Category Archives: Monitoring

Observing the Arrival of the Fukushima Contamination Plume in North American Coastal Waters

By Jay T. Cullen

@JayTCullen and @FukushimaInFORM

This short blog summarizes an open access paper published today reporting results from a Canadian monitoring program tasked with documenting the arrival of ocean borne Fukushima contamination along the North American Pacific coast. This diary is part of an ongoing effort to communicate the best science available on the impacts of the Fukushima Dai-ichi meltdowns on the environment. High quality measurements to look for Fukushima derived radiocesium were made in seawater in the North Pacific and Arctic Oceans from 2011 to early 2014. The authors concluded that:

  1. Fukushima derived radiocesium was first detected 1500 km west of British Columbia Canada in June 2012
  2. Contamination was detected on the continental shelf (near coastal waters) in June 2013
  3. By February 2014 Fukushima radiocesium was present at levels similar to preexisting weapons testing derived 137-Cs
  4. The timing of the arrival and levels of radiocesium in the contaminated plume are in reasonable agreement with existing ocean circulation model predictions
  5. These same models predict that total radiocesium levels from weapons testing fallout and Fukushima will likely reach maximum values of ~3-5 Becquerel per cubic meter (Bq m-3 of seawater in 2015-2016 and then decline to fallout background level of ~1 Bq m-3 by 2021
  6. Fukushima will increase northeastern Pacific water to levels last seen in the 1980’s but does not represent a threat to environmental or human health

Continue reading Observing the Arrival of the Fukushima Contamination Plume in North American Coastal Waters

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First Seawater Monitoring Result From Victoria, BC: No Fukushima Contamination as of Oct. 15, 2014

By Jay T. Cullen

@JayTCullen and @FukushimaInFORM

On the granite blocks that make up the south side of Ogden Point Breakwater getting ready to take the first InFORM sample (photo by Katherine Maas)
On the granite blocks that make up the south side of Ogden Point Breakwater getting ready to take the first InFORM sample (photo by Katherine Maas)

What we found:

137-Cesium activity = 1.3 (+/- 0.1) Bq m-3 (Becquerel per meter cubed of seawater)
134-Cesium activity = Not Detected
Water Temperature = 10.5 C

The InFORM team collected a seawater sample in collaboration with citizen scientists in Victoria on Wednesday, Oct. 15 at the Ogden Point Breakwater (map shown below).  The sample was processed and the amount of gamma emitting isotopes determined using a high purity germanium detector.  We look primarily for radioisotopes of cesium (134-Cs half life ~2 years and 137-Cs half life ~ 30 years) for the following reasons: Continue reading First Seawater Monitoring Result From Victoria, BC: No Fukushima Contamination as of Oct. 15, 2014

Monitoring Results For Sockeye Salmon and Steelhead Trout Collected Summer 2014

The Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project is a network involving academic, governmental, and non-governmental organizations, as well as citizen scientists. InFORM is acquiring data to support a thorough radiological impact assessment for Canada’s west coast stemming from the Fukushima Dai-ichi nuclear power plant (FD-NPP) accident, and to effectively communicate these results to the public. The first measurements undertaken as part of the InFORM project to look for Fukushima derived radionculides were made on 19 fish in collaboration with the Nisga’a First Nation. Sockeye salmon (Oncorhynchus nerka) and Steelhead Trout (Oncorhynchus mykiss) were caught off the west coast of Canada in Summer 2014 as they were returning to the Nass River in northern BC.

