Category Archives: Seawater

Biota, British Columbia, Cesium, Citizen Science, Coastal, Isotope, Marine Life, Monitoring, N Pacific, NE Pacific, North America, Oceanic, Sample type, Seawater, Uncategorized

Insignificant Environmental and Public Health Risk from Fukushima in North America 8 Years On

March 11, 2019 fukushimainform Leave a comment

By Jay T. Cullen

Summary infographic for the Fukushima InFORM project including our measurements in North America, Japanese measurements, historical data and safety guidelines.

I am writing this post is to bring the public up to date on monitoring efforts of my research program into the impact of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on environmental and public health here in North America. This post is part of an ongoing series summarizing work carried out by the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project. Eight years since the peak in releases to the environment our project continues to measure radioisotopes released from the FDNPP that have the potential to present radiological health risks to living things. InFORM makes measurements of levels in seawater and common marine organisms as consumption of seafood is one of the most likely ways that residents of North America could be exposed to Fukushima derived contamination. We have found that:

Maximum contamination levels in seawater from Fukushima measured in waters offshore (~1500 km) and onshore British Columbia are now known to be about 8 to 10-fold lower than levels present in the North Pacific during the height of atmospheric nuclear weapons testing in the 1950’s and 1960’s. These levels are roughly 1000-fold below the maximum allowable drinking water standards for these isotopes.
Levels in Pacific salmon returning to North America have not changed in a statistically significant way since before the disaster and are lower than peak levels measured in the 1960’s.
As was reported in 2015 in this comprehensive study by Health Canada and backed up by measurements made by the international scientific community the release of radioisotopes from Fukushima will have no measurable impact on the health of the marine ecosystem in the northeast Pacific nor on public health in North America.

Eight years after this disaster it is important to remember those lost in the tsunami and those still displaced from their homes and communities struggling to recover.

Offshore and Onshore Citizen Science Monitoring of Seawater Contamination

The levels of radionuclide contamination in seawater is important to understand as the levels that ultimately are found in marine organisms is set by seawater levels. InFORM recently published a peer-reviewed paper in Environmental Science and Technology summarizing our results to date. Offshore levels of Fukushima derived isotopes have peaked and are now decreasing at our westernmost stations 1000-1500 kilometers from the North American coast. The peak levels are well below levels measured in the same waters during the 1950’s and 1960’s when atmospheric nuclear weapons tests were common. Our study area is shown in the figure below along with the prevailing currents that brought the contaminated seawater to North America.

Study area showing the onshore-offshore sampling line occupied by the InFORM project with the support of Department of Fisheries and Oceans Canada. Station P26 is ~1500 kilometers from the coast of North America.

Every month since about December 2014 volunteer citizen scientists in 15 coastal communities up and down the shores of British Columbia have collected seawater samples at the beach and returned them to our laboratories for analysis. The sampling network is shown below.

Coastal seawater monitoring stations in British Columbia.

Since monitoring began coastal seawater concentrations have increased as the Fukushima contamination plume arrives. For the first time we can report that contamination levels have ceased increasing near the coast and are beginning to diminish. The activity of ¹³⁷Cs leveled off at ~4 Bq per cubic meter of seawater which is about 2-4 times the background from weapons testing that existed here before Fukushima. Both the open ocean and coastal monitoring data are summarized in the figures below.

Monthly averaged ¹³⁷Cs detected in seawater in Bq per cubic meter collected along the coast of BC from 2014-2018.

Levels of ¹³⁷Cs in seawater (Bq per cubic meter) measured in samples collected by our citizen scientists along the BC coast compared to maximum levels measured offshore, weapons testing fallout maximum activities in the eastern Pacific in early 1960’s and Canada’s action level for the isotope in drinking water.

Offshore levels of ¹³⁷Cs peaked at a little less than 10 Bq per cubic meter and have been diminishing as less contaminated water moves across the Pacific from the west. Coastal activities have peaked at lower levels likely because freshwater runoff from the continent is less contaminated than the seawater and dilutes the Fukushima contamination.

