Water pollution

Contents 1 Introduction 2 Specific Sources of Water Pollution 2.1 Farming: 2.2 Business 2.3 Homes 3 Types of water pollution 3.1 Surface water pollution 3.2 Ground water pollution 3.3 Microbiological water pollution 3.4 Oxygen depleting 3.5 Nutrients 3.6 Suspended matter 3.7 Chemical 4 Causes of water pollution 4.1 Sewage and wastewater 4.2 Industrial waste 4.3 Oil pollution 4.4 Atmospheric deposition 4.5 Marine dumping 4.6 Radioactive waste 4.7 Underground storage leakages 4.8 Global warming 4.9 Eutrophication 5 Dangers 6 Prevention 7 Laws and conventions 8 Water Pollution Mitigation 8.1 Industrial treatment 8.2 Septic tanks 8.3 Denitrification 8.4 Ozone wastewater treatment 9 Related Topics

[edit] Introduction

Comprising over 70% of the Earths surface, water is undoubtedly the most precious natural resource that exists on our planet. Without the seemingly invaluable compound comprised of Hydrogen and Oxygen, life on Earth would be non-existent: it is essential for everything on our planet to grow and prosper. Although we as humans recognize this fact, we disregard it by polluting our rivers, lakes, and oceans. Subsequently, we are slowly but surely harming our planet to the point where organisms are dying at a very alarming rate. In addition to innocent organisms dying off, our drinking Water has become greatly affected as is our ability to use water for recreational purposes. In order to combat water pollution, we must understand the problems and become part of the solution.

• Water pollution is contamination of water by foreign matter that deteriorates the quality of the water. Water pollution covers pollutions in liquid forms like ocean pollution and river pollution. As the term applies, liquid pollution occurs in the oceans, lakes, streams, rivers, underground water and bays, in short liquid-containing areas. It involves the release of toxic substances, pathogenic germs, substances that require much oxygen to decompose, easy-soluble substances, radioactivity, etc. that become deposited upon the bottom and their accumulations will interfere with the condition of aquatic ecosystems. For example, the eutrophication: lack of oxygen in a water body caused by excessive algae growths because of enrichment of pollutants.

Water Cycle and Pollution

• Water cycle is, simply saying, the circulation of water in earth. In fact, the water in the earth's biosphere is used and reused again and again. This is called water cycle or continuous movement of water between the earth and the atmosphere. It involves the following mechanisms:

• Evaporation: changing of water from liquid to gas
• Transpiration: Release of water vapor from plant leaves
• Condensation: changing of vapor to liquid (cooled down)
• Precipitation: Water that returns to the earth (water droplets in clouds become large enough and there comes the rain).

• According to the water cycle, naturally, water around us will be absorbed to the land (soil) and rivers will stream from the upstream to the downstream and released to the sea. In normal situation organic pollutants are biodegraded by microbes and converted to a form that brings benefits to the aquatic life. And for the inorganic pollutants, in the same situation, don't bring to much hazards because they are widely dispersed and have almost no effect to the environment which they are released to.

• In a small scale, both inorganic and organic pollutants safely decompose throughout the stream, their concentration decrease in the sea, and they don't harm the sea ecosystem and its distribution. But in an excessive scale, communities in beach and estuary will be affected by the pollutants, and can heavily harm them.

Sources and Methods

• We can classify major sources that lead to water pollution to the following categories:

• petroleum products
• synthetic agricultural chemicals
• heavy metals
• hazardous wastes
• excess organic matter
• sediment
• infectious organisms
• air pollution
• thermal pollution
• soil pollution

[edit] Specific Sources of Water Pollution

[edit] 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 increaces 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.

[edit] 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 despose of waste heat. The resulting hot water can cause thermal pollution. Thermal pollution can have a disasterous effect on life in an aquatic Ecosystem as temperature increaces decreace 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 Ecosystem.

[edit] Homes

Sewage generated by houses or runoff from septic tanks into nearby waterways, introduce organic pollutants that can cause eutrophication.

Fertilizers, herbicides and pesticides used for lawn care can runoff and contaminate the waterway. As with agriculteral fertilizers, home fertilizers can lead to the eutrophication of lakes and rivers. Improper disposal of hazardous chemicals down the drain itroduce toxic materials into to the Ecosystem, contaminating the water supplies in a way that can harm aquatic organisms. Leaks of oil and antifreeze from a car on a driveway can be washed off by the rain into nearby waterways, polluting it.