Measurements of radioactive elements in these fish are reported in the data table below and are available for download through Health Canada:

Sample

137-Cs (Bq/kg)

134-Cs (Bq/kg)

40-K (Bq/kg)

210-Po (Bq/kg)

Steelhead #1

< 1.5

< 1.3

155 (23)

 

Steelhead #2

< 1.4

< 1.3

136 (21)

 

Steelhead #3

< 1.4

< 1.4

126 (22)

1.7 (0.5)

Steelhead #4

< 1.4

< 1.3

146 (22)

 

Steelhead #5

< 1.4

< 1.4

135 (21)

 

Steelhead #6

< 0.9

< 1.8

158 (29)

 

Steelhead #7

< 1.3

< 1.3

125 (21)

 

Steelhead #8

< 1.4

< 1.3

113 (20)

1.3 (0.4)

Steelhead #9

< 1.5

< 1.4

136 (21)

 

Steelhead #10

< 1.3

< 1.2

113 (21)

 

Sockeye #1

< 1.9

< 1.8

187 (29)

 

Sockeye #2

< 1.4

< 1.4

175 (23)

 

Sockeye #3

< 1.3

< 1.3

148 (21)

<0.2

Sockeye #4

< 1.4

< 1.3

160 (22)

 

Sockeye #5

< 1.4

< 1.3

149 (22)

 

Sockeye #6

< 1.3

< 1.4

129 (22)

 

Sockeye #8

< 1.4

< 1.3

130 (22)

 

Sockeye #9

< 1.3

< 1.3

142 (22)

0.5 (0.2)

Sockeye #10

< 1.4

< 1.4

112 (23)

 

 

 

 

 

 

Samples Combined (average)

0.27 (0.04)

< 0.18

168 (5)

0.9 (0.3)

Numbers with “<” indicate that levels were below the detection limit of the analysis and numbers inside parenthesis “( )” report the uncertainty associated with the measurement.

What are we measuring and why?

The triple meltdowns at the Fukushima Dai-ichi nuclear power plant (NPP) released many different radioisotopes to the environment, however only a very few of these are both measurable and unique to Fukushima. A reliable finger-print radioisotope for Fukushima is Cesium-134 (134-Cs half life ~ 2 years). This is because 134-Cs is only produced in nuclear reactors and it has a relatively short half-life, so that 134-Cs from other human sources, like the Chernobyl NPP disaster in 1986, are no longer present in the environment. Other isotopes such as Cesium-137 (137-Cs half life ~30 years) are not positive indicators of Fukushima since they were also a products of atmospheric testing in the 20th century and Chernobyl and are still present in the environment from these legacy sources.

 

How scientists talk about radioactivity in the environment

Scientists use a variety of units to measure radioactivity. A commonly used unit is the Becquerel (Bq for short) which represents an amount of radioactive material where one atom decays per second and has units of inverse time (per second). Another unit commonly used is disintegrations per minute (dpm) where the number of atoms undergoing radioactive decay in one minute are counted (so 1 Bq = 60 dpm). The measurements above represent that numbers of Bq detected in a kilogram of fish flesh.

 

Measurements of Sockeye Salmon and Steelhead Trout

We measured the activities of cesium radioisotopes 134-Cs and 137-Cs that were released in large quantities from the Fukushima Dai-ichi Nuclear Power Plant disaster in 2011. We also measured naturally occurring radioisotopes Potassium-40 (40-K) and Polonium-210 (210-Po) that always contribute doses of radiation to human consumers of marine fish. Samples of sockeye salmon and steelhead returning to the Nass River in northern BC, obtained from the Nisga’a First Nation, were analyzed and none were found to contain detectable levels of Fukushima derived radionuclides. By adding together the signals obtained for all of the samples we calculate an average activity concentration of 0.27 Bq/kg for 137-Cs.  This represents residual 137-Cs in the North Pacific largely from atmospheric nuclear weapons testing in the last century.  At present, Fukushima derived radionuclides cannot be detected. Nuclear weapons testing fallout (137-Cs) can be detected in BC fish at levels that represent a fraction of the radiation exposure owing to naturally occurring radionuclides neither of which represent a dangerous health risk to consumers in Canada.  Results for a further ~80 fish collected this summer and fall from various returning runs up and down the BC coast will be reported as samples are analyzed.

 

The Importance of Salmon to Canadians

Pacific salmon are economically, culturally, and ecological significant species to British Columbia. On an annual basis, the commercial, recreational, and First Nation salmon fisheries contribute over $600 million in revenues. They are an important food source to First Nations and coastal communities, and numerous animal species such as endangered Killer Whales, Gray Wolf, Grizzly Bear, seabirds, and insects. They provide nutrients to freshwater ecosystems and riparian habitats through the decomposition of their carcass.

