Water pollution is increasingly becoming a large problem that we as humans need to confront. Water is our most valuable resource. Just think of how much we humans are dependent upon clean water. Water is way more valuable than gold, what can you go a day, week, year with out, gold or water? Besides the fact that we drink the water, we use it for irrigation of farm fields, cooking, washing clothes, flushing toilets, etc. and every industrial process requires water to function. Everyone knows that the Earth's surface is covered by 70% water, so why fuss of protecting water? Only 3% of all water is fresh and drinkable and of that 3%, 75% is frozen, which leaves a grand total of only 1% of the Earth's surface water that is readily available for consumption. After taking that fact into account, one can see why the conservation and protection of our remaining water supply is so vital. Before water pollution
can be stopped, the sources of the pollution must be known.
The major sources of water pollution are organic pollution, agricultural pollution, runoff, toxic waste, and thermal pollution. Organic pollution is becoming more and more pressing on the environment
, because of the growing population of the world. It's a simple concept, the more people there are in one area, the more waste they will produce. For example, in a city there are so many people that the sewage plants and the environment can't take care of all of the waste and function in its usual manner. The sewage plants do their best, but the secondary discharge that gets into the water supply causes great problems. The excess waste acts as a fertilizer or food source
for algae and the growth rate is uncontrollable. Everyone has been in a lake where there is a lot of dead algae on the shore and the water is clouded with algae. This situation is known as eutrophication, where algae growth is out of control and the water becomes oxygen depleted. There are natural cycles of eutrophication in the spring and fall, but the body of water can deal with those amounts. When excess waste is added to the water the body of water can no longer control the growth of the algae and the water soon becomes algae ridden and oxygen depleted. The water becomes oxygen depleted, because the dead algae goes to the bottom and uses the oxygen in the deeper water to decompose, but if there is too much dead algae all the oxygen is depleted. Oxygen from the surface doesn't reach the bottom, because the warmer water is less dense than the deeper cooler water, therefor the warmer water floats on the colder water and they never mix, much like oil and water. Soon the dead algae piles upon itself and makes the lake shallower, until it totally fills in and dries up.
Eutrophication effects all bodies of water, great and small. In the summer of 1971 at the Chicago South Water Filtration Plant on the coast of Lake Michigan, the filters were clogged with so much algae it had to be removed by hand. In the winter the turbidity(sediment in the water) was so high that the water wasn't drinkable. In a third case, the water smelled and tasted like dead fish and huge amounts of chlorine had to be added to make the water drinkable. If eutrophication can happen in lakes like Lake Michigan and Lake Erie, than no lake is safe. When eutrophication become extreme the water isn't usable any more. To stop the eutrophication of our lakes we need to devise a better system to treat sewage so it can be reused or released back into the environment without a catastrophic reaction. Currently there are some new systems that take raw sewage and convert it into usable water through biological means. The plant takes the water and feeds it to various plants. The nutrients are taken from the waste and used to grow plants. The excess water becomes clean after a four day operation. This idea is like controlled eutrophication where the plants are feed the excess nutrients to get plant growth instead of algae growth. This has only be attempted on a small scale. In the future if this could be done on a large scale the plants that are feed the waste to clean the water could be used as a food source. This idea isn't very new, infact, it is millions of years old. Basically the new sewage plant is an artificial wetland.
A wetland as defined by the American Heritage Dictionary, "a lowland area, such as a marsh or swamp, that is saturated with moisture, especially when thought of as the natural habitat for wildlife." Wetlands perform a very important function in nature. First off they provide habitat for a high percentage of endangered and threatened species of plants and animals. The survival of the species depends upon the survival of the wetland. When wetlands are reduced the population of water foul, fish, and animals reduces drastically. Not only are they just a home for the animals, they serve as a purification system. Water moves slowly through the wetland and the soil and the plants pick up the nutrients and contaminants and clean the water. They serve as a large filter, dirty water passes into the wetland and clean water is the final result. Wetlands also serve as water retention and flood prevention areas. If there were no wetlands all the water that is in the wetlands and the rain and snow would flood into our cities and neighborhoods. All the excess water is held in the wetlands were it is purified and slowly dispersed. Wetland act as an erosion control along coastlines and prevent wind erosion. They also safeguard that the soil will keep its nutrients. Wetlands are economically important also. Over 95% of the fish and shellfish that the US commercial industry harvest are dependent on the wetlands. Sport fishermen spend large amounts of money on fishing equipment and licensees. Valuable timber is harvested from the many forested wetland. Fur bearing mammals and alligators are harvested in wetlands. The vegetation of the wetlands can also be harvested. The US hasn't taken advantage of this option yet, but other countries such as China do. As one can see there are countless reasons for the preservation of wetlands. Wetlands need to be protected and preserved for the future. Another type of water pollution is one most people don't really think about, runoff.
