Amount of seawater on Earth: 1.338 billion km^3 (according to Wikipedia). Assuming 1.0 kg/L, this is 1.338 * 10^18 ton.
Seawater is about 0.04% potassium, so this is about 5.35 * 10^14 ton of potassium.
Potassium contains naturally occurring radioactive isotope (40K): the radioactivity of potassium is 31 Bq/g. Hence the natural radioactivity of all potassium in seawater is 1.66 * 10^22 Bq.
For comparison, again according to Wikipedia:
> In May 2012, TEPCO reported that at least 900 PBq had been released "into the atmosphere in March last year [2011] alone"
...which is 9 * 10^17 Bq, or about 1/18,000 of naturally occurring radioactivity in the ocean due to potassium alone.
(We didn't even start on stuff that are commonly considered "radioactive", like all the uranium and thorium lying beneath where you are.)
* Meanwhile we're busy burning fossil fuels, increasing the amount of CO2 in the atmosphere by ~30%.
Seawater is about 0.04% potassium, so this is about 5.35 * 10^14 ton of potassium.
Potassium contains naturally occurring radioactive isotope (40K): the radioactivity of potassium is 31 Bq/g. Hence the natural radioactivity of all potassium in seawater is 1.66 * 10^22 Bq.
For comparison, again according to Wikipedia:
> In May 2012, TEPCO reported that at least 900 PBq had been released "into the atmosphere in March last year [2011] alone"
...which is 9 * 10^17 Bq, or about 1/18,000 of naturally occurring radioactivity in the ocean due to potassium alone.
(We didn't even start on stuff that are commonly considered "radioactive", like all the uranium and thorium lying beneath where you are.)
* Meanwhile we're busy burning fossil fuels, increasing the amount of CO2 in the atmosphere by ~30%.