There are six species of Pacific salmon in British Columbia. During the first year of the project, InFORM will focus primarily on Sockeye Salmon (Oncorhynchus nerka) and Steelhead Trout (Oncorhynchus mykiss), though other salmon species have and will be examined. Both species typically spend 2-3 years in the North Pacific Ocean prior to returning to their natal streams and venture further west than any other salmon species (Figure 1-2). On an annual basis, 1-10 million Sockeye Salmon are commercially harvested for human consumption and ceremonial purposes. In contrast, the fishery for Steelhead Trout is primarily catch and release due to conservation concerns for this species, particularly in Southern British Columbia. Although wild Steelhead Trout are not frequently consumed in Canada, their extensive westward migration that brings them close to the coast of Japan makes them an ideal canary species for monitoring radiation levels in salmon species originating from British Columbia.

Figure 1. Approximate range for the distribution of Sockeye Salmon in the North Pacific Ocean originating from North America and Asia. Source: http://www.pac.dfo-mpo.gc.ca/fm-gp/species-especes/salmon-saumon/facts-infos/sockeye-rouge-eng.html
Figure 1. Approximate range for the distribution of Sockeye Salmon in the North Pacific Ocean originating from North America and Asia. Source: http://www.pac.dfo-mpo.gc.ca/fm-gp/species-especes/salmon-saumon/facts-infos/sockeye-rouge-eng.html

 

steelhead_trout_small
Figure 2. Approximate range for the distribution of Steelhead Trout in the North Pacific Ocean originating from British Columbia (red) and Washington, Oregon, and California (green). Source: http://www.pac.dfo-mpo.gc.ca/fm-gp/species-especes/salmon-saumon/facts-infos/steel-arc-eng.html

Technical Information Regarding Sample Analyses

  • 19 fish samples, flesh only (9 Sockeye Salmon and 10 Steelhead Trout) were obtained from the Nisga’a First Nation
  • A sub-sample of ~125g of wet mass (average wet mass (measured) = 126.67 g) was taken and placed in a sample counting container
  • Gamma-radiation emitting isotopes were measured by gamma spectroscopy using a high purity germanium detector and each sample being counted for 6 hours
    • Planar BE5030 high purity germanium (HPGe) detector with relative counting efficiency of 46%
    • counting geometry = Parkway Jar (Polyethylene, active volume = 129 mL) placed in a polyacrylate sample holder (2.95 mm thickness)
    • counting efficiency was determined by applying an empirical efficiency curve, determined from a multi-nuclide (12) standard (Eckert and Ziegler Analytics, SRS: 79535-411) of similar density (1.15 g/cm^3, Parkway Jar format) spanning energies of 46.5 – 1836.1 KeV
    • true coincidence summing (where applicable) is accomplished by extracting detailed decay scheme data from the UniSampo-Shaman nuclide library
  • Spectral summation was done by adding all the spectrum into a single one and then reanalysed using UniSampo-Shaman gamma spectral analysis software from Baryon Oy, Ltd., Finland, with decay correction to the catch date of August 28, 2014

 

Most Recent Measurements of Fukushima Derived Isotopes in the Northeast Pacific Ocean

By Jay T. Cullen

Satellite measurements of ocean temperature (illustrated by color) from July 28th to August 4th and the direction of currents (white arrows) help show where radionuclides from Fukushima are transported. Large scale currents transport water westward across the Pacific. Upwelling along the west coast of North America in the summertime brings cold deep water to the surface and transports water offshore. Circles indicate the locations where water samples were collected. White circles indicate that no cesium-134 was detected. Blue circles indicate locations were low levels of cesium-134 were detected. No cesium-134 has yet been detected along the coast, but low levels have been detected offshore. (Woods Hole Oceanographic Institution)
Satellite measurements of ocean temperature (illustrated by color) from July 28th to August 4th and the direction of currents (white arrows) help show where radionuclides from Fukushima are transported. Large scale currents transport water westward across the Pacific. Upwelling along the west coast of North America in the summertime brings cold deep water to the surface and transports water offshore. Circles indicate the locations where water samples were collected. White circles indicate that no cesium-134 was detected. Blue circles indicate locations were low levels of cesium-134 were detected. No cesium-134 has yet been detected along the coast, but low levels have been detected offshore. (Woods Hole Oceanographic Institution)