Rainfall, snowmelt and irrigation cleanse the surface of the Earth. Any pollutants that are on the ground will eventually come in contact with water. So what? The water is just cleaning the streets and everything it comes in contact with, right? Wrong, the water picks up everything that is in it's path. This can range from pieces of food to motor oil to fertilizer or any pollutants that might lie on the millions of roads and expressways of the US. Now the polluted water makes its down fall into the ground water, which intern ends up in nearby streams, rivers, and lakes. This means that any pollutant left on the ground will eventually end up as contamination of the water supply. We need this water to drink and we use the rivers and lakes as recreation. Water runoff presents a major problem.
Polluted water runoff is hard to calculate, but some attribute as high as 80% to runoff. Most people think that only the big companies are to blame for the poor quality of water, but that isn't so. The large companies are regulated by the Clean Water Act. There is no way to control the amount of pollution that is taken by water runoff. Police can not find everyone that has spread their old motor oil on their driveway to keep the dust down or keep track of how often people fertilize their lawn. This is much more difficult to detect and prevent. This comes down to each persons own values and environmental values. Each individual is responsable for their actions and there is no way to police that. The average person doesn't cause any large quantities of water pollution, it comes from an unlikely source.
Larger sources of runoff pollutants come from farms and pastures. On the farms all the excess fertilizer gets into the streams and ends up in the lakes. When the fertilizer reaches the lake or stream, it cause eutrophication to occur. This means that less fish can survive and the water will go from clear to cloudy. No one wants to swim in water that you can't see your feet in. Another problem farms present is the loss of soil and sediment in rivers. The precious soil is stolen by erosion and carried off in the rivers. The lose of the soil is bad enough, but the horrible part is that along with the soil goes all of the fertilizer, pesticides and herbicide used on the fields. In other words, any chemical put on the crops to prevent animals or bugs from eating them ends up in the water we drink. In the 1960's and 1970's the pesticide DDT was heavily used. This chemical was applied on the farms and runoff took it to the lakes. The plants absorbed the DDT and then the herbivores ate the plants. The carnivores ate the herbivores and the second carnivore(Humans or birds) eat them. As the DDT moves up the food chain it intensifies and the concentration is very dense by the time it reaches the carnivores. What goes on the farm ends up in our food, one way or the other.
On ranches the problem becomes the excess of excretion from the cattle.(25,000 cattle produce 300,000 gallons of waste a day) All of this urine and manure goes straight to the ground water and right back to the rivers and lakes. At least the human waste is sent to a sewage system, which does some good. This cattle waste is being sent straight to the water supply, untreated. In Oregon, Tallamook Bay is closed to oyster growing at certin times of the year, because of the high levels of contamination from the cattle. Where do we draw the line?
Polluted runoff is hard to control. Currently there are efforts being taken to stop polluted runoff from entering the water supply, but they are all on a voluntary basis. Most people will help, but what of the others? Legislation needs to be made to enforce what some will not do. Runoff water pollution is serious and it effects everyone. Thermal pollution is simmilar to runoff in the fact that no one ever gives it any thought.
Thermal pollution occurs when the water is heated up by power plants. Fossil fuel power plants, Neucular power plants and hydrolic dams heat the water. The industrial process requires large quanities of cooling water and water runnign through danm turbines is heated. After the water is heated, it is then discharged into lakes and rivers. Certin types of fish, animals, and plankton die if the water temperature is raised to much. Fish can't spwan when the water temperature is to high. If temperatures are hot enough the life in the water becomes minimal. Also, when the water is warmed, it promotes the growth of algae. With high concentratiuons of algae, the problem of eutrophication is introduced again. Neucular power plants cause thermal pollution, but they also cause radioactive waste. Little is known about radioactive waste, but it is know that small amounts of this material can destroy life in large quanities of water. There is one last source of pollution, toxic waste.
Toxic waste comes form a great variety of industrial plants. In mining opperations and many industrial processes heavy metals such as lead, copper, cadium, iron and others are released into the water. These heavy metals accumulate in fish and make them harmful to anything that eats them and to the fish itself. In pulp-mill paper production, a combination of organic waste and toxic waste combind to cause horriable effects. As mentioned before, DDT is a toxic waste that ravashises any environment it comes in contact with. PCB's are anothe rtoxic waste that are byproducts of many industrial processes. PCB's work in the same way as DDT by concentrating as it moves up the food chain until it is highly toxic by the time it reaches Humans and other animals high on the food chain.
Water is a necessity of life and it needs to be conserved and protected. >From all of the above pollutants, our water supply is in peril. If we value life as we know it, we need to change our way of life and look at water in a different way.
Crossland, Janice. Water Pollution, Harcourt Brace Jovanovich, Inc, New York, New York, 1974.
Gosselink, James J. Wetlands, Van Nostrand Reinhold, New York, 1993.
Larkin, P.A. Freashwater Pollution Canadian Style, McGill-Queens's University Press, Montreal, 1974.
Mitchel, John G. "Our Polluted Waters." National Geographic, February 1996: pp.108-105.