4
$\begingroup$

I have made a few chemosynthetic and photosynthetic organisms as bases of the food chain for my worldbuilding project, and I thought why not make a radiosynthetic one?

Radon forms from the decay of radium-226, which is one of the products in the decay chain uranium and thorium, and since those chemicals aren't going anywhere for a long time, in certain localized areas (like the ocean floor), radiosynthetic organisms might be able to thrive. I understand that these organisms wouldn't probably be everywhere, but they could be present in certain localized systems.

Radon releases alpha particles, which are safer (and less-energetic) than most other types of radiation, so less cell-shielding to protect against cell damage and potential mutations would be needed. I also understand that there are certain fungi that use this on earth (except with hard gamma rays).

I've got an idea for a fungi or microorganism that collects these alpha particles and uses them to power chemo or photosynthetic reactions on my world. I just have one question: would the alpha particles serve as an energetic-enough source to power chemo or photosynthetic reactions in a relatively radon-enriched environment (in some places as it doesn't need to be the base of the entire food chain)?

Thanks in advance.

$\endgroup$
6
  • 1
    $\begingroup$ I think radiation is a bad basic energy source for life. Especially from something like radon which decays in a matter of days. So unless you can somehow get a lot of nuclear fusion going going life will never develop to begin with. If want an alternate energy for your live just go with geothermal energy or anything other than radiation. $\endgroup$ Mar 24 at 20:02
  • $\begingroup$ This is not meant to an insult nor may i be 100% correct about my assumptions. But from what i know radiation ain't going to cut it. $\endgroup$ Mar 24 at 20:03
  • 2
    $\begingroup$ I know. I just wanted to know if it is possible and i am already using chemosynthesis and photosynthesis. It just sounds like an interesting idea to implement. $\endgroup$
    – Neil Iyer
    Mar 24 at 20:04
  • $\begingroup$ I mean maybe at a small scale with something like mirco organisms and nuclear materials that don't decay in a few days. But i am not an biologist so i can't really say for certain. $\endgroup$ Mar 24 at 20:06
  • 2
    $\begingroup$ True and that is what I'm trying to get at. This is not supposed to be the base of my food chain, just some sort of interesting biochemistry that you might find once in a while. $\endgroup$
    – Neil Iyer
    Mar 24 at 20:07

3 Answers 3

2
$\begingroup$

TL;DR: unlikely. There's probably not enough radiation, and you have to be basically on top of the radiation source in order to harvest alpha particles instead of having them be absorbed by the environment around you.


alpha particles, which are safer (and less-energetic) than most other types of radiation

They are less penetrating than other flavors of radiation, and that makes them safer to things like humans who are wrapped in a layer of dead cells that absorbs alpha particles quite effectively before they can reach the living, vulnerable meat underneath. If alpha emitters can get past the inert defenses and into the soft, vulnerable insides then they can wreak havoc... eating or inhaling such materials is bad news. That's why radon is such a problem for humans, because it is a nice, heavy, naturally occurring gas-phase alpha-emitter that concentrates well in places without adequate ventilation. Have a look at the notion of "quality factors" when computing effective radiation doses. The wikipedia page for the Sievert gives a weighing twenty times higher for alpha particles than gamma rays!

Unicellular things, or colonies of unicellular things don't really have protective layers that are many cells thick, and as such alpha radiation is quite hazardous to them... potentially more so than the gamma radiation that the radiotrophic fungi in chernobyl apparently use.

The next issue is now you actually get that tasty alpha particle. A 5.6 MeV alpha only travels about 4cm in dry air, and more like 4 micrometers in water. Those gammatrophs can just stick to walls and wait patiently for the gamma rays to come to them because mere air or even a little bit of concrete won't block much, but your alphatrophs can only consume what they're directly on top of.

The decay of one mole of radon-222, assuming an average kinetic energy of the emitted alpha particle of 5.5 MeV, would generate quite a bit of energy... over the first half life of three and a bit days, the average energy release would be on the order of hundreds of kilowatts. Thing is though, its hard to generate that much radon! Give one mole of radium-226, you'll generate half a mole of radon-222 in 1600 years which gives a yield more like 5 watts. And that's 5 watts of pure kinetic energy, and in practise the harvesting process is probably only a few percent efficient at best, which knocks another order of magnitude or two off the figures.

Of course, fine pure radium dust isn't something you'll find very often in nature. There's quite a bit of work done on radon emission, unsurprisingly... eg. Radiation From Granite Countertops Information Sheet from the Health Physics Society. They suggest A nice slab of granite will be producing less than 5 Bq of activity (eg. 5 radon nuclie decaying per second) which gives a less than impressive 3.7 picowatts of kinetic energy. You need many, many orders of magnitude higher concentrations of radionuclides to feed your fungus. I'm not sure your fungi could grow anywhere outside of a dumping ground of unencapsulated nuclear waste, or perhaps something like the "blue smokers" in Stross' Neptune's Children which posits natural uranium fission in deep sea hydrothermal vents on young worlds.

$\endgroup$
2
$\begingroup$

Radon releases alpha particles, which are safer (and less energetic) than most other types of radiation, so less cell shielding to protect against cell damage and potential mutations would be needed

Suggesting that radon's alpha particles are safer and less energetic than most other types of radiation, and therefore require less cellular shielding, can be misleading. In reality, alpha particles are highly energetic, with energies between $5$ to $10$ MeV. Beta particles (which can be electrons or positrons) have energies typically less than $1$ MeV, but this represents a broad energy distribution with some beta particles exceeding this range. Gamma rays, commonly have energies around $1$ MeV, however, they can reach several MeVs of energy depending on the nuclear transition involved.

Moreover, alpha particles have a charge of $+2e$ while beta particles have a charge of $\pm 1e$. Alpha particles are the most dangerous once they enter the cell. They act like a wrecking ball, breaking molecules, DNA, chemical bonds, etc.

So, I want to say no, they can't serve as an energy source as they are too powerful. In fact, they are sometimes used in radioactive decay energy sources for spacecraft power systems, known as radioisotope thermoelectric generators (RTGs). To clarify, they are not directly used in engines, they just provide electricity to the spacecraft.

$\endgroup$
2
$\begingroup$

There is a bacterium that lives off radioactive energy. It was discovered in 2008 in samples of 60C groundwater from 3 Km underground in the Mponeng gold mine in South Africa, where it has lived for millions of years apart from any other life form. It does not use the radiation directly, but uses the chemical byproducts of the free radicals generated by the radiation from Uranium decay.

So, things can live off the products of radioactive decay. However, I am not sure the bacterium would use it if it had anything else to eat. It has only managed it because it was the only lifeform in its ecosystem. There isn't really a 'food chain' as such.

$\endgroup$
1
  • 1
    $\begingroup$ I am going to use an analogue of this bacterium. After uranium and thorium break down ground-ammonia into amino radicals, the bacterium combines two amino radicals into hydrazine, creating energy. $\endgroup$
    – Neil Iyer
    Mar 26 at 19:26

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .