This post is based on a summary provided by Dr. Jonathan Kellogg at the InFORM website. This post continues a series dedicated to provide the most sound, scientifically derived information on the impact of the Fukushima Daiichi nuclear disaster on the health of the environment and the public.
The Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project has now processed and released results from over 250 seawater samples collected by our citizen science volunteers from up down the British Columbia coast. The most recent results are from April and May 2016. Gamma spectrometry analyses on these samples failed to detect 134Cs (2 year half-life) which because of its relatively short half-life serves as a fingerprint of Fukushima contamination. The project continues to detect low levels of 137Cs (~30 year half-life) in seawater along the coast. Levels of 137Cs continue to increase with time at the shoreline which suggests that although we have no unequivocal signature of Fukushima contamination the leading edge of the contaminated water from the disaster is now arriving at the coast. Regional differences in the amount of 137Cs likely reflect and provide information on surface ocean currents in our region.
The steady rise allows us to forecast that, by this summer, the average sample will have double the initial background contamination of 137Cs present due to atmospheric weapons testing and the Chernobyl disaster back in the 20th century. These levels will still be far below the 10,000 Bq m-3 level of concern for cesium radionuclides in drinking water.
While 137Cs levels are increasing up and down the coast, it is also evident that regional differences provide some information on how ocean waters circulate in coastal British Columbia.
Analysis with data grouped into regions as follows: Haida Gwaii / North Coast: Lax Kw’alaams, Prince Rupert, Masset, Hartley Bay, Sandspit, North Van Is / Central Coast: Bella Bella, Port Hardy, Winter Harbour, West Coast Van Is: Tofino, Ucluelet, Bamfield, Strait of Georgia: Powell River, Vancouver, Salt Spring Island, South Van Is: Port Renfrew, Victoria.A first order interpretation of the regional graph would be that an event occurred during February and March 2016 that introduced less contaminated waters to the western and southern Vancouver Island stations. A tentative hypothesis may be that the North Pacific Bifurcation may have shifted. The coastal ocean is a dynamic place, as seen in this animation of satellite surface current observations and determining the exact cause of the changes in contamination over time is complicated.
Our project will continue to make observations of seawater and marine biota contamination from Fukushima in Canadian waters and provide radiological health risk assessments for those that rely on the ocean for their livelihood and/or recreation.