Monitoring of Pacific Salmon

Since 2014 we have collected and analyzed ~100 Pacific salmon and steel head trout per year returning to rivers up and down the BC coast from the Pacific Ocean. There has been no statistically significant increase in the levels of human-made isotopes in the fish since before the Fukushima disaster. Below we plot the maximum levels we have detected in fish returning to BC from 2011-2017 compared to levels measured in Pacific salmon during the 1960’s when weapons fallout levels were highest surface waters.

Radiation%20in%20NE%20Pacific%20Salmon%20through%20time_max-01.png — Maximum levels of ¹³⁷Cs detected in BC salmon post Fukushima compared to levels in Pacific salmon in the mid-1960’s owing to weapons testing fallout.

On average our Pacific salmon have ~0.2 Bq per kilogram wet weight and it is important to note that there is no statistically significant different in the average contamination level in the fish in years 2011-2017. We are only showing the maximum value detected in each year and have not shown how much variability exists in the yearly data for clarity. Levels of contamination in the 1960’s were >10-fold higher than our average levels in years post-Fukushima. The dose of ionizing radiation experienced by consumers of Pacific fish and shellfish is still dominated by the presence of naturally occurring radioisotopes in the Uranium and Thorium decay series (principally 210-Polonium) and remains well below levels that might represent a health risk.

We will continue our monitoring efforts likely through the end of this calendar year and continue to report our results as they are generated. As always I am happy to answer any questions related to the project and our findings.

Cesium, Isotope, Location, NW Pacific, Peer Reviewed, Sample type, Seawater

Update: Fukushima Derived Contamination in Pacific Surface Water Up Until 2017

October 28, 2018 fukushimainform Leave a comment

Northeast subarctic Pacific from the deck of the Canadian Coast Guard Ship J.P. Tully in September 2

By Jay T. Cullen

The purpose of this post is to summarize a recently published, peer-reviewed study that documents levels of Fukushima derived contamination in surface waters of the Pacific Ocean. This post is part of an ongoing series aimed at communicating scientifically derived information about the impact of the disaster on marine environmental and public health. Michio Aoyama and colleagues measured the activity of Cesium-137 (¹³⁷Cs, half life ~30 years) and Cesium-134 (¹³⁴Cs, half life ~ 2 years) in seawater collected from the western Pacific Ocean including waters off the coast of Fukushima Prefecture from 2011-2017. They found the following:

Contamination decreased dramatically and rapidly in waters offshore of the Fukushima Daiichi Nuclear Power Plant (FDNPP) from maximum values of ~3000 Becquerel per cubic meter (Bq m^-3) of seawater in 2011 to values in 2015-16 of ~2-3 Bq m^-3. This precipitous decline is consistent with the ongoing but relatively low rates of release of radionuclides from the site compared to the bulk of contamination that was released in March-April 2011.

Levels of ¹³⁷Cs close to FDNPP now are similar to levels of contamination present there before the disaster occurred (1.5-2 Bq m^-3) owing to atmospheric nuclear weapons testing in the middle of the 20^th century.

Levels in the western Pacific were around 1-7 Bq m^-3 in 2011-2012 but stabilized at lower values in 2017.

**Levels being measured in nearshore and offshore waters in the western Pacific near to Japan do not approach levels known to represent a credible risk for ocean or public health**. These results in the western Pacific are consistent with what the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project is finding in the eastern Pacific off of North America.

Aoyama and others recently published their study in the Journal of Environmental Radioactivity. The collected and analyzed surface seawater for the presence of radiocesium isotopes between 2011 and 2017 in waters of the western Pacific in the following locations:

Boundaries of areas (boxes) sampled by Aoyama et al. (2018) in the western and central Pacific Ocean.

