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Asked by Nicola to Colin, John, Kevin, Shikha, Triona on 7 Nov 2014.
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Shikha Sharma answered on 7 Nov 2014:
Hi Nicola,
Its a really good question. Let me try to answer it but I am sure you will get a complete answer after getting response from other scientists here. 🙂
So, as we know that the Earth’s atmosphere constitutes 77% nitrogen, 21% oxygen, with traces of argon, carbon dioxide and water. The oxygen levels are generally maintained by biological processes. On earth, there are few places known as dead zones or anoxic waters that are depleted or have a dissolved oxygen concentration of less than 0.5 milligrams per liter. Oxygen deficiency, also called as hypoxia, is caused by an interaction between biological, chemical and physical factors. Dead Zones occur around the world in both fresh and saltwater systems like Lake Erie, Oregon, Lower St. Lawrence Estuary, Chesapeake Bay, northern Gulf of Mexico, and the Baltic Sea. Dead zones are also formed due to excessive nutrient pollution from human activities united with some other reason.
So, in order to avoid the dead zones which are not natural we should avoid polluting water bodies.
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Kevin Motherway answered on 8 Nov 2014:
Yes the vast majority of the planet has little or no oxygen available for life and most life can do quite fine without it. In the early history of the planet oxygen was highly toxic and only a very small fraction of life could tolerate it. Some forms of life actually produced it as a byproduct (like trees still do) and so the amount of oxygen in the atmosphere grew to 20-ish %
The vast majority of bacteria thrive in anoxic (oxygen free) conditions just like the ones in your intestines and instead of using oxygen and producing CO2 as their respiration product they give off things like methane or hydrogen sulphide gas. If you have a wheelie bin full of yummy food for bacteria to munch on, in the first few days the aerobic bacteria munch the food in the presence of oxygen and generate CO2, but without new air getting in they use up all the oxygen and they suffocate and die and then it’s party time for the anaerobic bacteria who don’t need oxygen and they thrive and produce Methane and break any sulphides in the food down to Hydrogen Sulphide gas-that rotten egg smell gas we know so well. In many countries the compost bins actually have holes drilled in the sides to stop the bin going anoxic. Ironically if you keep your compost bin lid slightly open, it will be LESS smelly because you’re keeping the aerobic bacteria happy and you keep the most toxic of substances for anaerobic bacteria (oxygen) in plentiful supply, so they can’t generate their dastardly smells. However you’ll also let in the flies and vermin. It’s hard to win. This is the reason why if gardeners don’t turn compost heaps regularly to introduce new oxygen, the anaerobic bacteria thrive, cause smells and can even cause a methane fire.
All higher life like mammals have an oxygen based chemistry and without it you’ll start to die in only 4 minutes. So you can quite easily have simple life in the absence of oxygen as long as you have some water, so life on Mars is quite a possibility but it’s probably going to be bacteria or slime of some kind living in the pore of rocks with some liquid water but not necessarily oxygen.
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John Wenger answered on 10 Nov 2014:
As Shikha and Kevin mentioned, there are a few places where the amount of oxygen is very low.
There are some other (non-natural) places too….
Oxygen dissolves in water and because it is very reactive it can interfere with some chemical reactions we are trying to carry out in the lab. So we simply get rid of the oxygen by bubbling another gas (e.g. nitrogen) through the liquid to “displace” the oxygen.
Another place is a high vacuum chamber. Sometimes we need to do experiments with gases at very low pressures (high vacuum) so we have large pumps to reduce the amount of oxygen down to a billionth of the amount in air!
In fact The Large Hadron Collider is a very large vacuum chamber and probably one of the places with the lowest amount of oxygen on earth!John
Comments
Nicola commented on :
Thanks so much your answers were very helpful! 🙂