Last evening I spoke at the monthly meeting of Surfrider Vancouver Island, one of InFORM’s non-governmental organization partners, to provide them with an update on our most recent results and progress. Surfrider VI helps to coordinate our citizen science volunteers who sample coastal seawater every month to monitor for Fukushima derived contamination along our beaches from Victoria in the south to Lax Kw’alaams in the north of BC. Surfrider VI is primarily responsible for sampling in Port Renfrew BC which is on the southwest coast of Vancouver Island.
I was pleasantly surprised by Lynn Wharram (Volunteer Coordinator and Combing the Coast BCU team lead) who had produced a short video chronicling her family collecting InFORM’s August 2016 seawater sample from the dock near the Port Renfrew Hotel. You can watch the video below.
You can read more about our citizen science program methods here, our NGO partners here , and our citizen science volunteers here. Thanks again to our volunteers and to Surfrider VI for all the work they do. Go and check them out if you are interested in ocean health (and surfing).
Our newest citizen scientist is 11-year-old Cameron Letnes who has been working alongside Cheryl Paavola of Northwest Community College in Prince Rupert British Columbia.
Cameron has been working on a number of science projects this summer. Not, only has she been working to collect seawater samples for Fukushima InFORM but she was also surveying for the invasive European Green Crab which is playing havoc with our native crab species along the BC coast. She says her favourite part of all of this work is learning how to use the various pieces of scientific equipment, especially the salinity refractometer.
The InFORM project can’t thank our citizen science volunteers enough for their hard work and dedication. Without their efforts our coastal seawater monitoring program would not be possible.
The purpose of this post is to report the most recent and last results from Kelp Watch 2015, a program dedicated to monitoring for Fukushima derived contamination along the Pacific Coast of North America. This post is the latest in a series dedicated to public outreach and dissemination of scientifically derived information about the impacts of the Fukushima Dai-ichi disaster on the health of the North Pacific Ocean ecosystem and health of North American residents. Results from the fifth sampling period (March 2 through June 3 2016) were released on July 15, 2016 and can be found here. As with previously reported results here, here, here, here, and here no radioactive isotopes from Fukushima were detected in kelp growing at sampling sites along our Pacific coast or elsewhere in the Pacific (see sampling sites). The absence of 134Cs in kelp suggests that ocean transport of Fukushima contamination had yet to reach persistently high enough levels in North American coastal water to bioaccumulate in kelp. The levels of Fukushima derived contamination in kelp in 2016 will not pose a significant risk to the health of the kelp or other species, including humans, which rely on them as a foodstuff.
The purpose of this post is to present measurements of artificial radionuclides in wild Atlantic salmon (Salmo salar) made in 1990’s and reported in a peer reviewed paper published in the Canadian Journal of Fisheries and Aquatic Sciences by Tucker and colleagues in 1999. This post is part of an ongoing series dedicated to communicating the results of scientific research aimed at The paper combines an understanding of bioconcentration of the artificial radionuclide 137-cesium (137Cs half life ~30 years) in marine food webs with quality measurements of the contaminant in salmon that spent their lives in the North Atlantic Ocean. The North Atlantic at the time had a strong east to west gradient in 137Cs concentrations in seawater with >10 Bq m-3 in the east owing to spent nuclear fuel reprocessing in Europe and the recent impact of the Chernobyl disaster and <1.5 Bq m-3 in the west near to Canada. Salmon returning to the Ste. Marguerite River in Canada had a wide range of radiocesium in their bodies which reflected the entire range of values seen in fish harvested across the Atlantic Ocean. The results indicate that the migration routes of these salmon extended all the way across the Atlantic to the Irish and Norwegian seas. The study is relevant to understanding the impact of the Fukushima disaster on radiocesium levels in Pacific salmon as the maximum levels of contamination of seawater we see in the central and eastern North Pacific is lower than the maximum levels studies by Tucker and colleagues. Given this fact we would predict that levels of Fukushima derived contaminants in Pacific salmon and the health risk associated with the consumption of these fish will be correspondingly lower. Thus far the salmon monitoring results from the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project are in keeping with the scientific communities understanding of 137Cs bioconcentration in fish outlined in the Tucker study and references therein.
Radionuclides in Atlantic Salmon: Bioconcentration and migration routes
When I was an undergraduate student at McGill University in Montreal, Dr. Joe Rasmussen (he is now at the University of Lethbridge in Alberta) headed up a freshwater ecology group that used radionuclides to understand energy and contaminant cycling in the aquatic environment. I remember learning about gamma spectrometry and the processing of samples for radionuclide determinations through conversations with his graduate students. Their work made an impression on me and highlighted the utility of radioisotopes for understanding rates of processes and pathways of contaminant transport in natural waters. The paper I will summarize here roughly dates to my time at McGill and is the work of Strahan Tucker who along with Marc Trudel works for Fisheries and Oceans Canada at the Pacific Biological Station in Nanaimo BC and part of the team of scientists working on the InFORM project. Tucker and colleagues exploited the east to west gradient in 137Cs activity in seawater in the North Atlantic to determine how much radiocesium was present in Atlantic salmon returning to the Ste. Marguerite River in Canada and by extension where they had migrated and fed during their growth and development. The figure below shows the high levels of seawater 137Cs contamination in the Irish Sea and eastern Atlantic compared to the western Atlantic near Canada owing to release of the isotope from fuel reprocessing plants in the UK and France and deposit of Chernobyl derived contamination in 1986.
