Water Pollution

Water pollution is the contamination of waterbodies (e.g. lakes, rivers, oceans and groundwater).Water pollution occurs when pollutants aredischarged directly or indirectly into water bodieswithout adequate treatment to remove harmfulcompounds.Water pollution affects plants and organisms livingin these bodies of water; and, in almost all cases theeffect is damaging not only to individual species andpopulations, but also to the natural biologicalcommunities.

Toxic Substance -- A toxic substance is a chemical pollutant that is not a naturally occurring substance in aquatic ecosystems. The greatest contributors to toxic pollution are herbicides, pesticides and industrial compounds

Organic Substance -- Organic pollution occurs when an

excess of organic matter, such as manure or sewage,

enters the water. When organic matter increases in a

pond, the number of decomposers will increase. These

decomposers grow rapidly and use a great deal of oxygen

during their growth. This leads to a depletion of oxygen as

the decomposition process occurs. A lack of oxygen can

kill aquatic organisms. As the aquatic organisms die, they

are broken down by decomposers which leads to further

depletion of the oxygen levels.

A type of organic pollution can occur when inorganic pollutants such as nitrogen and phosphates accumulate in aquatic ecosystems. High levels of these nutrients cause an overgrowth of plants and algae. As the plants and algae die, they become organic material in the water. The enormous decay of this plant matter, in turn, lowers the oxygen level. The process of rapid plant growth followed by increased activity by decomposers and a depletion of the oxygen level is called eutrophication.

Thermal Pollution -- Thermal pollution can occur when

water is used as a coolant near a power or industrial plant and then is returned to the aquatic environment at a higher temperature than it was originally. Thermal pollution can lead to a decrease in the dissolved oxygen level in the water while also increasing the biological demand of aquatic organisms for oxygen.

Ecological Pollution -- Ecological pollution takes place when chemical pollution, organic pollution or thermal pollution are caused by nature rather than by human activity. An example of ecological pollution would be an increased rate of siltation of a waterway after a landslide which would increase the amount of sediments in runoff water. Another example would be when a large animal, such as a deer, drowns in a flood and a large amount of organic material is added to the water as a result. Major geological events such as a volcano eruption might also be sources of ecological pollution.

POINT AND NONPOINT SOURCES

Point sources of pollution occur when harmful substances are emitted directly into a body of water. The Exxon Valdez oil spill best illustrates a point source water pollution.

A nonpoint source delivers pollutants indirectly through environmental changes. An example of this type of water pollution is when fertilizer from a field is carried into a stream by rain, in the form of run-off

Farming:•Farms often use large amounts of herbicides and pesticides, both of which are toxic pollutants. These substances are particularly dangerous to life in rivers, streams and lakes, where toxic substances can build up over a period of time.•Farms also frequently use large amounts of chemical fertilizers that are washed into the waterways and damage the water supply and the life within it. Fertilizers can increase the amounts of nitrates and phosphates in the water, which can lead to the process of eutrophication.

•Allowing livestock to graze near water sources often results in organic waste products being washed into the waterways. This sudden introduction of organic material increases the amount of nitrogen in the water, and can also lead to eutrophication.•Four hundred million tons of soil are carried by the Mississippi River to the Gulf of Mexico each year. A great deal of this siltation is due to runoff from the exposed soil of agricultural fields. Excessive amounts of sediment in waterways can block sunlight, preventing aquatic plants from photosynthesizing, and can suffocate fish by clogging their gills.

Business:

•Clearing of land can lead to erosion of soil into the river.•Waste and sewage generated by industry can get into the water supply, introducing large organic pollutants into the ecosystem.•Many industrial and power plants use rivers, streams and lakes to dispose of waste heat. The resulting hot water can cause thermal pollution. Thermal pollution can have a disastrous effect on life in an aquatic ecosystem as temperature increases decrease the amount of oxygen in the water, thereby reducing the number of animals that can survive there.

•Water can become contaminated with toxic or radioactive materials from industry, mine sites and abandoned hazardous waste sites.•Acid precipitation is caused when the burning of fossil fuels emits sulfur dioxide into the atmosphere. The sulfur dioxide reacts with the water in the atmosphere, creating rainfall which contains sulfuric acid. As acid precipitation falls into lakes, streams and ponds it can lower the overall pH of the waterway, killing vital plant life, thereby affecting the whole food chain. It can also leach heavy metals from the soil into the water, killing fish and other aquatic organisms. Because of this, air pollution is potentially one of the most threatening forms of pollution to aquatic ecosystems.

How do we know when water is polluted?

Some forms of water pollution are very obvious: everyone has seen TV news footage of oil slicks filmed from helicopters flying overhead. Water pollution is usually less obvious and much harder to detect than this. But how can we measure water pollution when we cannot see it? How do we even know it's there?There are two main ways of measuring the quality of water. One is to take samples of the water and measure the concentrations of different chemicals that it contains. If the chemicals are dangerous or the concentrations are too great, we can regard the water as polluted. Measurements like this are known as chemical indicators of water quality. Another way to measure water quality involves examining the fish, insects, and other invertebrates that the water will support. If many different types of creatures can live in a river, the quality is likely to be very good; if the river supports no fish life at all, the quality is obviously much poorer. Measurements like this are called biological indicators of water quality.

People throw their garbage into lakes and rivers.

When this garbage decays, oxygen which is needed

by fishes and aquatic plants will be used up. As a

result ,these fishes and aquatic plants will die soon.

Factories throw their chemical wastes into the bodies of water. These harmful chemicals such as lead, mercury, and arsenic acids pollute the water of the rivers. Fish, mussels (tahong) , and other aquatic animals growing in it could eat these chemicals. The people who eat these aquatic animals could get poisoned.

Washing clothes and dishes in the rivers and lakes is also not a good practice. The detergents used by the people for washing could poison the fish and the other aquatic animals and plants living in them.

Fertilizers sprayed by people on their plants could also pollute the bodies ofwater. When it rains , these chemicals will find their way into the rivers and seas.With the abundance of nutrients and organic matter in the water, many algaeand other plants will then reduce the oxygen content of the river and the otherbodies of water. The result is the death of fish and other aquatic animals.

The crude oil that spills from boats and ships pollutes the seas and oceans, too. Whenthey cover the surface of water , the oxygen from the air cannot dissolve in it . Aquaticanimals that rely on oxygen to live will not be able to breathe. They will soon die.

When people continuously do these practices, manymicroscopic organisms called dinoflagellates will grow inbodies of water. These organism produce poisonoussubstances which give a reddish color to the water. Thisis known as the Red Tide. When Red tide is present ,many of our fishes , mussels , and other shells foods areaffected . It can even cause their death.

How can we stop water pollution?

There is no easy way to solve water pollution; if there were, it wouldn't be so much of a problem. Broadly speaking, there are three different things that can help to tackle the problem—education, laws, and economics—and they work together as a team.

EducationMaking people aware of the problem is the first step to solving it. In the early1990s, when surfers in Britain grew tired of catching illnesses from waterpolluted with sewage, they formed a group called Surfers Against Sewage toforce governments and water companies to clean up their act. People who'vegrown tired of walking the world's polluted beaches often band together toorganize community beach-cleaning sessions. Anglers who no longer catch somany fish have campaigned for tougher penalties against factories that pourpollution into our rivers. Greater public awareness can make a positivedifference.

Laws

One of the biggest problems with water pollution is its transboundary nature.Many rivers cross countries, while seas span whole continents. Pollutiondischarged by factories in one country with poor environmental standards cancause problems in neighboring nations, even when they have tougher lawsand higher standards. Environmental laws can make it tougher for people topollute, but to be really effective they have to operate across national andinternational borders. This is why we have international laws governing theoceans, such as the 1982 UN Convention on the Law of the Sea (signed by over120 nations), the 1972 London Dumping Convention, the 1978 MARPOLInternational Convention for the Prevention of Pollution from Ships, and the1998 OSPAR Convention for the Protection of the Marine Environment of theNorth East Atlantic. The European Union has water-protection laws (known asdirectives) that apply to all of its member states. They include the 1976Bathing Water Directive, which seeks to ensure the quality of the waters thatpeople use for recreation. Most countries also have their own water pollutionlaws. In the United States, for example, there is the 1972 Water PollutionControl Act and the 1974 Safe Drinking Water Act.

Economics

Most environmental experts agree that the best way to tackle pollution isthrough something called the polluter pays principle. This means thatwhoever causes pollution should have to pay to clean it up, one way oranother. Polluter pays can operate in all kinds of ways. It could mean thattanker owners should have to take out insurance that covers the cost of oilspill cleanups, for example. It could also mean that shoppers should have topay for their plastic grocery bags, as is now common in Ireland, toencourage recycling and minimize waste. Or it could mean that factoriesthat use rivers must have their water inlet pipes downstream of theireffluent outflow pipes, so if they cause pollution they themselves are thefirst people to suffer. Ultimately, the polluter pays principle is designed todeter people from polluting by making it less expensive for them to behavein an environmentally responsible way.

Our clean futureLife is ultimately about choices—and so is pollution. We can live with sewage-strewn beaches, dead rivers, and fish that are too poisonous to eat. Or we can work together to keep the environment clean so the plants, animals, and people who depend on it remain healthy. We can take individual action to help reduce water pollution, for example, by using environmentally friendly detergents, not pouring oil down drains, reducing pesticides, and so on. We can take community action too, by helping out on beach cleans or litter picks to keep our rivers and seas that little bit cleaner. And we can take action as countries and continents to pass laws that will make pollution harder and the world less polluted. Working together, we can make pollution less of a problem—and the world a better place.