The activity of ¹³⁷Cs and ¹³⁴Cs in Bq m^-3 with time that they found are summarized in the following figure:

Long term trends (2011-2017) in radiocesium activity in boxes defined in the first figure. Solid blue squares are ¹³⁷Cs activity concentration and open red circles represent ¹³⁴Cs.

The researchers found that in Box 2 (closest to the FDNPP) contamination in surface waters offshore were highest in early 2011 coincident with the largest releases from the site in March-April of that year when the vast majority of radionuclides were released to the atmosphere and directly to the ocean. Values dropped dramatically so that by 2014-2016 levels were ~3 Bq m^-3 and similar to levels of contamination measured before the disaster occurred owing to nuclear weapons testing that occurred in the 1950s-60s. Note that the concentrations of ¹³⁴Cs diminish relative to ¹³⁷Cs, and the red symbols on the figure diverge from the blue symbols, because ¹³⁴Cs has an ~2 year half life and is decaying away from the environment much more rapidly. Indeed, it is becoming increasingly challenging analytically to detect Fukushima ¹³⁴Cs in environmental samples. Contamination farther offshore in Boxes 4-6 indicate that maximum levels of contamination from Fukushima approached by did not exceed 200 Bq m^-3 in 2011 and are now ~2-3 Bq m^-3.

Based on best estimates of how much radiocesium was released from FDNPP in March-April 2011 the authors used a model of the water circulation and mixing in the Pacific to predict the levels and movement of Fukushima ¹³⁴Cs in the Pacific from April 2012 until October 2016. The results of the modeling study are summarized in the following figure:

Horizontal distribution of ¹³⁴Cs from Fukushima for the period April 2012 to October 2016. Open circles represent observations/measurements of ¹³⁴Cs while shading reflects model results.

What the model and observations indicate is that the bulk of contamination from the site went into the Pacific Ocean in 2011 and that rates of release from the site after that time are very small in comparison. Most of the Fukushima contamination is now in the eastern Pacific near to North America and that levels in behind the main body of contamination are difficult to detect. Similarly, the lack of appreciable ¹³⁴Cs and ¹³⁴Cs/¹³⁷Cs activity ratios close to FDNPP indicate that there is little evidence for ongoing fission in the reactors at the site as is commonly speculated by those with little scientific training. The levels the scientific community is measuring close to FDNPP and those expected and measured in waters close to North America do not represent a significant risk to the marine ecosystem or public health.

The Fukushima InFORM project will continue its monitoring activities in the eastern Pacific until Spring 2019.

Continue reading Update: Fukushima Derived Contamination in Pacific Surface Water Up Until 2017 →

Cesium, Fukushima, Japan, Marine Life, Peer Reviewed, Plutonium, Seawater, Sediment, Strontium

IAEA Affirms Japan’s Fukushima-Related Radioactivity Monitoring

October 11, 2017 dr.jonathan.kellogg Leave a comment

by Tim Hornyak
11 October 2017
Originally published by Eos, a periodical of the American Geophysical Union

Laboratories outside Japan have validated the results. Marine radioactivity levels from the nuclear disaster have fallen, but questions remain years after the meltdown. Continue reading IAEA Affirms Japan’s Fukushima-Related Radioactivity Monitoring →

British Columbia, Citizen Science, Location, Sample type, Seawater

Citizen Scientists Sampling for Fukushima Contamination in Port Renfrew BC (August 2016)

November 3, 2016 fukushimainform Leave a comment

by Jay T. Cullen

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).

