Here's the paper behind that: http://iopscience.iop.org/1748-9326/7/3/034004/article http://iopscience.iop.org/1748-9326/7/3/034004/article Lest the logarithm

Here's the paper behind that: http://iopscience.iop.org/1748-9326/7/3/034004/article http://iopscience.iop.org/1748-9326/7/3/034004/article Lest the logarithmic scale confuse anyone, the concentrations over most of the ocean are tiny. The scale has a 5 order-of-magnitude range. As a reference point, Cs-137 background from atmospheric testing is a median 3 Bq/m^3 [1] in the Pacific. (Total weapons fallout was 25 MCi = 925 PBq of Cs-137 [2], about 30x Fukushima's 36 PBq [3]). Both are dwarfed by natural radioactivity, which includes 11 kBq/m^3 of K-40 [4]. [1] http://www.ncbi.nlm.nih.gov/pubmed/15245845 http://www.ncbi.nlm.nih.gov/pubmed/15245845 [2] http://books.google.com/books?id=JLFX6EMPqBkC&pg=PA34 http://books.google.com/books?id=JLFX6EMPqBkC&pg=PA34 [3] http://www.pnas.org/content/109/16/5984.full http://www.pnas.org/content/109/16/5984.full [4] http://www.physics.isu.edu/radinf/natural.htm http://www.physics.isu.edu/radinf/natural.htm