137Cs distribution (Bq m–3) in waters of the North Atlantic with levels >10 in marginal seas of the eastern Atlantic and 0-1.5 in waters of the west near to Canada.
Given that salmon tend to bioconcentrate radiocesium about 130 times relative to the seawater in which the live (through the prey they consume) the predicted range in 137Cs in salmon from the eastern Atlantic would be 1.3 — 4.0 Bq kg-1 while fish living in the less contaminated western Atlantic would have 0.15 — 0.65 Bq kg-1. The range of 137Cs measured by Tucker and colleagues in salmon returning to the St. Marguerite River in Quebec, Canada, predicted ranges given seawater activities in the figure above and activities in fish harvested from different areas of the North Atlantic are summarized in the figure below.
Frequency distribution of 137Cs concentrations (Bq kg–1) in Atlantic salmon from the Ste. Marguerite River, Que. Tissue samples were obtained fish caught in the sport fishery during the summers of 1995 (n = 33) and 1996 (n = 28) and measured by gamma spectrometry. Dashed vertical lines denote the expected range in 137Cs concentrations in salmon based on a mean bioaccumulation factor of 130 from waters in the North Atlantic outlined in the color bar above (water 137Cs concentrations color coded as in the first figure). Horizontal lines denote the observed ranges in 137Cs concentrations in salmon and other fish (cod, whiting, haddock, hake, mackerel, and plaice) caught in those same waters.
The range of activities found in the migratory Atlantic salmon is similar to the range seen for other species of fish across the North Atlantic and suggests that almost half of the Ste. Marguerite salmon spent their lives feeding in waters near to Norway and the UK. This is an amazing result and suggested that more fish spend more time in the eastern Atlantic than was thought at the time. The levels seen in the salmon agree well with predictions based on seawater activities and the expected bioconcentration factor in the food web to salmon of ~130. You can read more about bioconcentration of radionuclides and concentration factors in marine organisms in one of my earlier posts here.
What does this tell us about expected contamination from Fukushima in Pacific Salmon and health risks to consumers?
The maximum seawater concentration of 137Cs in the central and eastern North Pacific we have measured through the InFORM project is about 7 — 10 Bq m-3. Given the bioconcentration expected from previous studies of salmonid species like Tucker and colleagues above we might expect maximum contamination levels in Pacific salmon of ~ 1.3 Bq kg-1 wet weight. The range of values we have detected in Pacific species returning to British Columbia rivers and streams since the Fukushima disaster in 2011 is ~0.20-0.60 Bq kg-1 suggesting that these fish have consumed prey and lived in waters with seawater activities <10 Bq m-3. At present the levels of Fukushima derived contamination do not lead to ionizing radiation doses to consumers that remotely approach the dose attributable to naturally occurring radioisotopes like 40K and 210Po. The ionizing radiation dose from the naturally occurring isotopes do not approach levels where significant risks to the health of consumers are to be expected. Given what the scientific community understands about bioconcentration of the most radiologically significant isotopes released from Fukushima and measured and forecast levels of these isotopes in the expansive North Pacific the community has confidence that levels in Pacific salmon species will not approach levels were risk to consumers will become significant. The InFORM project will continue to monitor contamination levels in seawater and the marine biota to provide accurate information and useful, scientifically derived assessment of risk to the public.
With the exception of 7 fish discussed in point 3 below individual fish were not found to have detectable levels of either 134Cs or 137Cs so average levels were calculated for all fish harvested in a given location.
Similar to 2014, none of the fish from 2015 analyzed thus far were found to contain detectable levels of 134Cs a man-made radionuclide that serves as a fingerprint of the Fukushima disaster.
The average level of 137Cs seen in InFORM 2015 fish samples (0.19 Bq kg-1) is similar to the level observed in the 2014 campaign (0.21 Bq kg-1). As with 134Cs, the Fukushima disaster resulted in the release of a large quantity of 137Cs. However, 137Cs, which has a longer half-life, was already present in the Pacific Ocean prior to the Fukushima accident because of the nuclear weapons testing fallout.
The 137Cs levels observed in the 2015 InFORM samples represent a fraction of the Health Canada guidelines (1000 Bq kg-1) and a fraction of the radiation exposure owing to naturally occurring radionuclides Polonium-210 (210Po) and Potassium-40 (40K) which dominate the ionizing radiation dose to fish consumers.
While the average 137Cs concentration remained nearly identical from 2014 to 2015, 7 individualfish (out of 156) have shown a detectable level of 137Cs (ranging from 0.27 to 0.60 Bq kg-1) while individual fish from 2014 were below detection limit. Because no 134Cs was detected in these fish it is not possible to say whether detectable 137Cs can be attributed to Fukushima contamination or simply normal variability in contamination owing to nuclear weapons testing fallout.
What this means is that radioactivity from the Fukushima meltdowns has not been detected in the InFORM fish samples caught in BC waters as of summer 2015.
Neither the 137Cs present in the fish nor the naturally occurring radioisotopes in fish represent a measurable health risk to consumers in Canada.