The purpose of this post is to report on new results coming out the crowd-funded Our Radioactive Ocean program headed up by Dr. Ken Buesseler of Woods Hole Oceanographic Institution. This post is part of an ongoing series dedicated to scientific inquiry into the impact of the triple meltdowns at Fukushima on the health of the North Pacific Ocean and residents of the west coast of North America. Measurements of the cesium radioisotopes 134-Cs (half life ~ 2 years) and 137-Cs (half life ~30 years) were made on samples collected on a transect between Monterey Bay CA and Dutch Harbor AK this summer. Because of its relatively short half life 14-Cs serves as an unequivocal tracer of Fukushima contamination in the environment. Fukushima derived 134-Cs was detected at offshore stations with a maximum activity of ~ 2 Bq/m^3 and total 137-Cs activities of ~7 Bq/m^3 of seawater. Measurements have yet to detect 134-Cs in nearshore waters sampled up and down the North American west coast. These activities of Cs are orders of magnitude below levels thought to pose a measurable risk to human health or marine life, according to international health agencies.


For a primer on radioactivity in the ocean and the units used to discuss radioactive elements in the environment please visit this post.

A press release from WHOI regarding these new results can be found here and details about sampling locations and activities of Cs detected are available here.

At a great majority of sites sampled along the coast and offshore the activity of 134-Cs is below detection limit (~legacy contamination resulting from atmospheric weapons testing in the 20th century. Similar to previous work by Dr. John Smith of the Department of Fisheries and Oceans Canada the presence of the contaminated plume of seawater owing to releases from Fukushima can be detected in offshore stations (150 – 1500 km) with levels of 134-Cs approaching 2 Bq/m^3 and total 137-Cs (bomb + Fukushima) of about ~7 Bq/m^3. These levels of 137-Cs are similar to levels in the North Pacific Ocean that were present in 1990 owing to the combined effects of Chernobyl and weapons testing fallout as shown in the figure below.

Activity of 137-Cs in the North Pacific after Povinec and others (2013) http://www.biogeosciences.net/10/5481/2013/bg-10-5481-2013.html with arrows indicating the impact of Chernobyl, 2008 137-Cs activity in the Irish Sea and 2014 levels offshore of western North America post Fukushima for comparison.
Activities of these isotopes were about 10 million fold higher in coastal waters near the Fukushima Dai-ichi nuclear power plant off Japan in the weeks following the beginning of the disaster in March and April 2011 when rates of release and seawater concentrations were at their peak. Current releases from the plant support seawater activities on the order of 10’s-100’s of Bq/m^3 within 2 km of the plant site. The highest activities associated with the most contaminated seawater from Fukushima are predicted to travel across the North Pacific with prevailing currents and arrive in North American waters between this year and next. These offshore activities of Fukushima derived 137-Cs of ~ 5 Bq/m^3 exceed predicted activities of ~3 Bq/m^3 suggesting that offshore activities are likely reaching near peak values. The measurements being made by the international scientific community will undoubtedly help to improve our understanding of mixing and transport in the oceans.

The activities of radiocesium being detected offshore are well below levels thought to represent significant radiological health risks to marine organisms or residents of the west coast of North America. To this point no 134-Cs from the contaminated plume approaching the coast has been detected in nearshore waters. Ongoing monitoring by programs like Our Radioactive Ocean and its partner program InFORM which are making measurements of contamination in seawater and marine organisms will be key to understanding impacts of the Fukushima on our environment.