[edit] Types of water pollution

Water pollution can come from a number of different sources. If the Pollution comes from a single source, such as an oil spill, it is called point-source pollution. If the pollution comes from many sources, it is called nonpoint-source pollution.

Most types of pollution affect the immediate area surrounding the source. Sometimes the pollution may affect the environment hundreds of miles away from the source, such as nuclear waste, this is called transboundary pollution.

[edit] Surface water pollution

Surface waters are the natural water resources of the Earth. They are found on the exterior of the Earth's crust and include:

• Oceans
• Rivers
• Lakes
• These waters can become polluted in a number of ways, and this is called surface water pollution.

[edit] Ground water pollution

A lot of the Earth's water is found underground in soil or under rock structures called aquifers. Humans often use aquifers as a means to obtain drinking Water, and build wells to access it. When this water becomes polluted it is called groundwater pollution.

Groundwater pollution is often caused by pesticide contamination from the Soil, this can infect our drinking water and cause huge problems.

[edit] Microbiological water pollution

Microbiological water pollution is usually a natural form of water pollution caused by microorganisms.

Many types of microorganisms live in water and cause Fish, land animals and humans to become ill. Microorganisms such as:

• Bacteria
• Viruses
• Protozoa

Serious diseases such as cholera come from microorganisms that live in water. These diseases usually affect the health of people in poorer countries, as they do not have the facilities to treat polluted water.

[edit] Oxygen depleting

Microorganisms that live in water feed on biodegradable substances. When too much biodegradable material is added to water, the number of microorganisms increase and use up the available oxygen. This is called Oxygen depletion.

When Oxygen levels in the water are depleted, relatively harmless aerobic microorganisms die and anaerobic microorganisms begin to thrive. Some anaerobic microorganisms are harmful to people, animals and the Environment, as they produce harmful toxins such as ammonia and sulfides.

[edit] Nutrients

Nutrients are essential for plant growth and development. Many nutrients are found in wastewater and fertilisers, and these can cause excess weed and Algae growth if large concentrations end up in water.

This can contaminate drinking Water and clog filters. This can be damaging to other aquatic organisms as the algae use up the Oxygen in the water, leaving none for the surrounding marine life.

[edit] Suspended matter

Some Pollutants do not dissolve in water as their molecules are too big to mix between the water molecules. This material is called particulate matter and can often be a cause of water pollution.

The suspended particles eventually settle and cause a thick silt at the bottom. This is harmful to marine life that lives on the floor of rivers or lakes. Biodegradable substances are often suspended in water and can cause problems by increasing the amount of anaerobic microorganisms present. Toxic chemicals suspended in water can be harmful to the development and survival of aquatic life.

[edit] Chemical

Industrial and agricultural work involves the use of many different chemicals that can run-off into water and pollute it.

Metals and solvents from industrial work can pollute rivers and lakes. These are poisonous to many forms of aquatic life and may slow their development, make them infertile or even result in death. Pesticides are used in farming to control weeds, insects and fungi. Run-offs of these pesticides can cause water pollution and poison aquatic life. Subsequently, birds, humans and other animals may be poisoned if they eat infected fish.

Petroleum is another form of chemical pollutant that usually contaminates water through oil spills when a ship ruptures. Oil spills usually have only a localised affect on wildlife but can spread for miles. The oil can cause the death of many Fish and stick to the feathers of seabirds causing them to lose the ability to fly.

[edit] Causes of water pollution

[edit] Sewage and wastewater

Domestic households, industrial and agricultural practices produce wastewater that can cause pollution of many lakes and rivers.

• Sewage is the term used for wastewater that often contains faeces, urine and laundry waste.
• There are billions of people on Earth, so treating sewage is a big priority.
• Sewage disposal is a major problem in developing countries as many people in these areas don’t have access to sanitary conditions and clean water.
• Untreated sewage water in such areas can contaminate the environment and cause diseases such as Diarrhea.
• Sewage in developed countries is carried away from the home quickly and hygienically through sewage pipes.
• Sewage is treated in water treatment plants and the waste is often disposed into the sea.
• Sewage is mainly biodegradable and most of it is broken down in the environment.
• In developed countries, sewage often causes problems when people flush chemical and pharmaceutical substances down the toilet. When people are ill, sewage often carries harmful viruses and bacteria into the environment causing health problems.

