redOrbit Staff & Wire Reports – Your Universe Online
The radioactive ocean plume created as a result of the 2011 Fukushima nuclear power plant disaster is expected to reach North America by next year, according to research appearing in the latest edition of the journal Deep-Sea Research 1.
Fortunately, the study authors report the plume will be harmless by the time it reaches US shores.
“Observers on the west coast of the United States will be able to see a measurable increase in radioactive material three years after the event,” study author Dr. Erik van Sebille of the Climate Change Research Centre at the University of New South Wales said in a statement.
“However, people on those coastlines should not be concerned as the concentration of radioactive material quickly drops below World Health Organization (WHO) safety levels as soon as it leaves Japanese waters,” he added.
Some degree of atmospheric radiation was detected on the west coast of the US just days following the accident at the Japanese power plant, but Dr. van Sebille’s team explains the actual radioactive particles in the ocean plume take far more time to travel the same distance.
In the study, the authors used a series of ocean simulations in order to track the path of the radiation. The models identified it would most likely spend the better part of the next decade travelling through the world’s oceans.
A pair of energetic currents off the Japanese coast (the Kuroshio Current and the Kurushio Extension) has played a key role in diluting the radioactive material. Thanks to those currents, the radioactivity was considerably below WHO safety levels in under four months time, and the dilution process continued since then because of eddies, giant whirlpools, and other currents in the open ocean.
“Although some uncertainties remain around the total amount released and the likely concentrations that would be observed, we have shown unambiguously that the contact with the north-west American coasts will not be identical everywhere,” explained Dr. Vincent Rossi of the Institute for Cross-Disciplinary Physics and Complex Systems (IFISC).
“Shelf waters north of 45°N will experience higher concentrations during a shorter period, when compared to the Californian coast,” he added. “This late but prolonged exposure is due to the three-dimensional pathways of the plume. The plume will be forced down deeper into the ocean toward the subtropics before rising up again along the southern Californian shelf.”
According to the investigative team, the majority of the radioactive material will remain in the North Pacific, with only minute amounts crossing south of the Equator during the first 10 years. However, a measurable yet harmless signature of the radiation will spread into the Indian and South Pacific oceans over the course of several decades.
“Australia and other countries in the Southern Hemisphere will see little if any radioactive material in their coastal waters and certainly not at levels to cause concern,” Dr. van Sebille said.
He added the researchers had developed a website to help people keep track of the path of the radiation. “Using this website,” Dr. van Sebille said, “members of the public can click on an area in the ocean and track the movement of the radiation or any other form of pollution on the ocean surface over the next 10 years.”