Monday, September 15, 2014

Chemical Faithfulness, Part 2: How Water Shapes Geology and Biology

In Part 1 of this series I wrote about the chemical power hidden in a glass of water, and how, chemically speaking, water is truly the “living water” of Scriptural metaphor. Living water is creative -- its flow shapes both your feet and the ground beneath them.

Every place on Earth, even the driest desert, has been shaped and washed by the power of water. Twenty years ago when I moved from Florida to Seattle, I moved from one place shaped indelibly by water to another.

In Seattle, our rainfall is famous. Our familiarity with water also runs deep in time. Long ago frozen water carved the landscape of the Pacific Northwest with flowing, “living” glaciers. Long ago, an advancing ice sheet from Canada traveled southwest and ran into the Olympic mountains around where Vancouver is today. The mountains stood firm, cracking the ice in two. One sheet turned west and joined the Pacific, carving the Strait of Juan de Fuca. The other turned south and scooped out the Puget Sound.

In Florida, the water is different, both temperamental and constant. Routine 4pm summer thunderstorms suddenly pour down rain that pools in your sandals, then just as suddenly stop. There are no glacial valleys in Florida, but there are miles of beaches, rock atomized by surf. The water has also carved deep aquifers underneath Florida, which would stay hidden if not for the occasional sinkhole.

All this power is wrapped up in a tiny package. Water is the mustard seed of molecules. It is composed of two hydrogens and one oxygen, bonded with electrons, as H2O.

You can make a molecular model of water with two grapes (for the hydrogens), two toothpicks (for the shared electrons), and a plum (for the oxygen). If you can make the grapes stick out from the plum with an angle of 104.5°, then you have just made a scale model of the molecule that carved Seattle’s valleys and fills Florida’s aquifer. In a sense, you’d be making the model of water from water -- the fruit that you’d be using to make this model is mostly water itself, sweetened with some natural sugar.
Water may be small but this makes it more exceptional, because it is small yet liquid. It’s always easier for a bunch of molecules to go to extremes than to sit in the middle.  It’s easy for big molecules to stick together tightly and freeze (to become solid) or for small molecules to fly apart in a thousand directions (to become gas). It’s not easy for a molecule to find an inbetween state, neither too hot nor too cold, close enough to touch and yet energetic enough to slide around, flowing as a liquid, condensing into an ocean. Life needs to be in this inbetween state, its atoms coherent yet always in motion. Therefore, life as we know it needs water, and you are alive because of the liquid water in you.

If liquids are living, then the universe is mostly dead, because liquids are rare. Looking at the periodic table, only two elements out of more than 100 are liquid at room temperature: mercury and gallium. Likewise, most molecules as small as water are gases. Big, complex molecules are harder to make. Here on earth, only water is the only molecule that combines liquidity with simplicity, and we literally have oceans of it.

Oceans are Earth’s defining characteristic in the solar system, a gift to our planet that changes its distant color to that of a “pale blue dot,” perceptibly different from yellow Venus and red Mars. Oceans made our rocks different as well. The geologist Robert Hazen estimates that the action of water on the Earth brought about more than 3000 new minerals when there were only about 500 before, a multiplication of diversity in the rocks from this one chemical.

Jade, sapphire, emerald, all were made when water mixed and reacted with the Earth. Mother lodes of ores are found by following the ancient paths of water to where precious metals were deposited. Panning for gold requires a stream of running, living water.

Look at a drop of water in a microscope and you’ll see another way it is “living” water. Even the most crystal-clear pond water is home to thousands of undulating, spinning, pulsing amoebae and protozoa, a microscopic menagerie. Remove all of these, looking even closer at the atoms in water, and you would see that water is constantly moving around itself, forming, unforming, and reforming bonds, in what Bill Bryson described as a “quadrille.” This movement is unbridled, even joyful.

Liquid water hosts life even in extreme conditions. In the deepest parts of the oceans, ecosystems hidden from the sun cluster around bubbling clefts where hot, energy-laden gases escape from the earth. These vents are rich with crabs, lobsters, octopi, pale white dappled with red. Six-foot-long tube worms waving like ghostly grass. These animals bask and feed on the sulfurous energy of the earth itself, mediated by the water, which is only kept liquid at such intense temperatures by the massive pressure of the fathoms above.

The DNA of these animals can be read like a book, and it matches the DNA of more familiar species. The pale creatures near the vents came to that place without sun long ago, and were kept alive by the water and the earth’s energy. Eventually they lost what they didn’t need -- pigments, eyes, and in the case of the tube worms, even mouths (they let the bacteria that live inside them eat for them, which is just as strange as it sounds). Life can live without sunlight, but it cannot live without water’s liquid flow.

Life needed water and energy to survive, and it changed its form to survive, morphing in ways unthinkable and amazing. Through liquid water, life was able to fill what had previously been empty, to thrive and to surprise. That sounds like grace to me.

Deep-ocean vents may shed light on another dimension to water’s power. At that extraordinary place, living, liquid water may have shaped the first living things on this planet, bringing a good creation to life 4 billion years ago. I will describe experiments that point in this direction in part 3 of this series.

1 comment:

unkleE said...

Really enjoying this!