[edit] Industrial waste

Industry is a huge source of water pollution, it produces pollutants that are extremely harmful to people and the environment.

• Many industrial facilities use freshwater to carry away waste from the plant and into rivers, lakes and oceans.
• Pollutants from industrial sources include:
• Asbestos – This pollutant is a serious health hazard and carcinogenic. Asbestos fibres can be inhaled and cause illnesses such as asbestosis, mesothelioma, lung cancer, intestinal cancer and liver cancer.
• Lead – This is a metallic element and can cause health and environmental problems. It is a non-biodegradable substance so is hard to clean up once the Environment is contaminated. Lead is harmful to the health of many animals, including humans, as it can inhibit the action of bodily enzymes.
• Mercury - This is a metallic element and can cause health and environmental problems. It is a non-biodegradable substance so is hard to clean up once the environment is contaminated. Mercury is also harmful to animal health as it can cause illness through mercury poisoning.
• Nitrates – The increased use of fertilisers means that nitrates are more often being washed from the soil and into rivers and lakes. This can cause eutrophication, which can be very problematic to marine environments.
• Phosphates - The increased use of fertilisers means that phosphates are more often being washed from the soil and into rivers and lakes. This can cause eutrophication, which can be very problematic to marine Environment.
• Sulfur – This is a non-metallic substance that is harmful for marine life.
• Oil – Oil does not dissolve in Water, instead it forms a thick layer on the water surface. This can stop marine plants receiving enough light for photosynthesis. It is also harmful for Fish and marine birds.
• Petrochemicals – This is formed from gas or petrol and can be toxic to marine life.

[edit] Oil pollution

Oceans are polluted by oil on a daily basis from oil spills, routine shipping, run-offs and dumping.

• Oil spills make up about 12% of the oil that enters the ocean. The rest come from shipping travel, drains and dumping.
• An oil spill from a tanker is a severe problem because there is such a huge quantity of oil being spilt into one place.
• Oil spills cause a very localised problem but can be catastrophic to local marine wildlife such as fish, birds and sea otters.
• Oil cannot dissolve in water and forms a thick sludge in the water. This suffocates fish, gets caught in the feathers of marine birds stopping them from flying and blocks light from photosynthetic aquatic plants.

[edit] Atmospheric deposition

Atmospheric deposition is the pollution of water caused by air pollution.

• In the atmosphere, water particles mix with Carbon dioxide sulphur dioxide and nitrogen oxides, this forms a weak acid.
• Air pollution means that water vapour absorbs more of these gases and becomes even more acidic.
• When it rains the water is polluted with these gases, this is called Acid Rain.
• When acid rain pollutes marine habitats such as rivers and lakes, aquatic life is harmed.

[edit] Marine dumping

Dumping of litter in the sea can cause huge problems. Litter items such as 6-pack ring packaging can get caught in marine animals and may result in death. Different items take different lengths of time to degrade in water:

• Cardboard – Takes 2 weeks to degrade.
• Newspaper – Takes 6 weeks to degrade.
• Photodegradable packaging – Takes 6 weeks to degrade.
• Foam – Takes 50 years to degrade.
• Styrofoam – Takes 80 years to degrade.
• Aluminium – Takes 200 years to degrade.
• Plastic packaging – Takes 400 years to degrade.
• Glass – It takes so long to degrade that we don’t know the exact time.

[edit] Radioactive waste

Nuclear waste is produced from industrial, medical and scientific processes that use radioactive material. Nuclear waste can have detrimental effects on marine habitats. Nuclear waste comes from a number of sources:

• Operations conducted by nuclear power stations produce radioactive waste. Nuclear-fuel reprocessing plants in northern Europe are the biggest sources of man-made nuclear waste in the surrounding ocean. * Radioactive traces from these plants have been found as far away as Greenland.
• Mining and refining of Uranium and thorium are also causes of marine nuclear waste.
• Waste is also produced in the nuclear fuel cycle which is used in many industrial, medical and scientific processes.

[edit] Underground storage leakages

A tank or piping network that has at least 10 percent of its volume underground is known as an underground storage tank (UST). They often store substances such as petroleum, that are harmful to the surrounding Environment should it become contaminated. Many UST’s constructed before 1980 are made from steel pipes that are directly exposed to the environment. Over time the steel corrodes and causes leakages, affecting surrounding Soil and groundwater.

