infiltrates below the root zone. Modeling of vadose zone transport was performed to constrain the travel time and retardation of 129 I. The mean preaccident 129 I concentration in rain was 31 3 10 6 atoms/L (n 5 4). Immediately following the FDNA, 129 I values increased to 211 3 10 6 atoms/L and quickly returned to near-background levels. However, pulses of elevated 129 I continued for several months. The increases in 129 I concentrations from both Vancouver and Saturna Island were synchronized, and occurred directly after the initial release from the FDNA. The 129 I in shallow ( 3 H/ 3 He age <1.4 years) Wassenaar et al. (2006) groundwater showed measurable variability through March 2013 with an average of 3.2 3 10 6 atoms/L (n 5 32) that was coincident with modeled travel times for Fukushima 129 I. The groundwater response and the modeling results suggest that 129 I was partially attenuated in soil, which is consistent with its geochemical behavior; however, we conclude that the measured variability may be due to Fukushima 129 I entering groundwater.

High-frequency NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; isotope (&lt;i&gt;δ&lt;/i&gt;&lt;sup&gt;15&lt;/sup&gt;N, &lt;i&gt;δ&lt;/i&gt;&lt;sup&gt;18&lt;/sup&gt;O) patterns in groundwater recharge reveal that short-term changes in land use and precipitation influence nitrate contamination trends

“…Approximately 76 % of the shallow groundwater locations (16 of 19 sites) exceeded the maximum allowable concentration (MAC) of 10 mg N L −1 in the Canadian Drinking Water Guidelines (Health Canada, 2013). These nitrate exceedances were consistent with previous observations of high nitrate concentrations in shallow wells in the aquifer (Hii et al, 1999). Previous studies reported NO − 3 concentrations exceeding the MAC in 58 %, 69 %, and 59 % of wells (Wassenaar, 1995;Zebarth et al, 1998;Wassenaar et al, 2006), respectively.…”

Iodine: An Essential Trace Element

“…Iodine-129 is a major environmental pollutant [11]. Its continued use since 1940 has caused a dangerous increase of this isotope in the environment, with a greater accumulation in surface and groundwater [12,13].…”

Insight Into Radio‐Isotope 129I Deposition in Fresh Snow at a Remote Glacier Basin of Northeast Tibetan Plateau, China

“…I distribution and dispersion in the troposphere • The source of the deposited 129 I in glacier snowpack is located in the upper troposphere • A hypothetic model on the transport, dispersion, and removal of 129 I in the troposphere is provided particulates during transport, which have large residence time and can be dispersed over large distances Keogh et al, 2009;Masson et al, 2011;Reithmeier et al, 2006). However, 129 I released into the lower troposphere has a much smaller residence time of about two weeks, as demonstrated by the increased concentrations of 129 I found in the Northeast British Columbia of Canada (Herod et al, 2015). However, 129 I released into the lower troposphere has a much smaller residence time of about two weeks, as demonstrated by the increased concentrations of 129 I found in the Northeast British Columbia of Canada (Herod et al, 2015).…”

“…In the case of the Fukushima accident, since violent explosions occurred at very high temperatures (more than 1400°C), radioisotopes were first expelled and dispersed to the atmosphere. However, 129 I released into the lower troposphere has a much smaller residence time of about two weeks, as demonstrated by the increased concentrations of 129 I found in the Northeast British Columbia of Canada (Herod et al, 2015). For the radioisotope fraction injected into the stratosphere the transit time back to the troposphere is of the order of years and the transport at this high altitude contributes to the 129 I dispersion over the globe (Blinov et al, 2000), and probably to the remote alpine glaciers in the Tibetan Plateau, as the data presented later in this study show.…”