Dr. Trevor J. Stocki Colloquium

Fri. Dec. 2 12:30 PM - Fri. Dec. 2 01:20 PM
Location: 3M69

Dr. Trevor J. Stocki

Research Scientist/Adjunct Professor

Radiation Protection Bureau, Health Canada/Carleton University

From the 1960s Fallout to Fukushima: A look at Cesium in the Canadian Arctic

Following the Fukushima Daiichi nuclear accident in March 2011, northern Canadians expressed concerns about the levels of radioactive contaminants in important traditional foods. Therefore, a study has been conducted to measure the levels of radionuclides in Arctic caribou and beluga whales.  The main radionuclide of concern is cesium-137, which has a half-life of 30 years and is chemically similar to potassium, thereby easily accumulating in plants and animals.  This talk will review sources of cesium-137 in the environment, including atmospheric releases during nuclear weapons tests in the 1950s-60s and nuclear accidents, such as the crash of Cosmos 954, Chernobyl, and, most recently, Fukushima Daiichi. The cesium-137 levels in Canadian caribou herds were previously studied from 1958 to 2000, thereby allowing researchers to determine the amounts specifically attributable to atmospheric weapons testing and to the Chernobyl accident.  As a result, it is possible to characterize the incremental increase of cesium-137 in caribou due to the Fukushima Daiichi nuclear accident. Samples of lichens, mushrooms, caribou and beluga whales taken before and after the Fukushima accident were freeze dried, homogenized, and measured using gamma ray spectroscopy to identify the radionuclides present and determine the radioactivity concentration in the samples. To determine the efficiency of the detectors for the different-sized samples, physical calibration standards were used and virtual simulations were also performed.