From the paper's estimate of the concentration in soil (43ng mercury per gram of soil) this mercury is dispersed in 18 exagrams of soil.
For scale, the concentration of mercury in permafrost is about an order of magnitude less than what is found in tuna, and about the same as what is found in haddock or mackerel. (At least according to Wikipedia: https://en.m.wikipedia.org/wiki/Mercury_in_fish)
Well from the one part is sounds like the concentration is normal:
>> Schuster and his colleagues found their measurements were consistent with published data on mercury in non-permafrost and permafrost soils from thousands of other sites worldwide.
Once you realize that, the whole thing becomes a big alarmist scare. If the arctic melts that doesn't mean the mercury is going to suddenly migrate into the rest of the world. It will probably be taken up in arctic plants and wildlife in the same proportions it exists everywhere else. But they seem to want us to think this is some new lurking scary demon of climate change that's going to come get us.
I was hoping to read something interesting, like a hypothesis about why mercury was concentrated in the arctic but all I got was a finding that it's the same as everywhere else.
I am curious if you are an expert in this field and know this to be true, or if you are making a quick assumption from a layman's understanding.
Reading the full text: http://onlinelibrary.wiley.com/doi/10.1002/2017GL075571/full Where there is more context to the quote about their measurements being consistent with non permafrost sites, and the discussion about active layer vs permafrost layers and mercury cycles, it is not clear to me that you take is correct.
It would be wonderful if someone knowledgeable could chime in.
I was just going mainly on that one paragraph which seems rather benign. It would be really nice to understand why they think it's not.
That 30-50ng/g is the concentration in uncontaminated temperate soil.
Could an order of magnitude less actually be a lot if you look at it that way? Since the permafrost would just be passively accumulating, as opposed to actively in a way which only something living can do.
Yes. This is called biomagnification. Basically, animals absorb heavy metals that are in the food they eat, but don't have an efficient way of excreting it again. Mainly since these metals are bound so they're fat soluble, not water soluble. The higher up in the food chain, the worse it gets.
Anyway, it says the median is 43±30ng/g, the mean 62±35ng/g. Why wouldn't they use the mean in the main results? That's what I imagine would give the 'concentration of mercury', the average (mean) concentration.
Reading the method, it's a huge guesstimate in a dozen ways, even much further than I would have thought. Guess that's how they get 13-73ng/g. I wonder how they have any confidence in the error range.
You just need the density of permafrost and then you can compute the volume from the exagram value, and depending on how thick you make it you get back either the surface of northern Canada and Siberia or you get a really really tall tower of permafrost that reaches into low earth orbit :-).
> I wonder how they have any confidence in the error range.
It is my understanding that there are many many core samples at various locations in the permafrost to understand its nature and make up. My guess would be that they derive the error ranges using the change in concentrations between all of the sample points leading them to a median and mean difference in concentration samples as their base set.
> "Please don't comment about the voting on comments. It never does any good, and it makes boring reading."
https://news.ycombinator.com/newsguidelines.html
It's best to just roll with it, I think. Follow the guidelines and post as substantively as you can. The population of HN is large and diverse and you're unlikely to be able to figure out why each and every downvote (or upvote, for that matter) is handed out, and even if you could, you may not agree with why they did so or think it’s fair. They can be useful as a guide and an opportunity to imagine how the comment may come across differently than you intend. But at the end of the day, it's the nature of the beast. Use what you find useful and let the rest slide.