Unit Background
Why is water important?
When you see Earth's image from an astronaut's window overlooking space, Earth is covered mostly with water. It is the only planet that has liquid water on it. History tells us that even the early man learned the he could not live without water. Man's thirst led him to live close to water. Water was also his source of food. He knew that water was important to every living organism. Man, plants and animals needed water for food. Where there is water, life exists.
Man knows that water is needed for life. Every living organism contains water. The human body is composed of 75 percent water, which is also true for animals and trees. 6 The main part of the blood is mostly water. The brain, muscles, skin and all body tissues contain water. As the saying goes, man can live without food for many weeks, but he can live only for a few days without water.
What is water?
In chemistry, water is made up of two invisible gases, hydrogen and oxygen. There are two parts of hydrogen and one part of oxygen. Hydrogen is the simplest and lightest of all elements. It is a nonmetallic element. Hydrogen is the most abundant element in the world. Hopefully it will become important in the study of fuel cells to generate electricity because it is a clean and efficient element. Oxygen, on the other hand, is also a non-metallic element. It is colorless, odorless and tasteless. It is one of the most significant elements behind most chemical reactions because it is important to life processes. When we inhale, oxygen gets into our bloodstream and our blood cells carry oxygen to sustain chemical reactions in our body.
There are three states of matter namely solid, liquid and gas. Water has three different forms. When the water is frozen, it is in its solid state. The freezing point of water is 32 degrees Fahrenheit and 0 degrees Celsius. When you put water in the freezer, ice forms. Ice also forms during cold winter time on ponds, rivers and lakes. When water freezes it expands. A cubic foot of water makes more that a cubic foot of ice. That makes ice lighter than the same amount of water. In winter, ponds are only frozen on the top. Fish and other living organisms swim and feed in the water below. If ice were heavier than water, then ponds would freeze from the bottom to the top. All living creatures would also freeze. The fish would all die.
When ice melts, water turns to its liquid state. Water boils at 212 degrees Fahrenheit and 100 degrees Celsius. When water boils it turns into a gas called steam. The steam is invisible and, as it cools down, tiny drops of water formed. We would see tiny clouds. Clouds are water vapors. They are formed when warm, moist air rises and is cooled. There are billions and billions of droplets of water which create moisture. Air is never entirely dry because of the moisture that surrounds the Earth.
Water has three classes of characteristics namely physical, biological and chemical. The physical characteristics of water are temperature, taste, odor, and turbidity. Water is a colorless substance. The sea waters look blue because of the sun's light. The colored light rays are reflected by water molecules. This is also true for the ocean waters that look green.
The biological characteristics of water refer to different organisms found in it. These organisms are microscopic viruses, bacteria, protozoa, and phytoplankton, zooplankton which are the tiny water animals, insects, worms, large plants and fish. Humans are affected by the disease causing bacteria and viruses which could be present in water. These species that infect humans and animals are called pathogens. Pathogens can enter the water system through the sewage. Scientists conduct tests to determine contaminated water. They measure a certain bacteria called fecal coliforms. Coliforms are found in the intestines of mammals. The presence of coliforms in water indicates that sewage is present and there may be other disease causing organisms.
The Alberta Environment research states that water has many chemical characteristics. 7 Substances that dissolve in water also contribute to chemical water characteristics. The chemicals found in water include the gases oxygen and carbon dioxide, salts, substances that stimulate plant growth (nitrates and phosphorus) and other man-made substances. Due to the plumbing fixtures, iron and manganese are found in ground water. Dioxins and furans are only tested after an investigation has been made from the source of these chemicals. Water testing for these two chemicals is costly. Dissolved Oxygen is an important factor that determines the types of organisms that can survive. Trout will survive in the right amount of dissolve oxygen found in clean water, that is without the presence of toxic chemicals. Chemical testing is routinely done for dissolved oxygen, pH and phosphorous values.
The quality of water changes depending on the nature or human activities. On average, each person uses about 80-100 gallons per day in the United States. 8 Water consumption is high when we use it for flushing the toilets, washing and bathing ourselves, our clothes, dishes, cars, and our homes. It takes 4-6 gallons to flush the toilet, 6-12 gallons to wash dishes, 25-30 gallons to take a shower, 30-40 gallons to take a bath, 30-50 gallons per load to wash clothes, 60 gallons to wash the car, 150 gallons to produce one Sunday newspaper, and 100-200 gallons to water the lawn. 9 Two gallons per person per day are used for drinking and cooking. If we multiply the amount of water for the whole population, we will come up with billions of gallons water used daily. That figure does not even include the water usage in farm irrigation, and operation of factories. For instance, according to research, it takes 63 gallons of water to produce one egg. 1 0 Count the amount needed to grow food for the hen, and the water that the hen drinks. To produce one-quarter pound of hamburger, it would take 625 gallons of water. 1 1 A pound of beefsteak would take 1200 gallons of water. 1 2 It takes a gallon of water to equal a gallon of gasoline by volume. 1 3 To manufacture a ton of steel, it would take almost 62,600 gallons. 1 4 Put all these figures together and that would approximately give a total of almost 500 billion gallons every day.
