About Water.
About Water, odorless, tasteless, transparent liquid that is colorless in small amounts but exhibits a bluish tinge in large quantities. It is the most familiar and abundant liquid on earth. In solid form (ice) and liquid form it covers about 70% of the earth's surface. It is present in varying amounts in the atmosphere. Most of the living tissue of a human being is made up of water; it constitutes about 92% of blood plasma, about 80% of muscle tissue, about 60% of red blood cells, and over half of most other tissues. It is also an important component of the tissues of most other living things.
Chemical and Physical Properties. Chemically, water is a compound of hydrogen and oxygen, having the formula H 2 O. It is chemically active, reacting with certain metals and metal oxides to form bases, and with certain oxides of nonmetals to form acids. It reacts with certain organic compounds to form a variety of products, e.g., alcohols from alkenes. Water has interesting thermal properties. When heated from 0°C, its melting point, to 4°C, it contracts and becomes more dense; most other substances expand and become less dense when heated. Conversely, when water is cooled in this temperature range, it expands. It expands greatly as it freezes; as a consequence, ice is less dense than water and floats on it. Because of hydrogen bonding between water molecules, the latent heats of fusion and of evaporation and the heat capacity of water are all unusually high. For these reasons, water serves both as a heat-transfer medium (e.g., ice for cooling and steam for heating) and as a temperature regulator (the water in lakes and oceans helps regulate the climate.)
Over two thirds of Earth's surface is covered by water; less than a third is taken up by land. As Earth's population continues to grow, people are putting ever-increasing pressure on the planet's water resources. In a sense, our oceans, rivers, and other inland waters are being "squeezed" by human activities—not so they take up less room, but so their quality is reduced. Poorer water quality means water pollution.We know that water pollution is a human problem because it is a relatively recent development in the planet's history: before the 19th century Industrial Revolution, people lived more in harmony with their immediate environment. As industrialisation has spread around the globe, so the problem of pollution has spread with it. When Earth's population was much smaller, no one believed pollution would ever present a serious problem. It was once popularly believed that the oceans were far too big to pollute. Today, with over 8 billion people on the planet, it has become apparent that there are limits. Pollution is one of the signs that humans have exceeded those limits. How serious is the problem? According to the environmental campaign organization, "Pollution from toxic chemicals threatens life on this planet. Every ocean and every continent, from the tropics to the once-pristine polar regions, is contaminated." Pure Water for life Life began on Earth about a billion years later (3.6 billion years ago), initially in the oceans. Although many species now live on land, they still need water to live and grow: humans, for example, could go without food for about two months, but we'd die of thirst if we went more than a week or so without a drink. Typically we need at least 2 liters of water a day to survive, though we get much of this from things we eat as well as things we drink. Eggs are about three quarters water, for example, while fruits such as oranges and melons are over 90 percent water. Pour yourself a glass of water and you could be drinking some of the same molecules that passed through the lips of Julius Caesar, Joan of Arc, Martin Luther King, or Adolf Hitler. Indeed, since the human body is about 60 percent water you might even be drinking a tiny part of one of those people! Water is one of the most amazing things about Earth—without it, there would be no life and our planet would be a completely different place—and one of the truly amazing things about water is that it's never used up: it's just recycled over and over again, constantly moving between the plants, animals, rivers, and seas on Earth's surface and the atmosphere up above.
US Mayors Agree to Phase Out Bottled Water
The US Conference of Mayors on Monday passed a resolution calling for a phasing out of bottled water by municipalities and promoting the importance of public water supplies.
The vote comes amid increasing environmental concerns about the use of bottled water because of its use of plastic and energy costs to transport drinking supplies.
“Cities are sending the wrong message about the quality of public water when we spend taxpayer dollars on water in disposable containers from a private corporation,” said Newsom. “Our public water systems are among the best in the world and demand significant and ongoing investment.” According to the activist group Think Outside the Bottle, more than 60 mayors in the United States have already canceled bottled water contracts. “It’s just plain common sense for cities to stop padding the bottled water industry’s bottom line at taxpayer expense,” said Gigi Kellett, national director of the Think Outside the Bottle campaign. “This resolution will send the strong message that opting for tap over bottled water is what’s best for our environment, our pocketbooks and our long-term, equitable access to our most essential resource.” The American Beverage Associations called the resolution “tainted with hypocrisies and inaccuracies.” “While some mayors oppose the use of bottled water by city governments, most mayors across America gladly welcome bottled water when disaster strikes,” the industry group said in a statement. “Our beverage companies continually come to the aid of communities ravaged by floods, fires, hurricanes, other natural disasters and compromised municipal water systems.” The group said plastic water bottles “are 100 percent recyclable, making bottled water one of the few fully recyclable consumer goods.” © 2008 Agence France Presse Information retrieved from www.commondreams.org Information retrieved from Commondreams.org |