What Fukushima accident did to the ocean

(CNN) -- One year ago, a series of events began with an earthquake off the cost of Japan that culminated in the largest accidental release of radioactivity into the ocean in history.

We have to be careful and say "accidental" because in the late 1950s and early 1960s, 50 to 100 times more radioactivity was released worldwide as fallout from the intentional testing of nuclear weapons. The word "ocean" is also important, since Chernobyl in 1986 was hundreds of miles inland, so it had a smaller impact on the concentrations of radionuclides in the sea than was measured directly off Japan in 2011.

One year later, we have to ask, what do we know about Fukushima's impact on the ocean and levels of radioactive contaminants in water and fish?

In many ways we were fortunate that impacts were largely confined to the ocean. Certainly, the Japanese people continue to feel devastating effects of so large a release within their country, and many people may never be able to return to their homes. But in general the winds during the height of the accident at the Fukushima Daiichi nuclear power plant were blowing offshore. As a result, more than three-quarters of the radioactivity fell on the ocean. This is important, as any that lands on soil remains in place, resulting in the potential for greater human exposure and increased chances of contamination to food supplies and property. Read More