When the tsunami triggered the explosions at the Fukushima Nuclear Power Plant in Japan, we all worried about the release of radioactivity to the environment. Indeed, just a few days later, increased levels of radioactive cesium were measured in rainfall along the west coast of the United States. Public Health officials assured us that, while measurable, this radioactive fallout did not pose a human health hazard.
The release of radioactivity at Fukushima is thought to be about 10% of that released at Chernobyl. Containment structures prevented the release of highly dangerous isotopes of strontium-90 and plutonium. Iodine-134 was released to the atmosphere, but it decays rapidly, so there was little human exposure. The isotopes of greatest significance were cesium, which was soon detected in fish off the coast of Japan, prohibiting its consumption.
Now, two years later, a group of oceanographers has examined the distribution of cesium-137 some 25 miles from Japan’s coast, where they find that it is enriched more than a thousand times above background levels. This isotope has mixed down to a depth of 300 meters in the ocean.
These cesium levels are of some concern for human health, and they speak strongly about the underlying problems associated with nuclear power generation. The medical community finds genetic damage at all levels of radiation down to zero. Just how much should worry us?
Meanwhile, oceanographers have a new tracer for studies of the movements of water in the deep sea, in which these isotopes can now be followed for centuries.
**********
Web Links
For more information, please see: Povinec et al. 2013. Biogeosciences Discussin 10: 6377-6416
Photo, taken on December 25, 2011, courtesy of Hajime Nakano via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY, with partial support from the Field Day Foundation.