Thursday, October 15, 2009

Oxygen: Saviour

We're the blue planet. That's us. When you're talking planets - blue is associated with life. The blue colour comes from oxygen which makes up a large portion of the weight of a water molecule. And the blue sky also comes from the element oxygen. Oxygen comprises twenty-one percent of our atmosphere.

The colour red also has to do with oxygen. Rust, gets it's red colour because it is oxidized iron. Blood gets it's red colour from the iron and oxygen in hemoglobin. The planet Mars gets it's red colour from oxidized minerals which means that Mars used to have oxygen, probably in the form of water.

Oxygen, with it's all consuming hunger for electrons, has a lot of potential energy. But it is potential for good or ill. Free oxygen has the potential to destroy biological molecules. That's why we use bleach to get out stains. Bleaching is an oxidation process. Oxygen, by grabbing electrons from other elements, weakens covalent bonds in organic molecules leading to their disintegration.

Atmospheric oxygen is the source for ozone, a molecule made up of three oxygen atoms. Ozone is a toxic pollutant, an ingredient in automobile exhaust, but it also exists in the atmosphere where it protects life on Earth from ultraviolet rays. High up in the atmosphere a layer of ozone absorbs the ultraviolet light that would otherwise harm living creatures.

Not only does ultraviolet light harm living things but for time periods of billions of years it has even greater potential for harm. The high energy content of ultraviolet light means that it has the power to break the bonds of water molecules.

Once liberated from water, hydrogen can escape Earth's gravity into space. Without protection, over billions of years, the sun's ultraviolet rays could deplete the oceans of water.

There is evidence on Mars – the famous “Canals” - that there was once water there. Now there is no water and only a thin atmosphere of carbon dioxide. No oxygen in the atmosphere. No ozone to protect against ultraviolet light. No water anymore. And without water there is no life.

No life without water and no water without life. Earth has both. Mars had only one and now has none.

Twenty years ago there was an international treaty signed to protect the ozone layer from a man-made substance called freon. Freon was used as the main coolant in virtually all refrigerators and air conditioners. The problem was that when it was released into the air , which is what happens eventually when all fridges and air conditioners are discarded, it rose high into the atmosphere where it chemically reacting with ozone - destroying it.

Sometime during the 1990's Scientists discovered a “hole” in the Ozone in the southern hemisphere. The Ozone hole has gotten smaller since countries complied with the treaty and stopped manufacturing freon, but not before it took it's toll on Australia, where the incidence of skin cancer has increased considerably.

When bacteria first existed there was no oxygen so there was no ozone to protect living things from ultraviolet rays. It took millions of years for oxygen to reach a high enough percentage for the protective ozone layer to develop. We call that a “Time-lag. In that time bacteria were on their own to develop resistance to these deadly toxins: oxygen and ultraviolet light.

Life is autopoietic, but in maintaining itself life alters the chemistry of the Earth. And when that chemistry changed from zero free oxygen to twenty-one percent free oxygen, life developed in a radical new direction.

From photosynthesis, to – “respiration” – the utilization of oxygen to supply chemical energy to life, oxygen,which was first a pollutant and a toxin, became the basis for all new forms of life.

Tune in next week when we learn who helped Oxygen turn from the “dark side” and transform into a Creator.

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