Coastal monitoring: Seventeen more samples are in the books. Mostly from March and a few from April; no coastal samples contained any of the Fukushima fingerprint isotope, 134Cs (2 year half-life). Low levels of 137Cs (~30 year half-life) were present in all of the samples. These new data continue to lie along the increasing trend which indicates that the leading edge of the Fukushima plume is in BC’s coastal waters.
The above trend is clear and shows a steady rise that would predict that the average sample will have double the initial background concentrations of 137Cs sometime this summer. While still far below the 10,000 Bq m-3 level of concern for cesium radionuclides in drinking water, these more contaminated samples should also more regularly contain the Fukushima fingerprint isotope, 134Cs.
While the increasing 137Cs trend is clear for the whole coast, it is also evident that each region is telling the story of how ocean waters circulate in coastal British Columbia.
Looking at this regional graph and focusing on the period from August 2015 – March 2016, we see the highest concentrations of 137Cs shift from appearing on the west coast of Vancouver Island northward to Haida Gwaii. As explored last month, this could indicate a northward shift of the North Pacific Current bifurcation.
Summer sampling season is back! We’re coordinating with many of the same First Nations as in 2015 for repeat sampling of the same salmon populations. In addition to salmon, this year we are joined by Dr. Helen Gurney-Smith from Vancouver Island University who specializes in marine invertebrates. She is coordinating the collection of mussels, clams, oysters, and scallops from all of the major shellfish beds in BC waters including Baynes Sound, Quadra Island, and Haida Gwaii. These samples will be new species in our sampling repertoire and will help us see how sessile organisms take up Fukushima radionuclides along the coast. The resulting data will be valuable to invertebrate scientists like Dr. Gurney-Smith and reassure consumers of the the $33 million BC shellfish industry.
Three research cruises will collect InFORM samples this summer. Two out to Ocean Station Papa in the central NE Pacific, and currently, undergrad Saskia Kowallik is aboard the CCGS Sir Wilfred Laurier enroute from Sidney, BC to Dutch Harbor, then onto Barrow, AK. She will be reporting in a few times while away and you can read her first dispatch here.
Additionally, Dr. John Smith says that initial results from the February 2016 Line P cruise indicate that the concentrations of 134-Cs may have plateaued at Ocean Station Papa and possibly slightly decreasing. This isn’t so much a true decline as it is a smearing of the signal as the radionuclides are dispersing throughout the rest of the NE Pacific. In other interesting news, Dr. Smith just returned from a meeting in China where a colleague used a highly specialized gamma spectrometer and a very large volume of water sampled in the Chuckchi Sea to detect the trace level of 134-Cs that is ~5 times lower than the detection threshold (0.2 – 0.4 Bq m-3) for the instrumentation used at the University of Ottawa where the coastal samples are processed. This means that minute amounts of Fukushima contamination are entering the Arctic Ocean and that that it only takes ~5 years for waters to transit from coastal Japan to the Arctic. With the ability to detect such low levels of contamination, it will be interesting to see what else we can learn about oceanic transport times as monitoring continues into the future.
*Note: Results are preliminary and may be slightly adjusted pending results from further chemical analysis.