[edit] Global warming

An increase in water temperature can result in the death of many aquatic organisms and disrupt many marine habitats. For example, a rise in water temperatures causes coral bleaching of reefs around the world. This is when the coral expels the microorganisms of which it is dependent on. This can result in great damage to coral reefs and subsequently, all the marine life that depends on it.

The rise in the Earth's water temperature is caused by global warming.

• Global warming is a process where the average global temperature increases due to the greenhouse effect.
• The burning of Fossil fuel releases Greenhouse gases, such as Carbon dioxide, into the atmosphere.
• This causes heat from the sun to get ‘trapped’ in the Earths Atmosphere and consequently the global temperature rises.

[edit] Eutrophication

Eutrophication is when the Environment becomes enriched with nutrients. This can be a problem in marine habitats such as lakes as it can cause algal blooms.

• Fertilisers are often used in farming, sometimes these fertilisers run-off into nearby water causing an increase in nutrient levels.
• This causes phytoplankton to grow and reproduce more rapidly, resulting in algal blooms.
• This bloom of algae disrupts normal Ecosystem functioning and causes many problems.
• The algae may use up all the Oxygen in the Water, leaving none for other marine life. This results in the death of many aquatic organisms such as Fish, which need the Oxygen in the water to live.
• The bloom of Algae may also block Sunlight from photosynthetic marine plants under the water surface.
• Some algae even produce toxins that are harmful to higher forms of life. This can cause problems along the food chain and affect any animal that feeds on them.

[edit] Dangers

Virtually all types of water pollution are harmful to the health of humans and animals. Water pollution may not damage our health immediately but can be harmful after long term exposure. Different forms of pollutants affect the health of animals in different ways:

Heavy metals from industrial processes can accumulate in nearby lakes and rivers. These are toxic to marine life such as fish and shellfish, and subsequently to the humans who eat them. Heavy metals can slow development; result in birth defects and some are carcinogenic.

Industrial waste often contains many toxic compounds that damage the health of aquatic animals and those who eat them. Some of the toxins in industrial waste may only have a mild effect whereas other can be fatal. They can cause immune suppression, reproductive failure or acute poisoning. Microbial pollutants from sewage often result in infectious diseases that infect aquatic life and terrestrial life through drinking water. Microbial water pollution is a major problem in the developing world, with diseases such as Cholera and typhoid fever being the primary cause of infant mortality.

Organic matter and nutrients causes an increase in aerobic algae and depletes Oxygen from the water column. This causes the suffocation of fish and other aquatic organisms.

Sulfate particles from Acid Rain can cause harm the health of marine life in the rivers and lakes it contaminates, and can result in mortality.

Suspended particles in freshwater reduces the quality of drinking water for humans and the aquatic Environment for marine life. Suspended particles can often reduce the amount of Sunlight penetrating the water, disrupting the growth of photosynthetic plants and micro-organisms.

[edit] Prevention

If you want to help keep our waters clean, there are many things you can do to help. You can prevent water pollution of nearby rivers and lakes as well as groundwater and drinking water by following some simple guidelines in your everyday life.

Conserve water by turning off the tap when running water is not necessary. This helps prevent water shortages and reduces the amount of contaminated water that needs treatment. Be careful about what you throw down your sink or toilet. Don't throw paints, oils or other forms of litter down the drain. Use environmentally household products, such as washing powder, household cleaning agents and toiletries. Take great care not to overuse pesticides and fertilisers. This will prevent runoffs of the material into nearby water sources. By having more plants in your garden you are preventing fertiliser, pesticides and contaminated water from running off into nearby water sources. Don't throw litter into rivers, lakes or oceans. Help clean up any litter you see on beaches or in rivers and lakes, make sure it is safe to collect the litter and put it in a nearby dustbin.

[edit] Laws and conventions

There are many laws that protect the world's oceans, rivers and lakes from unnecessary water pollution. Each continent and country may differ in which laws they enforce but they aim to have the same overall positive influence.

In Europe, there have been a number laws enforced to protect the surrounding ocean from marine dumping.

• In 1989, the dumping of industrial waste was terminated in all countries in North-Western Europe, apart from the UK. Dumping was terminated in the UK in 1993.
• In 1990, the dumping of sewage sludge was terminated in all countries in North-Western Europe, apart from the UK. Dumping was terminated in the UK in 1998.
• Guidelines have been developed and are currently being reviewed regarding the dumping of polluted materials.
• Dumping of nuclear waste in European waters has been terminated since 1986.

