Here’s what we’ve been up to since we last touched base:
Coastal monitoring: While monthly samples continue to roll in from our diligent network of InFORMal scientists along the BC coast, analysis has been slowed by the intricate calibration process of our new gamma spectrometer at the University of Ottawa. This process was recently completed (read about it below), and we are excited to release new data!
Above are the results from samples collected in August 2015. Results from an additional 20 samples are also available from April, May, June, and July through the interactive map. New results should be available monthly, once again, now that the spectrometer is fully calibrated.
In summary, two of the analyzed samples tested positive for low levels of 134Cs, the isotope with a ~2 year half-life that is a fingerprint of Fukushima contamination, over the April-August period. Winter Harbour was the source of both samples, in April, and again in August. Our team in Winter Harbour actually collected two samples in the month of August, but the second sample is still in process (shown as white). Both samples have a total activity (134Cs + 137Cs) < 3 Bq m-3, which is lower than the May sample from Ucluelet (4 Bq m-3). Given that we know the plume of Fukushima contamination lies just offshore, the intermittant detection of these waters in the nearshore continues to highlight the complex currents and water movement that is typical of the coastal environment.
All samples continue to have measureable levels of 137Cs (half-life ~30 years), that is present due to atmospheric nuclear weapons testing that occurred in the 1950s and 1960s and the 1986 Chernobyl nuclear disaster.
A processing note: priority was given to more recent samples. As such, some samples from the April – August period remain to be analyzed. All prior samples will be analyzed as time on the detector permits.
Oceanic monitoring: Over 500 samples were collected on three summer research cruises across the NE Pacific. Initial findings report that values at Ocean Station Papa, at 50 N, 145 W (~1500 km off the BC coast), indicate that the total activity (134Cs + 137Cs) of cesium radionuclides continues to increase, though still <10 Bq m-3. Levels as high as 11.4 Bq m-3 were found during a June Our Radioactive Ocean research cruise along 150 W between Hawaii and Alaska. These values are ~3-4 Bq m-3 higher than observations from 2014 that were collected just to the east.This increasing trend indicates that the heart of the contaminated plume of seawater has yet to arrive in the NE Pacific. Also, these concentrations are proving to be slightly higher than numerical model predictions. Understanding these prediction/observation differences will advance our understanding of upper-ocean dynamics.
Biotic monitoring: Nearly 160 fish were collected over the summer from all major salmon runs returning to BC rivers. These fish were prepared for analysis at the Pacific Biological Station in Nanaimo, BC and are currently undergoing analysis at Health Canada’s Radiation Protection Bureau in Ottawa. Results from these analyses are expected early in the new year. Results from 24 Alaskan fish collected in 2015 found no detectable contamination so it will be interesting to compare our results.