Kelp Watch 2014 Update: No Fukushima Derived Radiocesium Detected in West Coast Kelp

By Jay T. Cullen

Dan Harrison, Executive Director of InFORM partner organization Raincoast Education Society (http://raincoasteducation.org/) sampling kelp for Kelp Watch 2014 in Tofino, BC Canada.

The most recent results of Kelp Watch 2014 , a program dedicated to monitoring for the presence of Fukushima sourced radionuclides off our Pacific Coast, are reported in this post. This post is the latest contribution to a series dedicated to the dissemination of information about the impacts of the Fukushima Dai-ichi disaster on the North Pacific Ocean ecosystem and on North American public health. New results from the second sampling period (June to August 2014) of Kelp Watch 2014 were just released and can be found here. As with previously reported results here and here no radioactive isotopes from Fukushima were detected in kelp growing at sampling sites spread across the eastern Pacific coast. However, significant quantities of the short lived radioisotope 131-Iodine (half life ~8 days) continued to be found in Los Angeles County and San Diego in southern California. Rather than being transported across the Pacific these isotopes were likely released locally in waste water that carries significant 131-I because of its application in nuclear medicine to treat thyroid maladies. The absence of 134-Cs in kelp suggest that ocean transport of Fukushima contamination has yet to reach North American coastal water.


Kelp Watch 2014 is a joint initiative between Dr. Steven Manley (Department of Biological Sciences, California State University- Long Beach) and Dr. Kai Vetter (UC Berkeley and Lawrence Berkeley National Laboratory). The program involves the analysis of kelp samples collected by citizen-scientists along the Pacific coast for Fukushima derived radioisotopes. Because of their sedentary existences and propensity to concentrate isotopes in their tissues kelp are useful sentinel organisms with which to monitor the timing and extent of the Fukushima impacted plume of seawater as it progressively affects more of the North American west coast.

Samples were collected June to August of this year at various sampling locations along the coast with some kelp obtained from Chile and Tasmania (where little Fukushima impact is expected) to serve as reference locations.

Stations where samples of kelp were obtained for Kelp Watch 2014
Full results for the second sampling period can be found here along with details about the goals and approach of Kelp Watch 2014.

Because of its relatively short half life of ~2 years radioactive 134-Cs serves as a useful tracer of Fukushima impact as it was released in significant quantities, with many other isotopes, into the environment after the disaster in March 2011. All other legacy sources of the human produced isotope have occurred far enough in the past that any 134-Cs present in the environment faithfully reflects release from Fukushima. Similar to previous work by this program all samples of kelp collected from the Pacific by Kelp Watch 2014 in June to August of this year had no detectable (detection limit ~ 0.04 Bq/kg dry weight of kelp) levels of 134-Cs suggesting that isotopes from Fukushima are not significantly affecting radioisotope activities in these organisms to date.

The authors summarize findings about 134-Cs and its longer lived cousin 137-Cs (half life ~30 yr) as follows:

Cesium-137 was detected in all West Coast samples at very low levels. This isotope is still detectable in the marine environment due to above-ground nuclear weapons testing that took place mostly in the 1950s and 1960s. The very low limits set on the shorter-lived Cesium-134 mean that the Cs-137 cannot be directly tied to the Fukushima releases and is more likely due to these “legacy” sources.

Significant Iodine-131 (131-I, half life ~8 days), which can represent a significant radiological health risk given its propensity to concentrate in the thyroid gland and induce cancer, activities continue to be detected (up to 251 Bq/kg at Long Beach CA) in southern California kelp samples. This 131-I is not likely from Fukushima given that ocean transport is quite slow relative to 131-I decay. Kelp Watch 2014 attributes the presence of 131-I to local sources which are likely waste water inputs to the coastal ocean that contains 131-I from nuclear medical applications in hospitals and clinics in the area.

Ongoing monitoring of seawater and marine organism activity concentrations of radioisotopes from Fukushima will help to determine the likely impacts on the ecosystem and public health along North America’s Pacific coast resulting from the disaster. As always, I will report new results as they are made available and we look forward to more work from this quality monitoring program.