Our vital and finite resource

Our vital and finite resource

We seldom consciously think about how often we need clean water. Where did it come from?

WESTMINSTER — Even as we delight in watching water dance across the riffles in a river, we fear floodwaters sweeping all before them.

We treasure a summer afternoon at a lake or seashore, splashing, boating, fishing, or swimming, but our need for clean water goes far beyond fear or pleasure.

Despite all the water around us, we seldom consciously think about how often we need clean water.

We use water to wash our food, our possessions, and ourselves. We cook our food in water; we constantly drink water in various forms and dispose of our waste with it. We rely on water in our basic manufacturing processes; we conduct commerce on water and harvest food directly from it.

We play in, on, and under water. The life process of our bodies would be impossible without water. Water is necessary to our lives on a lifetime, daily, hourly, instantaneous basis. We cannot substitute any other known substance for water.

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For all the importance of water to all species, we do not know where it came from or how there came to be so much of it. (Oceans cover 70 percent of Earth's surface.)

The source or sources of water is one of those questions that seem to have no answer. Actually, this question currently has three theories, none of which has identified conclusively the source of water on Earth.

The first theory contends that the Earth formed with water attached to the dust particles that accreted to form the planet. Others claim that the planet came by water through asteroid and comet collisions. The third and least-documented theory suggests that early plants created water as a byproduct of photosynthesis.

All these theories involved what might have happened during the earliest eras of the Earth.

The accretion theory holds that the dust particles that formed the Earth 4.7 billion years ago contained grains of a common mineral, olivine. The solar system temperature was roughly 7,500 degrees Fahrenheit. The Earth should have been baked dry, but olivine holds on to the oxygen in water molecules at temperatures hotter than 1,100 degrees F.

As the theory goes, Earth increasingly accreted these particles in its formation and water came along with them. Then, as Earth began to cool, the minerals solidified and crystallized in the mantle, leaving most of the water behind in the fluid magma.

Eventually over the eons, the trapped water became so concentrated that it bubbled out of the molten magma, producing a steamy atmosphere that condensed and fell as rain on the surface. Some even claim that there are oceans of water still trapped in the molten magma in the inner Earth.

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The most commonly accepted theory, though, has the Earth receiving its water from interstellar bodies through collisions with comets and asteroids. If they were the source, then something had to hurl the interstellar bodies toward the Earth.

The prime suspect is the huge planet Jupiter, which is thought to have gone rogue, leaving its circular orbit and taking on an elliptical orbit in the early eons of the solar system due to gradational effects of the equally massive Saturn.

Jupiter cut across the solar system and then went shooting far our beyond our solar system. Once in this gigantic elliptical orbit, its massive gravitational strength could have pulled icy outer-solar-system asteroids and comets from the asteroid belt into elliptical orbits aimed inward toward the sun. On their travels, some would bash into the Earth and bring their water with them.

Although speculations in this vein always include comets and asteroids together, there are now some questions about the comet part of the theory.

Scientists have found that water found on and in comets does not match the chemical makeup of the water in our oceans. Asteroids hold water that is a better chemical match. These supposed collisions happened so early in Earth's existence that no impact craters remain to prove any of it.

The most speculative theory offers that when plants first began photosynthesis, the reactions were different from those in plants today because our atmosphere then lacked oxygen and was made up of carbon dioxide heavily mixed with hydrogen sulfide.

These chemical compounds, when run through photosynthesis, make water a much larger byproduct of the natural chemical reaction. Now, in our oxygen-rich atmosphere, the reaction has changed, and the addition of new water to the earth from plants is negligible.

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So out of this shroud of mystery came a substance found everywhere on and around the Earth with properties that are vital for all life as we know it.

Regardless of the ultimate source of water, there is a finite amount. Only a minuscule 2 percent is fresh water, and we don't expect to see any more water come our way.

So what we have is what we get.

That's a good reason to take care of all of it.

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