Thread: Deep in the earth

Is it possible that deep say 20km into the earth there is stuff we don't know about, undiscovered elements, life etc???

Yes.

Suff we don't know about, yes. Undiscovered elements, no. A new element would have to have a different number of protons than the ones already discovered, and they've all been discovered up to at least element 111 and a few higher. The heavier elements are unstable. Physicists generally look for new elements by smashing smaller atoms together. There's nothing deep in the earth that would make them more stable.

As far as life is concerned, I doubt it. The deepest hole ever drilled was 12.2 kilometers. The temperature at this depth was 180°C (356°F).

Originally Posted by rjc79

Is it possible that deep say 20km into the earth there is stuff we don't know about, undiscovered elements, life etc???

Some literature suggests that extremophiles exist quite deep into the Earth's crust where temperatures are very hot. It's certainly likely that there are forms of bacteria we have never seen before. Complex, multicellular life at those depths? Extremely UNlikely.

As mentioned, it's not likely that never before seen elements exist within the Earth, but it's very likely that exotic minerals formed under high pressures and temperatures exist that scientists don't know about.

Minerals and other things we haven't seen I'd believe.

Not so sure about life, 20km is really deep and hot.

Yes, life v. deep.

There are strong indications that microbial life is widespread at depth in the crust of the Earth, just as such life has been identified in numerous ocean vents. This life is not dependent on solar energy and photosynthesis for its primary energy supply, and it is essentially independent of the surface circumstances. Its energy supply comes from chemical sources, due to fluids that migrate upward from deeper levels in the Earth. In mass and volume it may be comparable with all surface life. Such microbial life may account for the presence of biological molecules in all carbonaceous materials in the outer crust, and the inference that these materials must have derived from biological deposits accumulated at the surface is therefore not necessarily valid. Subsurface life may be widespread among the planetary bodies of our solar system, since many of them have equally suitable conditions below, while having totally inhospitable surfaces. One may even speculate that such life may be widely disseminated in the universe, since planetary type bodies with similar subsurface conditions may be common as solitary objects in space, as well as in other solar-type systems.

http://www.pnas.org/content/89/13/6045.short

See here:

http://www.astrobio.net/news/modules...rder=0&thold=0

for a good current summary. AFAIK we have yet to drill to a point wherein no life is found, ie have yet to find a sterile depth.

Originally Posted by free radical

AFAIK we have yet to drill to a point wherein no life is found, ie have yet to find a sterile depth.

According to this article the deepest life found was at 3 miles.

Scientists have found the most extreme single-celled Archaea yet, subsisting on methane nearly three miles below the surface

But the deepest hole drilled was almost 8 miles.

http://en.wikipedia.org/wiki/Kola_Superdeep_Borehole

Cheers,

Any research in that borehole looking for biomarkers?

similar to what you were saying,

Recently, living cells - many of which are Archaea from the Pyrococcus and Thermococcus genera - were found in a mud core taken from 1.6 km below the sea floor off the coast of Newfoundland. Though they represent the deepest life ever discovered beneath the sea floor, microbes of various kinds have been discovered at even greater depths under the continents. Communities of microorganisms have been found hunkered down in groundwater as far as 5 km below the surface of the land. Scientists think life exists even further down - to the point where the subsurface heat becomes unbearable for life.

Not sure what temperature that would be as there is a concurrent increase in pressure.

Any event, I remain unaware of depth being prohibitive to microbial life.

Hmmm so that answers another question.

If you could dig a holl deep enough, hot air rises, at 180 degrees, that could heat water, which is no different to current forms of power. Get on your skates governments.

do you realise how long the russians had to drill to get to that depth ?

Geothermal is a viable source of energy but more practical where the earth's heat is closer to the surface. It has its own set of problems, but at least it doesn't depend on the weather like wind and solar do.

on the other hand, ground source heat pumps are relatively inexpensive, and in principle available in most places

Originally Posted by Harold14370

Geothermal is a viable source of energy but more practical where the earth's heat is closer to the surface. It has its own set of problems, but at least it doesn't depend on the weather like wind and solar do.

My bold.

The basin and range province of the western and south-western US would be an ideal location.

Originally Posted by free radical

Scientists think life exists even further down - to the point where the subsurface heat becomes unbearable for life.

Not sure what temperature that would be as there is a concurrent increase in pressure.

Is there a temperature at which proteins break down? Would that represent some sort of upper limit to the possibility of life?

Yes but the point is that the increased pressure might raise the limit on what temperature is too hot.

