Data from July and August samples keep creeping up the steady trend of increasing 137Cs concentations which indicates the Fukushima plume is in BC coastal waters. Interestingly, while the overall trend is for increasing 137Cs concentrations along the coast, the past few samples from Vancouver have measured near the lowest concentrations of our entire record. These low concentrations may be a temporary blip in an otherwise slight increasing trend, but time will tell that tale. Read the full December Update explaining this dip ->
More results from InFORM’s 2016 biotic monitoring results are now available and reveal that Fukushima contamination was not detected in sampled BC salmon after initial testing. These results are an update to the earlier report on the first 20 of the 123 fish donated by First Nations from 10 rivers in British Columbia and Yukon in 2016. Nine fish did have individual levels of 137Cs detected near the minimum detectable concentration (MDC). These levels (<0.7 Bq kg-1) are not known to present a significant health risk and are ~1,400x lower than the national and international action level (1000 Bq kg-1). For perspective, you would need to consume 1000-1500 kg of salmon at this concentration of cesium to receive the same radiation dose acquired during a single cross country flight. There has not been a significant increase to the total 137Cs concentration in BC salmon since InFORM monitoring began in 2014. Read the full 2016 update ->
The suite of summer 2015 oceanic data are now ready and they show quite a change from 2014. Comparing these data side by side, it is plain to see that the concentrations of 137Cs have increased considerably in the central NE Pacific. It appears that the plume has spread throughout this vast area from Alaska to California. While natural processes of radioactive decay are slowly decreasing concentrations of 134Cs (with a 2 year half-life roughly 25% of the original concentration was present in April 2015), the signal for 137Cs is getting smeared by the currents of the NE Pacific and as they paint the path of the highest flows.
It is good to point out that these data, courtesy of our partners at Our Radioactive Ocean and Fisheries and Oceans Canada, do not yet indicate a back side of the plume where the concentrations are beginnning to decrease. While this could mean that concentrations will continue to increase, numerical model simulations suggest that the smearing effect will continue to disperse the plume and that we are approaching the maximum. Data from samples collected this summer will show if that hypothesis is correct.
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