Senior scientist Ken O. Buesseler at Woods Hole Oceanographic Institution was early on the scene off the coast of Japan measuring radioactive contaminants released into the ocean from the Fukushima nuclear power plant accident after a powerful earthquake and resulting tsunami hit the area, March 11, 2011.
“It was an alphabet soup of radioactive contaminants,” Dr. Buesseler said. “There was concern because the release we started to see was tremendously high.”
Dr. Buesseler, who early in his career studied the spread of radioactivity in the Black Sea after Chernobyl, described the disaster site as a crime scene in that it was important to get there as soon as possible to take measurements. He received funding within weeks from the Gordon and Betty Moore Foundation to travel to Japan and start sampling.
Now, almost exactly five years later, he continues to monitor the legacy of the triple disaster, radioactive contaminants released into the ocean, in collaboration with Japanese scientists. Data show that small amounts of radionuclides continue to leak from the Fukushima site and traces have traveled 5,000 miles across the ocean to the western United States and Canada.
Specifically, Dr. Buesseler tracks levels of Cesium 137 and 134. These radioactive cesium isotopes were most abundant in the water after the accident. For example there was 40 times more cesium than another isotope monitored, Strontium 90.
Radioactivity in the water is measured by becquerels per cubic meter of seawater (Bq/m3). Before the disaster the number for cesium levels was 2 off the coast of Japan, the peak after the accident was 50 million, and recently higher measurements have reached 200.
“If the source stopped we would expect to see 2 (Bq/m3) in fact we still see numbers as high as 200,” Dr. Buesseler said.
One thousand tanks full of radioactive waste remain at the site which scientists suspect are leaking waste into the ground water and ocean, especially after heavy rains.
However, Dr. Buesseler said that these levels are not high enough to pose a human health risk. For example, they are thousands of times lower than in 2011 after the accident and well below the limits for drinking water which is 7,400 Bq/m3.
Dr. Buesseler said that man-made radioactive contaminants were found in nature before Fukushima, released from atomic testing in the 1960s and Chernobyl. These sites continue to be a small source of contaminants released in the environment. However, what made Fukishima different is that such a high amount of contaminants were deposited into the ocean at once.
Scientists have also been testing for radioactivity in fish. Fisheries off the coast of Japan were closed for a period of time when levels were high, but they have since been reopened Dr. Buesseler said.
A few years after the disaster Dr. Buesseler expanded his monitoring program to the West Coast after he began receiving calls about if and when radioactive contaminants from Fukushima would reach the West Coast after people began observing wreckage from Japan.
“It was a very visual sign showing what happened in Japan could reach our coast,” Dr. Buesseler said.
However, finding funding posed a challenge.
US government programs and funding for radioactive contaminant studies had ended in the 1980s after Chernobyl.
“People thought this would never happen again,” Dr. Buesseler said.
He turned to crowdsourcing to fund testing of samples collected by volunteer citizen scientists on the West Coast under the organization Our Radioactive Ocean which Dr. Buesseler started.
The highest levels of cesium measured on the West Coast are 6 to 10 Bq/m3, which do not pose a public health threat.
“If you swam every day for a year with these levels, exposure would be 1000 times smaller than a single dental x-ray.” Dr. Buesseler said.
So far the organization has collected 250 samples from between San Diego to Alaska and to Hawaii. Four hundred and forty individuals and 10 organizations have funded testing the samples, which each cost about 500 to 600 dollars to test.
“It’s become a really good tool to educate people,” Dr. Buesseler said. “I consider it a public education campaign as much as a scientific study.”
Understanding how radioactive contaminants travel through the environment is a skill that should not be lost while the world continues to use nuclear power.
“We need to train the next generation,” he said. “I am going to retire at some point, and I can’t put a student on a project because there is no funding.”