If there’s been a saving grace in Japan’s nuclear crisis to date, it’s been the weather. With the exception of recent precipitation pulling some radioactive material down to the ground near the Fukushima Daichi plant, offshore breezes have been pushing most of the radioactive material out to sea. That could be a lifesaver (literally) for the residents of northeastern Japan. But what does it mean for the billions of creatures who inhabit the Pacific Ocean?
To answer that question, I got in touch with Dr. Ken Buesseler, a scientist at Woods Hole Oceanographic Institution who has actually used radioactivity from Chernobyl and nuclear testing in his research tracking chemical processes in the ocean. I asked him if we have a handle on what the situation in the western Pacific is right now in terms of types and levels of radioactive material. Short answer: NO.
We have no data on fallout to the Pacific Ocean, other than they have said that releases include Iodine-131 and Cesium-137… Iodine-131 has a short half-life (8 days) and is gone in a month but is of more immediate exposure concern due to its uptake in the thyroid particularly by young children. Cesium-137 has a longer 30 year half life, so that will still be around after decades.
Where in the world – and ocean – radioactive material from Japan will end up depends largely on wind and weather conditions. As Jeff Masters explained recently on Wunderblog, the high pressure system that has been driving the offshore winds has also likely kept radioactive material close to the ocean’s surface, increasing the chances that much of the material will be deposited into the Pacific rather than whisked around the world on the air currents higher in the atmosphere. (Obviously, I’m not saying it’s all just falling into the ocean and not going anywhere. There are reports today that radioactive material from Japan has reached the west coast, although not at levels harmful to humans.)
Still, Buesseler points out that doesn’t necessarily spell disaster for marine life in the Pacific Ocean.
It’s also important to remember that there are many sources of radioactivity, both man-made (atmospheric weapons testing in 50′s/60′s, Chernobyl in 1986), and natural radionuclides (uranium, radium, radon, etc). We studied fallout Cesium-137 from Chernobyl in the Black Sea and could see an increase in surface waters that was 10-20 times the prior levels (that’s higher than weapons testing fallout). Even at these higher levels, the ocean was safe for bathing, seafood consumption, etc.
ScienceInsider’s Sara Reardon explains that’s because the amount of radioactive material pales in comparison to the vast quantity of water and non-radioactive salts that make up the ocean:
Effects on marine life should be minimal if the plume is blown over the ocean. Radioactive isotopes are most dangerous when animals’ bodies absorb them, thinking they’re something else. For instance, cesium-137 mimics potassium and is absorbed by muscles, while strontium-90 mimics calcium and is taken up by bones. Since ocean water is full of potassium and calcium in the form of salts, this lowers the chance of an animal’s body taking up radioactive particles by mistake.
Furthermore, since the Pacific is so massive, radioactivity will be diluted to levels far too low to be toxic to aquatic life. A much bigger concern is the plume blowing over land and contaminating plant life or the freshwater supply, which would affect animals (including humans) further up the food chain.