New measurements suggest oceanic radioactivity from the 2011 Fukushima power plant meltdown will most likely peak off the coasts of the U.S. and Canada by next year before fading to very low levels.
The researchers found cesium-137 (the longest-lived of the two forms of cesium released in the disaster and the primary concern of the study) levels will most likely remain below what has been determined to be safe in drinking water by the U.S. and Canadian governments ,even when the radiation reaches its peak, the Christian Science Monitor reported.
To make their findings the researchers expanded on research conducted last year and described at the ocean-sciences meeting in Hawaii. The findings looked at data gathered between 2011 and 2013 from 26 sampling sites that began at the Juan de Fuca Strait and moved over 1,000 miles westward. The researchers looked at levels of both cesium-134 and cesium-137 in the water samples.
The findings suggest the radiation levels will reach between 3 and 5 Becquerels per cubic meter of water at peak; Canada's current drinking water standard for cesium-137 is 10,000 Becquerels per cubic meter.
"The radionuclide results in this report represent the first systematic study, to our knowledge, of the arrival of the Fukushima radioactivity signal in continental waters off North America. The present time series results are critical to an understanding of the circulation of Fukushima tracers in the eastern North Pacific and to the tuning and validation of ocean circulation models that are being used to predict the future evolution of this signal," the researchers wrote in their study abstract.
The team noted the findings could also help keep the general public informed about the magnitude of the disaster's effects and allow a "science-based" assessment of the potential influences it will have on human health and the environment.
The findings were published in a recent edition of the Proceedings of the National Academy of Sciences (PNAS).
