I am working on a planet that has insignificant (almost 0 degrees) tilt, no moon, rotates twice as fast as Earth.

I intend to create quite an exotic "biome", so to speak, in a subtropical desert zone which has toxic lakes of mercury. From what I understand, mercury evaporates rather slowly.

Is it possible, or even plausible, and if not, could it be any other toxic element? How large could they become? And furthermore, could there be life that adapted to such toxic environment?

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    $\begingroup$ Hm a lake of mercury, that would be a seriously heavy lake. $\endgroup$
    – Rob
    Commented May 2, 2019 at 22:02
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    $\begingroup$ Metallic mercury slowly oxidizes in nature. Your planet either needs to be less oxygenizing (to the point that human breathing is not possible), or has some geological process to supply fresh mercury. $\endgroup$
    – Alexander
    Commented May 2, 2019 at 22:09
  • $\begingroup$ Liquid mercury is not that poisonous. $\endgroup$
    – Willk
    Commented May 2, 2019 at 22:16
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    $\begingroup$ "Any other toxic element": All things are poison, and nothing is without poison, the dosage alone makes it so a thing is not a poison (Paracelsus). I'd say that the only definitely non-toxic elements are the noble gases. Furthermore, there are only two chemical elements which are liquid in standard conditions, namely mercury and bromine. Both are toxic. $\endgroup$
    – AlexP
    Commented May 2, 2019 at 22:41
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    $\begingroup$ @AlexP actually the big nobles are poison too. I had read that xenon was an anaesthetic. Here youtube.com/watch?v=rd5j8mG24H4 Cody breathes each noble gas. Krypton and xenon definitely mess with him and he struggled some to get the xenon out. $\endgroup$
    – Willk
    Commented May 2, 2019 at 23:26

1 Answer 1


Yes and no. you can make it work by having a hard ground: Mercury is heavy. 13 times denser than water, so I would put it into a not too deep, flat lake with some kind of solid rock bottom. More importantly: Mercury is very much not reactive, and it does not corrode. So have no worries about it corroding away. Another problem is that it will evaporate. Very slowly, but it will. Not enough to have clouds and rain but too much for it to stay forever.

a drop evaporates at 6ng/h, surface area of a drop is 50mm^2. chiemsee has 1,5x10^12 times the surface area and thus evaporation rate: 9480kg or almost 10 tons per hour. (22046.2 pounds). That is only 667 liters or or 3.2536585e-8% of the total volume, but on it will take only 3073463268.37 hours, 350851 years or 0.0077% of earths total life.

I am not saying it is impossible, but the fumes would kill you all around it. Maybe life around it will adapt? Who knows.

EDIT: Unless it is sourrounded by huge mountains, water will rain onto it, will float on top of it and cover it. There won't be any evaporation, since it is completly covered. But there will also be nothing to be seen.

EDIT2: I forgot to mention that if there are no winds it will not evaporate as fast, as the evaporated Mercury will not be carried away, which hinders the evaporation rate

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    $\begingroup$ Yes, it would be in a rain shadow of tall mountains. But 350 thousand years seems like a reasonable length, unless it would be replenished from beneath somehow. $\endgroup$ Commented May 3, 2019 at 21:58
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    $\begingroup$ @RavenInvazion Hey, my other account here (the other one is the one I use at work for stackoverflow). It came to me that 'mercury air' is also very heavy, so maybe it does not float away and stays above the lake like fog over regular lakes, maybe it rises not high enough to climb over the mountains and collects itself at some mountain slopes, feeding itself back with streams of mercury occasionally forming and flowing. Maybe both. Since you did not ask for 'hard science' I believe you can chose either and be good. $\endgroup$
    – Maritn Ge
    Commented May 3, 2019 at 23:33

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