Proteins denature from heat because of reduced hydrogen bonding. But proteins from some organisms that evolved under hot conditions can exist in near-boiling conditions (see Thermus aquaticus and others)

The theoretical temperature limit should be different under low and high pressure.

I'm surprised that chemical bonds, which are electrical, would be affected by pressure independently of temperature (if that's what you are saying).

(I should clarify: I know that chemical reactions are affected by pressure, due to there being more entities per unit volume and a greater likelihood of a collision. However, is an already-made bond more or less likely to rupture just because of pressure?)

I may be confused. Boiling occurs at a higher temperature under pressure. I believe there is some impact on protein structure as well.

Some species and proteins are suited to high pressure (barophiles) and others are suited to high temperature (thermophiles) and without giving it a tremendous deal of thought it seems that a protein's folding in response to heat under increased pressure would be different than that under atmospheric pressure.

Some microorganisms survive autoclave conditions, typically in a sporulated state or as a quasi-alive prion. That a spore or prion can survive 115C + 11psi indicates that biological molecules can under the right conditions be largely unaffected by a degree of heat and pressure once thought to be prohibitive to life.

I am unaware of any evidence that depth is prohibitive to life. thus far the depths that we have drilled and asked have to my knowledge yielded detectable biomarkers.

I may be more confused than you are and am approaching this from a chemical engineer's perspective, knowing next to nothing about biology. I think that in looking at how organisms survive at extreme conditions there should be a distinction between physical and chemical limitations.

All I'm suggesting in response to your statement:

The theoretical temperature limit should be different under low and high pressure.

is that the chemical breakdown of proteins ought to be a strictly temperature dependent phenomenon. The chemical bonds are not going to be damaged in any way by extreme pressure if the temperature is not also extreme. There are barophiles that live in the sea under tremendous pressure at very cold temperatures.

Perhaps we are both confused.

The inactivation of proteins by heat is due to reduced hydrogen bonding and a disruption of tertiary structure. Water boils when hydrogen bonding is sufficiently reduced, in my understanding. If pressure increases the boiling point of water by promoting hydrogen bonding (?), then the hydrogen bonds that dictate the tertiary structure of proteins should be similarly promoted by increased pressure, at least perhaps.

If someone else reading this is less confused they may be able to shed a little clarity.

The barophiles decribed to date are psychrophilic, but that may be entirely due to sampling bias.

Originally Posted by Bunbury

The chemical bonds are not going to be damaged in any way by extreme pressure if the temperature is not also extreme.

I agree with this, but was initially saying only that the effect of temperature might be different in a pressurised environment, nothing about the effect of pressure whilst holding temperature constant.

Originally Posted by free radical

The inactivation of proteins by heat is due to reduced hydrogen bonding and a disruption of tertiary structure. Water boils when hydrogen bonding is sufficiently reduced

I think the hydrogen bonds among water molecules are considered physical bonds (not chemical). Is this also true of the hydrogen bonds within protein molecules? Is there a real difference in kind? I am asking because (obviously) I don't know the answer, and this seems to be somewhat important background information for a discussion of extremophiles.

Isn't everything physical in the final analysis? There is no chemical.

Any road, this is true for biological molecules, as I understand it. Consider base pairing in DNA. A G:C base pair has three hydrogen bonds; an A:T base pair has only two. Thermophiles have a higher GC content as a result. The GC content of E. coli = 51%, of Thermus aquaticus = 68%.

Hydrogen bonding is considered the main determinant of secondary, tertiary and quaternary structure of proteins, although cysteine bridges (a covalent disulphide bond) also contributes to tertiary and quaternary structure, if memory serves.

This link looks reasonable.

http://www.massey.ac.nz/~wwbioch/Pro...ds/framset.htm

Originally Posted by free radical

Isn't everything physical in the final analysis? There is no chemical.

Aye lad, but you've got me flummoxed. If you're mashing tea and you turn off the stove under the kettle the steam turns right back to water. If, on t'other 'and you boil an egg, when you turn off the stove it's still a boiled egg.

The boiled egg has congealed, individual proteins have crosslinked one t'other.

Originally Posted by free radical

The boiled egg has congealed, individual proteins have crosslinked one t'other.

So it's irreversible, and so is the denaturing of cells by heat, whereas the hydrogen disbonding that occurs when water boils is reversible. The processes are not comparable is all I'm suggesting, and if you boil an egg in a pressure cooker it's still irreversible and the steam still condenses back to liquid.

Something like that.