Other than air nothing is more important to life than water. We delight in water as it skips across the riffles in a river. In flood, you feel the ancient fear as water sweep all before it. Beyond our delight in a summer afternoon at a lake or seashore, splashing, fishing or swimming in the water our sense of water should be primal.
Despite all the water around us we seldom think about how often we require clean water in our lives. We use water to wash our food, our possessions and ourselves. We cook our food in water; constantly drink water in various forms and dispose of our waste with water. We rely on water in our most basic manufacturing processes; conduct commerce on water and harvest food directly from it. We play in, on and under water. Water is necessary to our lives on a lifetime, daily, hourly, minute-to-minute basis and we cannot substitute any other known substance for water.
Water is so basic to our existence that in antiquity it was considered an element along with air, fire and earth. The ancients were not far wrong, water is unique. Water exists as a solid, liquid and gas at normal atmospheric and temperature conditions at the surface of the earth. Few substances have this capacity and none compose as large a part of the earth. This marvelous ability of water to move between these three physical states allows for the hydrologic cycle of rain, running down to rivers, into lakes or the ocean and then evaporating to again become rain restarting the cycle. Without water falling on the land our woods, grasses, and crops could never support our lives.
It is the ability of water to dissolve solids, liquids and gases into itself is vital to life. A substance that can dissolve a wide array of other substances is known as a “universal solvent.” Few substances other than water are universal solvents and those that are, such as alcohol and benzene are toxic to organic life forms. Water in proper amounts is harmless to virtually all life forms.
The ability of water to dissolve solids and liquids allows the cells in our body to be fed and dispose of the wastes they generate in the life process. Fortunately, as excellent a solvent as water is, it does not dissolve calcium or phosphorous, otherwise our bones would liquefy. One fact we all learn at an early age is that 70% of our body is composed of water. A loss of water from our bodies, even as slight as 12%, can bring death.
If water did not dissolve gasses there could be no aquatic life. An attribute of water that relates to the health of all forms of aquatic life is the change in the capacity of water to dissolve substances as its temperature changes. As water heats up most solids and liquids dissolve more easily in water. However gasses, such as oxygen dissolve less easily in warmer water. Dissolved oxygen levels can drop below requirements for aquatic life if water is too warm.
Water is composed of hydrogen and oxygen, but the bond between these two elements is unusual in the world of science. Unlike most compounds once water forms there remains a little extra bonding power left over. This residual bonding power allows water molecules to form “hydrogen bonds” with other water molecules. Each molecule of water is attracted to and holds onto any water molecule near it. This extra bonding power means that a beaker of water, a lake or for that matter oceans can be thought of as one single assemblage of water. It is also why a “belly flop” dive hurts. The grip of one water molecule to another makes the surface of water is inelastic.
Water is one of the few substances found anywhere in nature that expands as it freezes and that expansion means ice weighs roughly 90% the weight of liquid water. Consequently ice floats on water so lakes and rivers freeze from the top down not from the bottom up. If it were otherwise aquatic creatures living in cold climates could not exist. A frozen bottom would mean that water cannot flow over, under and around the rocks and cobble on the bottom of rivers and lakes depriving aquatic organisms of oxygen and food.
For all the importance of water to us and other species, we do not know where it came from nor how there came to be so much of it to where it covers three quarters of the Earth. Several theories exist that involve the accretion of water molecules during the formation of the earth and/or comet and asteroid strikes and/or as a waste product of the earliest living organisms over the four billion years of the Earth’s existence but there is no agreement that any of the theories adequately explain the existence of all this water on the earth.
Out of this shroud of mystery comes a substance found everywhere on or around the earth with properties that are necessary for all life as we know it. Water is truly a wonder substance.
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David Deen is River Steward for the Connecticut River Watershed Council. CRC has been a protector of the Connecticut River for more than half a century.
