There is a new study out with strontium-90 (and strontium-89) levels measured in the Pacific ocean. (It is available here in pdf form.) These measurements were taken in May-June 2011. They found that most of the Sr-90 came from direct discharge into the ocean at that time, rather than by atmospheric deposition.
They found that the amount of Sr-90 came to 2.65% to that of cesium-137. They remarked that Tepco found that this ratio was 0.01% Sr-90 to Cs-137 in topsoil (Tepco is lying, of course). But then they said that there was an accidental discharge of Sr-90 into the ocean in December 2011, and these results only apply to the time before that.
MEXT published a study of strontium and cesium in seawater for the period Oct. 24 – Nov. 9, 2012. There are 5 measurements which contain both Sr-90 and Cs-137. The average ratio here is 44%. This is much higher than the 2.65% found in June 2011.
Tepco has been attempting to purify contaminated water. The decontamination system does not remove Sr-90. Guess where it’s going? Also, strontium volatilizes at 1400 degrees C, and the underground coriums and spent fuel pools may have risen to this temperature since the initial melt-throughs, due to criticalities or cooling system failures. Tepco is planning to dump contaminated groundwater into the ocean, so plan on seeing this rise still further.
Also, the authors found strontium-89 levels to be no more than 4.3 times those of Sr-90. But Dr. Saji estimated that the inventory of Sr-89 was 15 times that of Sr-90. Something is not right. Sr-89 is a highly energetic radioisotope with a half-life of 50 days. It is more dangerous in the short term than Sr-90, and typically there is much more of it. The Sr-89 from the initial meltdowns has decayed, but the damage has already been done to our bone marrow, and its ability to produce T-cells to fight infections and regulate our immune systems. Inflammation, leukemia, bone cancer, and autoimmune diseases like atherosclerosis may result.