Category Archives: Strontium

Dramatic Decrease of Fukushima Derived Radionuclides in the Northwest Pacific Ocean 2011-2012

By Jay T. Cullen

A schematic view of the formation and subduction of mode waters in the North Pacific

The purpose of this diary is to report on a recently published (Jan 2015) open-access, peer reviewed study which examined the activities of 137Cs (half life 30.2 yr), 134Cs (half life ~2.1 yr) and 90Sr (half life ~28.8 yr) in the northwest Pacific off the coasts of Japan and China. The diary is part of a ongoing effort to communicate the results of scientific research into the impact of the Fukushima Dai-ichi nuclear disaster on environmental and public health. Men and colleagues report on how activities of these fission produced isotopes changed between three research expeditions in June 2011, December 2011 and June 2012. Activities in seawater decreased dramatically through time for all three isotopes consistent with very high release rates measured from the Fukushima site in March-April 2011 followed by ongoing but many orders of magnitude (10,000 – 100,000 fold) lower releases from the site thereafter. By 2012 the impact of the Fukushima releases could be still be detected in most samples for Cs isotopes however 90Sr distributions were much more uniform with the highest measured activity only slightly above the pre-Fukushima background. These results are consistent with:

  1. the relatively small source term for 90Sr from compared with the Cs isotopes from Fukushima as determined by measurements of air, soil and water after the disaster
  2. the much lower Fukushima derived activities for these isotopes in the eastern Pacific off of North America being measured given decay and mixing of the contamination as it is transported by ocean currents

Continue reading Dramatic Decrease of Fukushima Derived Radionuclides in the Northwest Pacific Ocean 2011-2012

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Comparing the Environmental Impacts of the Chernobyl and Fukushima Disasters

Estimated total atmospheric source term for Fukushima compared to Chernobyl in PBq (PBq = 10^15 Bq). From Steinhauser et al. (2014) SciToTEnviron

By Jay T. Cullen

This post reports on a recently published peer reviewed study by Steinhauser and colleagues in the journal Science of the Total Environment (behind pay wall) comparing the Chernobyl and Fukushima nuclear accidents. The post is part of an ongoing effort to communicate the results of scientific studies into the impact of the Fukushima disaster on the environment. A majority of the radioactivity released from both Chernobyl and Fukushima can be attributed to volatile radionuclides (noble gases, iodine, cesium, tellurium). In contrast, the amounts of more refractory elements (including actinides like plutonium), released by Chernobyl was ~four orders of magnitude (10,000 fold) higher than releases from Fukushima. The most cited source term for Chernobyl is 5300 PBq (excluding noble gases) while a review of published studies of Fukushima carried out by the authors above allow an estimate for the total atmospheric source term of 520 (a range of 340–800) PBq. Monitoring of air, soil and water for radionuclides after the respective accidents indicate that the environmental impact of Chernobyl is likely to be much greater than the Fukushima accident. The post is relatively information dense as I have provided data tables for those who are interested in the estimates and the peer-reviewed studies from which they come. Apologies up front to those who find such information tedious. Continue reading Comparing the Environmental Impacts of the Chernobyl and Fukushima Disasters

What Controls Levels of Fukushima Radioisotopes in Marine Organisms?

By Jay T. Cullen

This post is part of an ongoing effort to communicate the risks to people living on the west coast of North America resulting from the ongoing release of radionuclides from the Fukushima-Daiichi nuclear power plant after the Tohoku earthquake and subsequent triple reactor meltdowns in March 2011. The purpose of this post is to explain how the concentration of radionuclides in seawater impacts the amount of radioactive elements taken up by the marine biota.

The goal is to answer questions like:

How high can we expect radioactive element concentrations to get in marine organisms?

What might be the exposure of marine organisms and human consumers of these organisms to Fukushima sourced radionuclides?


Continue reading What Controls Levels of Fukushima Radioisotopes in Marine Organisms?

Release, Dispersion and Fate of Radioactive Strontium From Fukushima in the Northwest Pacific Ocean

By Jay T. Cullen

The purpose of this diary is to summarize recent models and measurements of the release of strontium-90 (90-Sr, half life 28.8 yr) to the ocean resulting from the triple meltdowns at the Fukushima-Daiichi nuclear power plant in March 2011. This post is part of an ongoing series aimed at understanding the impact of the disaster on the North Pacific Ocean and residents of the west coast of North America. 90-Sr is a beta-emitting element that is a radiological health concern given its relatively long half life and similar chemistry to the nutrient calcium (Ca). Previous peer-reviewed work indicate that releases of 90-Sr were about 30-10,000 fold less than 137-Cs and similar to the release of 90-Sr from the Chernobyl disaster in 1986 and about 600-fold lower than the releases from atmospheric weapons tests that peaked in the mid-1960’s. Given maximal release rates after the disaster, modeled activities of 90-Sr in the marine foodweb and in fish that accounts for bioconcentration and accumulation predict maximal dose rates from Fukushima to human consumers three orders of magnitude less than doses owing to the presence of 137-Cs in marine products and thus well below maximum dose limits thought to be detrimental to public health. Continue reading Release, Dispersion and Fate of Radioactive Strontium From Fukushima in the Northwest Pacific Ocean

Comparing 20th Century Strontium and Cesium Isotopes From Atmospheric Weapons Testing in the Pacific to Fukushima Sources

by Jay T. Cullen

The purpose of this post is to compare the concentrations of Sr-90 and Cs-137 in the North Pacific Ocean over the last 50 years to the concentrations predicted to arrive on the west coast associated with waters affected by release of radionuclides from the Fukushima-Daiichi Nuclear Power Plant. Given present levels that are being measured in the eastern Pacific and barring release rates that significantly exceed past rates in March-April 2011, when release rates were 10,000-100,000 times greater than ongoing releases at the plant, the impact on marine organisms and the marine environment is likely to be less significant than impacts owing to radioactivity in the 20th century. What follows is a comparison of the concentrations measured and predicted over much of the Pacific owing to Fukushima to the concentrations that were present in the mid-1960s from the fallout of atmospheric weapons testing that is free from any discussion of safe doses or models of radiation exposure to organisms.

Continue reading Comparing 20th Century Strontium and Cesium Isotopes From Atmospheric Weapons Testing in the Pacific to Fukushima Sources