The purpose of this post is to review how the background dose of ionizing radiation has changed through geologic time until the present. I was motivated to write this by questions and misinformed statements made to me regarding the likelihood that the low levels of ionizing radiation now added to the Pacific Ocean might harm marine microbes and effectively kill the base of the oceanic food chain – given levels being measured this is for all intents and purposes impossible. This post is part of an ongoing series that summarizes the results of scientific research into the impact of the Fukushima Dai-ichi nuclear disaster on the health of the marine environment and residents of the west coast of North America. Life on Earth has been exposed to ionizing radiation since the first organisms began leaving chemical signs of their existence almost 4 billion years ago. In a paper published in 1999 Karam and Leslie calculated how the dose experienced by organisms from naturally radioactive geological and biological materials has changed over time. They find that overall the annual beta and gamma dose experienced by organisms has dropped from about 7 millisievert (mSv = 0.001 Sv) 4 billion years ago to about 1.4 mSv today. Given the similarity of repair mechanisms that organisms use to cope with damage from ionizing radiation it is likely that these mechanisms evolved early in Earth’s history which may explain why organisms are capable of dealing with higher than background doses in the environment today. Continue reading Background Ionizing Radiation Dose Through Geologic Time
Tag Archives: Natural radiation
Analysis of Beached Grey Whale in British Columbia for Fukushima Radioisotopes
By Jay T. Cullen
The purpose of this post is to report analyses carried out by the InFORM project on muscle and blubber samples from a grey whale (Eschrichtius robustus), that beached near Tofino, BC on April 20, 2015. The post is the most recent in a series that aims to communicate results of scientific research into the impact of the Fukushima disaster on the environment. With the cooperation of the Ucluelet Aquarium the InFORM project was able to obtain samples of the whales muscle and blubber which were analyzed for the presence of gamma emitting radioisotopes in Health Canada’s laboratories in Ottawa, ON Canada. The gamma radiation spectra were dominated by naturally occurring radioisotopes, primarily Potassium-40 (40K half life 1.25 billion years), and after 24 hours of counting no Fukushima derived Cesium-134 (134Cs half life ~ 2 years), a fingerprint of the disaster in the environment could be detected. The unfortunate demise of the grey whale is very unlikely to have been the result of acute or chronic radiation exposure owing to Fukushima derived radionuclides in seawater and the whales food. Continue reading Analysis of Beached Grey Whale in British Columbia for Fukushima Radioisotopes
How Much Radioactivity Are We Exposed to While Sampling Seawater for Fukushima Radioisotopes?
The purpose of this post is to introduce a brief, informal movie made while using a Geiger Counter in the laboratory today. This diary is part of an ongoing effort to communicate what the scientific community is learning about the impact of the Fukushima disaster on environmental and public health. A Geiger Counter was used to examine ionizing radiation counts per minute in the laboratory owing to background radioactivity, the concentrated natural and man made isotopes in 20 liters of seawater collected by InFORM citizen scientist volunteers, the uranium oxide glaze on a Fiestaware dinner platter and Uraninite ore mined from New Hampshire. This simple demonstration supports more sensitive measurements indicating our citizen scientists are exposed to no more ionizing radiation than is typical of background when collecting seawater samples.
How do Radiation Activities Relate to Contaminant Concentrations?
The purpose of this post is to give a brief overview of how the activity of radionuclides correspond to the concentration of radionuclides measured in environmental samples. There appears to be some confusion in the public and within the scientific community as to how units are used and the degree of their interchangeability. This post is somewhat technical but falls into the category of “In Case You’re Interested” (ICYI), an acronym I am shamelessly borrowing from a fine book (Everything and More: A Compact History of Infinity) by one of my favorite writers David F. Wallace.
Continue reading How do Radiation Activities Relate to Contaminant Concentrations?
What Controls Levels of Fukushima Radioisotopes in Marine Organisms?
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?
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