Monitoring rainwater and seaweed reveals the presence of 131I in southwest and central British Columbia, Canada following the Fukushima nuclear accident in Japan

Abstract

Detailed analysis of 131 I levels in rainwater and in three species of seaweed (Fucus distichus Linnaeus, Macrocystis pyrifera, and Pyropia fallax) collected in southwest British Columbia and Bella Bella, B.C., Canada was performed using gamma-ray spectroscopy following the Germanium Detector for Elemental Analysis and Radioactivity Studies (GEARS) was modeled using the Geant4 software package and developed as an analytical tool by the Nuclear Science group in the Simon Fraser University Department of Chemistry for the purpose of these measurements.

Fukushima Daiichi–Derived Radionuclides in the Ocean: Transport, Fate, and Impacts

“…For example, 131 I was detected in Fucus seaweed in Vancouver, Canada, at a maximum activity of 4,930 Bq kg −1 following the CNPP accident; shortly after the FDNPP releases, seaweed from the same general area had activities of 130 Bq kg −1 (Chester et al 2013). Pacific bluefin tuna (Thunnus orientalis) caught off San Diego in August 2011 had detectable 134 Cs and 137 Cs activities of 4 and 6 Bq kg −1 ww, respectively (Madigan et al 2012), whereas albacore (Thunnus alalunga) caught off the US Pacific Northwest coast in 2012 had even lower 134 Cs and 137 Cs activities (0.02-0.4 and 0.2-0.8 Bq kg −1 ww, respectively) (Neville et al 2014).…”

Fukushima-derived radioactivity measurements in Pacific salmon and soil samples collected in British Columbia, Canada

“…This detector has proven useful in the past to monitor 131 I levels in environmental samples in the months immediately following the nuclear accident 2 and more recently in a similar project to measure radiocesium in sockeye salmon collected from First Nations fisheries on Vancouver Island. 15 A more detailed description of the detector setup for the environmental monitoring campaigns may be read in Chester et al 2 The absolute efficiency of GEARS while measuring point sources was evaluated using the technique described in Rizwan et al 22 Homogenised environmental samples were measured for 2-10 days in a glass vial, a 300 mL Marinelli beaker, or a 600 mL Marinelli beaker depending on their size. The absolute efficiency of GEARS while measuring environmental samples in these extended volumes was determined using the GEANT4 software package 23,24 via the method described in Chester et al 2 …”

“…In the years after the FNA, there have been significant efforts by the international community to measure the radionuclides from Fukushima, which were released into the atmosphere [2][3][4][5][6] or directly into the Pacific Ocean. 1,[7][8][9] As cesium has been previously shown to accumulate in tissues, additional monitoring campaigns have been initiated to investigate the contamination of various freshwater 5,6 and marine 7,[10][11][12][13][14][15] biota, as well as to develop 137 Cs bioaccumulation models in Pacific food-webs.…”

A method for establishing absolute full-energy peak efficiency and its confidence interval for HPGe detectors

“…This paper reports the efficiency calibration procedure developed for the germanium detector for elemental analysis and radioactivity studies (GEARS) detector in the Department of Chemistry, Simon Fraser University [1], used for environmental radioactivity measurements and neutron-activation analysis. In both types of studies, the accuracy and precision of the absolute efficiency calibration of the high purity germanium (HPGe) detector defines the accuracy and precision of the measurement performed.…”

“…Section 5 presents a comparison to the previous measurements, reported in Ref. [1], in a smaller energy range and Monte Carlo calculations of the absolute efficiency performed using the GEANT4 framework [5]. Section 6 summarizes the main advantages of the method.…”