Oxidizing/Reducing Environments

[OSHMUNNIES]

Geologically/Ecologically speaking, what types of environments will produce oxidizing conditions, and similarly, which ones will tend to produce reducing conditions? (I understand the chemistry, so I don't need a lecture on redox reactions, I'm just a little naive as to how they are generated on a larger scale)

[CaptainPanic]

I think it's just dependent on that kind of elements are present on your planet?

 

There are theories about the formation of our solar system, and about the formation of solar systems in general.

[Mr Skeptic]

Uh, largely the presence of oxygen produces oxidizing conditions. In certain situations, microbial decomposition of organic matter will use up all available oxygen. Think stagnant water, for example.

[foodchain]

Geologically/Ecologically speaking, what types of environments will produce oxidizing conditions, and similarly, which ones will tend to produce reducing conditions? (I understand the chemistry, so I don't need a lecture on redox reactions, I'm just a little naive as to how they are generated on a larger scale)

 

Can you have one without the other?

[Alvinsolar]

Hi,

Nice article..

 

Upon exposure to oxidizing conditions and in the absence of alkaline materials, some sulfide minerals are oxidized in the presence of water and oxygen to form highly acidic, sulfate-rich drainage.

[skyhook]

I thought about a few examples...

High up in the atmosphere, there is ozone, O3 and it is said to be able to "scrub" some chemicals in the atmosphere. so I think with the extra oxygen it could be oxidizing.

For iron smelting, iron ores is heated to very high temperatures, and with coke or a carbon source. and after some processes, pure iron is obtained. I just read that carbon monoxide is a reducing agent. In nature, I guess volcano vents have high temperatures. and under the right circumstances, some stuff might get reduced.

and there are peat swamps in some countries. Some bodies are found buried in them in relatively good conditions, but they are ancient. However, I don't know if it is considered reducing environment, as the body is still rotting but very slow. and also I've heard of salt lakes but never been to one. salt being a preservative, maybe it has some effects on oxidation.

[Vulgaris]

Consider the ocean bottom sediments. Where there is organic material freely available, you will have microbes eating it. This happens to a large extent on the ocean bottoms, and especially near shore where the organic matter deposition is greatest. When microorganisms have eaten all the oxygen in the sediment, they continue with eating nitrate (if there is any), then oxidized iron, manganese, sulphate and so on and so forth. In the end there won't be many compounds left to use as oxidizers and you are left with doing fermentation, which doesn't require an external electron acceptor. but even long before that, these sediments are highly reduced, although the sediment surface is still oxidized - atleast the top few millimetres. In iron rich sediments you can see that the sediment is reduced if you scrape it with a finger and its all black below the surface. This is a result of iron sulphide accumulating as the hydrogen sulphide produced by sulfate reduction reacts spontaneously with the iron oxides in the sediments. In fact, these highly active, reduced systems are very important for cycling of all sorts of nutrients in the oceans. Read up on biogeochemistry if you'r interested in more along these lines.

 

/vulg