There are a number of directives given in the European Union Environmental Legislation:

The proposed water framework directive aims to achieve a number of objectives regarding health and environmental issues:

• Enforce sufficient drinking water provisions.
• Enforce sufficient provisions if water for other economic requirements.
• Protection of the environment from water pollution.
• Provide alleviation of the adverse impacts of floods and droughts.
• The directive aims to achieve a good status for ground waters and surface waters in Europe by the year 2010.
• The urban waste water directive aims to protect surface inland waters and coastal waters from pollution by regulating the collection and treatment of urban waste water.
• The nitrate from agricultural sources directive aims to protect waters against pollution caused by nitrates, especially nitrates from agricultural sources such as fertilisers. This will enable marine and freshwaters to be protected from eutrophication.
• The drinking water directive aims to establish strict standards regarding the quality of drinking water. The directive provides parameters and analysis methods, these standards must be met to ensure safe drinking water.
• The surface water for drinking water abstraction directive and measurement and sampling of surface waters directive and information exchange decision are integrated to form a framework that deals with water protection of all waters, not just those used by humans.
• The fish water directive and shell water directive aims to protect waters from pollution that are primarily used for fishing.
• The groundwater directive aims to protect groundwater from dangerous pollutants by controlling the direct and indirect discharges of certain substances into the groundwater.
• The bathing water directive aims to keep good standards in the quality of bathing water in freshwater and coastal water areas.

[edit] Water Pollution Mitigation

[edit] Industrial treatment

Before raw sewage can be safely released back into the environment, it needs to be treated correctly in a water treatment plant. In a water treatment plant, sewage goes through a number of chambers and chemical processes to reduce the amount and toxicity of the waste.

• The sewage first goes through a primary phase. This is where some of the suspended, solid particles and inorganic material is removed by the use of filters.
• The secondary phase of the treatment involves the reduction of organic, this is done with the use of biological filters and processes that naturally degrade the organic waste material.
• The final stage of treatment is the tertiary phase; this stage must be done before the water can be reused. Almost all solid particles are removed from the water and chemical additives are supplied to get rid of any left-over impurities.

[edit] Septic tanks

Septic tanks treat Sewage at the place where it is located, rather than transporting the waste through a treatment plant or sewage system. Septic tanks are usually used to treat sewage from an individual building.

• Untreated sewage from a property flows into the septic tank and the solids are separated from the liquid.
• Solid material is separated depending on their density. Heavier particles settle at the bottom of the tank whereas lighter particles, such as soap scum, will form a layer at the top of the tank.
• Biological processes are used to help degrade the solid materials.
• The liquid then flows out of the tank into a land drainage system and the remaining solids are filtered out.

[edit] Denitrification

Denitrification is an ecological approach that can be used to prevent the leaching of nitrates in soil, this in turn stops any ground water from being contaminated with nutrients.

• Fertilisers contain nitrogen, and are often applied to crops by farmers to help plant growth and increase the yield.
• Bacteria in the Soil convert the Nitrogen in the fertilizer to nitrates, making it easier for the plants to absorb.
• Immobilization is a process where the nitrates become part of the soil organic matter.
• When Oxygen levels are low, another form of bacteria then turns the nitrates into gases such as nitrogen, nitrous oxide and nitrogen dioxide.
• The conversion of these nitrates into gas is called denitrification. This prevents nitrates from leaching into the soil and contaminating groundwater.

[edit] Ozone wastewater treatment

Ozone wastewater treatment is a method that is increasing in popularity. An ozone generator is used to break down pollutants in the water source.

The generators convert oxygen into ozone by using ultraviolet radiation or by an electric discharge field.

• Ozone is a very reactive gas that can oxidise bacteria, moulds, organic material and other pollutants found in water.
• Using ozone to treat wastewater has many benefits:
• Kills Bacteria effectively.
• Oxidises substances such as iron and sulphur so that they can be filtered out of the solution.
• There are no nasty odours or residues produced from the treatment.
• Ozone converts back into oxygen quickly, and leaves no trace once it has been used.

The disadvantages of using ozone as a treatment for wastewater are:

• The treatment requires energy in the form of Electricity; this can cost money and cannot work when the power is lost.
• The treatment cannot remove dissolved minerals and salts.
• Ozone treatment can sometimes produce by-products such as bromate that can harm human health if they are not controlled.

[edit] Related Topics

• Pollution
• Pollutants