We are so fortunate that in our country, water supply is abundant. There is so much water that flows out of the faucet and it seems like our water will never run out. Canada and Europe also have abundant water supplies. However, in other parts of the world, the people are experiencing water shortages, drought, and people have to walk hours to get drinking water from wells which are contaminated with pathogens. In some places, bacteria and coliforms are present. Their water supply causes illnesses and diseases for humans and animals.
Water supply for our daily needs comes from rivers, lakes and reservoirs. Reservoirs are man-made lakes. Water is also found under the ground. Ground water is stored in layers of rocks, sand and soil. Humans and animals need fresh water which is free of salt, chemicals and pathogens. Water can only be purified and renewed through the water cycle. The water cycle goes from precipitation, evaporation, condensation and the cycle goes on and on. Precipitation is when rain falls into lakes and stream. Used water goes underground or into a sewage system. Then the water flows back to the lakes, streams and rivers and some of it evaporates into the air. Water evaporates from the oceans, from trees and plants, from animals and humans. This is when water becomes water vapor which is a gas.
During condensation the water vapor cools. One drop of water contains about 100,000 water droplets. Clouds are made up of water droplets. The wind blows the clouds to different places. When the water droplets become heavy, they fall as rain or snow. Although some water impurities are picked up during evaporation, water remains clean. Water is useful again for our homes, farms and industries.
Drinking water today is the same water that was here when the dinosaurs roamed the Earth. Water is still made of the same molecules. Water evaporates, condenses and precipitates in the form of rain or snow. That is the same water that was present millions of years ago. We depend on the water cycle because it renews and purifies our water supply. There are times when there is no rain, which decreases the water level in our rivers and lakes. When drought happens, people are asked to conserve water or take the risk of running out.
I have mentioned earlier that humans, plants and animals need water. However, there are other organisms that need water too. The way we live affects the quality of water as well as the health of the organisms. For example, toxic chemicals that are not Earth friendly reduce the amount of oxygen available for the organisms. Bacteria consume a lot of oxygen when organic waste is broken down. Oxidation occurs when some of the compounds in the waste change chemically because oxygen is present in the water. Therefore, the organisms that can live in lower quality of water survive and those organisms that cannot tolerate the reduced level of oxygen will die or move away.
Branley describes one of the issues of water emergencies that occur in northern New Jersey. 1 5 There are few lakes and reservoirs in that area. During the winter, water in the form of rain and snow is collected in the reservoirs. When droughts occur, the water in reservoirs is not enough for its people, plants, animals and industry. Water must be taken from other resources. In the year 1980 - 1981, there was a drought in New Jersey. Water pipes carried water from other lakes in the northern states to New Jersey reservoirs. The water was taken from other places where people were living in summer cottages, called recreational centers, and residents who needed water for their own use. This was not a good solution because water from the lakes was drained. Residents in the area did not have enough water for their own use.
When a problem like this occurs, the solution is to build more reservoirs and to build long pipelines to carry water from faraway lakes. New York City has built long pipes to provide water to everyone. In 2006, the city consumed about 1.086 billion gallons of water average per day. 1 6 Aqueducts carry the water to as far as 100 miles from different lakes and reservoirs in upper New York State. This is also true for California. The Colorado River and reservoirs located in the mountain east of the state supply California with water. The residents of New Jersey, New York City, and California hope for heavy snows in the winter. When snow melts the water will fill the reservoir.
According to statistics, the human population is increasing every year. So whenever population increases, the consumption of water also increases. Farmers have to grow more crops and use water to irrigate their farms. The acre foot is the common measure for large quantities of water and is approximately 325,851 gallons. 1 7 So a 60 acre farm requires thousands of gallons of water each planting season. 1 8 The demand of water has increased remarkably. People use water at a very high level. There are about two million dams built to store water. Millions and millions of well have been dug to bring ground water to the surface. 1 9 For instance in Houston, Texas, there is a place where the ground has sunk because the pumping of so much water affected the land. As a result, many houses sank in sink holes and the residents had to find new homes.
Water is very important to us and it should not be taken for granted. When water becomes scarce we realize that life cannot go on. Humans, plants and animals need good water. The effect of not having enough water will be disastrous. The entire place will just be a wasteland. I could not imagine what life will be like when I turn on my faucet and not a drop of water comes out. There is one place in the world where the cleanest water is found. Russia has many lakes. One of the famous lakes is Lake Baikal. It is the deepest lake found in the world and also known as the largest fresh water lake. It has the purest water and that is why one will find 1700 species of plants and animals. 2 0 Two thirds of these flora and fauna are not found anywhere else. Baikal is considered as the oldest lake in the world. The lake is isolated and surrounded with mountains. The water in the lake is well-mixed and well oxygenated. The lake supplies water to the local population.
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