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View Diary: Fukushima: CA Universities Launch Kelp Watch 2014 (20 comments)

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  •  Hi Joieau (0+ / 0-)

    Please see my reply to your comment.  The amount of Sr-90 an organism will incorporate depends on the concentration of Ca2+, Sr2+ and Sr-90 in seawater.  The first two are not changing and the 3rds concentration despite continued release will not unless release rates increase dramatically.

    Cs isotopes bioaccumulate to a greater degree than does Sr-90 in marine organisms by a factor of 5-30 (link). That means at the same concentration there will 5-50 times more Cs in organisms than Sr.  But the concentration of Cs-137 is much, much higher in the plume given that initial releases of Sr-90 were about 3% of Cs.  Now after the initial releases Japanese marine fish were showing ~10's of Bq/kg Cs isotopes averaging around 18 Bq/kg excluding the immediate vicinity near to the reactors.  Sr-90 would be much lower given the lower concentrations.  A fish with 18 Bq/kg Cs-137 if ingested by a person imparts a dose of about 60 nanoSv per kg consumed.  If you increase the exposure by a factor of 10 from other radionuclides you get to roughly half a microSv. How much do you think looking at Cs alone underestimates dose? An order of magnitude? Two or three? The dose from 210-Po alone is over 23,000 nSv kg consumed.

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