Cesium, Fukushima, Japan, N Pacific, NE Pacific, NW Pacific, Peer Reviewed, Seawater

Open Access Review of Fukushima Radionuclide Source Term, Fate and Impact in Pacific

July 12, 2016 dr.jonathan.kellogg 1 Comment

Schematic of Fukushima Daiichi sources of 137-Cs from Buesseler et al. (in press). Atmospheric fallout (1) and direct ocean discharges (2) represent total petabecquerels (PBq = 10^15 Bq) released in the first month of the meltdowns. Groundwater fluxes (3) and river runoff (4) are approximate ranges for the first year in terabecquerels (TBq = 10^12 Bq), a unit 1,000 times smaller than the PBq used for fallout and direct discharge. Details on source term estimates can be found in the paper (http://www.annualreviews.org/doi/abs/10.1146/annurev-marine-010816-060733). (Buesseler et al. 2017)

by Jay T Cullen

The purpose of this post is to bring to the attention of readers here a review of the available measurements and science based investigations of the Fukushima Daiichi Nuclear Power Plant (FDNPP) and its impact on the Pacific Ocean ecosystem and public health. This post is part of an ongoing effort to summarize scientifically rigorous information about the disaster for interested readers. The new paper is a product of a working group on radioactivity in the ocean convened by the Scientific Committee on Ocean Research (SCOR) an international non-governmental non-profit organization. I highly recommend this paper for anyone who wishes to better understand what the international scientific community has found about the marine release, fate and impact of FDNPP-derived radionuclides in the marine environment. The working group was made up of 10 experts from 9 different countries, including Japan, and published the open access paper in Annual Reviews. The main findings of the review were as follows:

The amount of ¹³⁷Cs released from the plant was ~50-fold less than the fall out from nuclear weapons testing in the 20^th century and ~5-fold lower than that released from Chernobyl in 1986. Total releases from Fukushima are similar to the discharges of ¹³⁷Cs from the nuclear fuel reprocessing plant Sellafield in the UK
Initial releases in the weeks to months after the disaster which began on March 11, 2011 dwarf those from aggregated ongoing releases from the plant site
The majority of radionuclide releases ended up in the Pacific Ocean with most deposition and input occurring close to the FDNPP
Current range of estimates of the total ¹³⁷Cs ocean source term are 15-25 PBq (PBq = 10¹⁵ Becquerel where a Bq is one nuclear decay event per second). While many other radionuclides were released from FDNPP, the most likely isotopes to represent a health risk to the marine ecosystem and public are those of Cs given their longer half-lives for radioactive decay (¹³⁴Cs = ~2 yrs; ¹³⁷Cs = ~30 yrs) and higher relative abundance compared to other isotopes of concern in the FDNPP source term
Because Cs is very soluble it rapidly dispersed in the ocean after the disaster given mixing, transport and dilution by ocean currents. Peak levels of ¹³⁷Cs occurred close to the plant in 2011 where activity concentrations near FDNPP was tens of millions of times higher than before the accident. By 2014 ¹³⁷Cs concentrations in the central North Pacific was about six times the remaining weapons testing fallout and about 2-3 times higher than prior fallout levels in the northeast Pacific near to North America. Most of the fallout remains concentrated in the top few hundred meters of the ocean. Measurements being made by the Fukushima InFORM project indicate that maximum ¹³⁷Cs levels off the North American coast are likely to occur this year before declining to levels associated with background nuclear weapon testing before the accident by about the end of this decade
There are unlikely to be measurable effects on marine life with the exception of coastal areas very close to FDNPP immediately after the disaster. Monitoring of fish species in Fukushima Prefecture show that about 50% of samples in coastal waters had radiocesium levels above the Japanese 100 Bq kg^-1 limit, but that by 2015 this had dropped to less than 1% measuring over the limit. High levels continue to be found in fish around and in the FDNPP port
Given levels in seawater and marine organisms measurable impacts to human health through contact with the ocean and the consumption of seafoods are very unlikely

There are many informative graphics and moderately technical summaries of available studies found in the new paper. The authors highlight the difficulty of monitoring radionuclides in the ocean given the dynamic nature of the sea and logistical challenges presented by the temporal and spatial scales and low levels of FDNPP derived contamination going forward. In addition to providing ongoing assessments of risk to the environment from the disaster it is likely that useful information about ocean circulation will be obtained through continued monitoring efforts.