[morelisp]

The actual data:

> That water will contain about 190 becquerels of tritium per litre, below the World Health Organisation drinking water limit of 10,000 becquerels per litre, according to Tepco.

Google tells me regular seawater is 14 Bq/l.

Anyone with physics knowledge want to do the journalist's actual job and chime in? 10x worse than average sounds bad but 50x better than safe sounds good. What's the actual effect here? Is the tritium itself the problem (vs. I'm assuming, usually potassium)?

[x86x87]

It's a mixed bag.

https://www.nrc.gov/docs/ML1029/ML102990104.pdf

Who is 10000, but this varies with EU having a 100 bq/l limit, US a 740 limit, Canada 7000/l

So going by WHO recommendation it's fine, but 2x what the limit in Europe is.

Looks like normal levels are 5-15 /l depending where it's measured.

So: this is probably 10x what you'd encounter naturally but allegedly way under the limit depending on who is making the recommendations (with EU somewhat of an outlier)

[djmips]

But the ocean is vast. So wouldn't this mix in and ultimately be an imperceptible change in the average?

[x86x87]

In theory yes. In the real world I would not be surprised to hear that there are higher concentrations in specific areas due to currents and whatnot (ie it would take a while to evenly spread out)

[galleywest200]

Maybe globally and eventually, but at first the nearby nations could possibly have elevated levels in their surrounding waters for the time being.

[mentalpiracy]

I wanted to math this out.

East china sea: ~770,000 square km surface area; 350m average depth = 269,500,000,000 cubic meters of water

First discharge = 7,800 cubic meters over 17 days == approx. 459m^3 released / day == 1.70315399 x 10^-9

They might find five or six extra tritium atoms per liter of water.

Does this one off make it okay to dump into the ocean generally? No obviously not, the ocean is not just a magic dumpster to make bad things disappear. But in this case, tritium already exists naturally in sea water, and the introduced concentration has already been minimized.

If your personal heuristics for avoiding risk push you towards avoiding Japanese seafood over this, that's fine, but you should actually be avoiding all seafood.

[morelisp]

My intuition could be way off, but I think there's more than 10x more water (even at some ridiculously thin surface depth) between Korea and Japan than there is in the Fukushima tanks.

Wikipedia says 210 km³ flows into the Sea of Japan yearly. The article says the total stored water is "one million metric tons", which is... probably within the measurement error of the total SoJ flow.