Contents of the lectureWaterEarths water supply & distributionHydrologic cyclePollution of waterSources of water pollutionTypes of water pollutionTypes of water pollutantsAcid rainWater borne diseases

Water is essential to life on earth.*

Three forms of Water.Solids: When water becomes very cold and freezes it will change from a liquid to a solid. It has a definite form and shape.Liquids: When water takes the shape of its container it is in a liquid form.Gases: When water is seen in a vapor form and has no definite size or shape it is in a gas form.

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The earth's water supply

97.2% of the Earth's water supply is salt water. Only 2.8% is fresh water! *

*97% salt water in the oceans 2% ice caps and glaciers 0.6% groundwater 0.009% surface water 0.005% soil moisture 0.001% atmospheric moisture

Distribution of waterOcean Water: The vast majority of water on the planet is the salt water in the oceans and seas.

Fresh Water: This is the fresh water in rivers, streams, lakes, ponds and similar bodies of water.

Groundwater: The majority of the planet's liquid freshwater is stored in underground aquifers. Water that enters an aquifer remains there for an average of 1,400 years!*

Water : A precious Natural ResourceWe use water for drinking, irrigation, industrial purposes and energy production. Water useagriculture and energy production - 80%industry and public use - 20%

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*It describes the continuous movement of water on, above or below the surface of the earthPowered by energy from the sunHydrologic cycle purifies water

Hydrologic cycle - water cycle

Basic steps of water cycle areEvaporationCondensationPrecipitationTranspirationRunoffInfiltration*

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Where do Water pollutants come from?Point Sources A single definable source of the pollution, e.g. a factory, a sewage plant, etc. Point-source pollution is usually monitored and regulated.

Non-point sources No single source, but a wide range of sources, e.g. runoff from urban areas, or farmland. Non-point sources are much more difficult to monitor and control.

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Pollution of Water Surface water pollutionGroundwater pollutionMicrobiological pollutionOxygen depletion pollutionNutrients pollutionSuspended matter pollutionChemical pollution*

Pollution of Water Surface water pollution

Surface water includes natural water found on the earth's surface, like rivers, lakes, lagoons and oceans. Hazardous substances coming into contact with this surface water, dissolving or mixing physically with the water can be called surface water pollution. E.g.plastic bottles, shopping bags and trash from human consumption*

Pollution of Water 2. Groundwater pollution

When humans apply pesticides and chemicals to soils, they are washed deep into the ground by rain water. This gets to underground water, causing pollution underground. This means when we dig wells and bore holes to get water from underground, it needs to be checked for ground water pollution.*

Pollution of Water 3. Microbiological pollution

In many communities in the world, people drink untreated water (straight from a river or stream). Sometimes there is natural pollution caused by micro-organisms like viruses, bacteria and protozoa. This natural pollution can cause fishes and other water life to die. They can also cause serious illness to humans who drink from such waters.*

Pollution of Water 4. Oxygen depletion pollution

Water bodies have micro-organisms. These include aerobic and anaerobic organisms. When to much biodegradable matter (things that easily decay) end up in water, it encourages more microorganism growth, and they use up more oxygen in the water. If oxygen is depleted, aerobic organisms die, and anaerobic organism grow more to produce harmful toxins such as ammonia and sulfides.*

Pollution of Water 5. Nutrients pollution

Found in waste water and fertilizers. They can cause excess vegetation in water such as algae and weeds which use up oxygen in water hurting marine life.*

Pollution of Water 6. Suspended matter pollution

It occurs when pollutants enter the water and do not mix with water molecules. These suspended matter forms fine silt in water.*

Pollution of Water 7. Chemical pollution

There is a lot of chemical run off from factories into the water bodies which includes metals, solvents, pesticides from industries. They add poison to wildlife in water.*

Non-persistent (degradable)water pollutantsThese compounds can be broken down by chemical reactions or by natural bacteria into simple substances such as carbon dioxide and nitrogen. If the pollution load is high, this process can lead to low oxygen levels. E.g. Domestic sewage, fertilizers and some industrial wastes

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Persistent Water pollutantsThis is the most rapidly growing type of pollution This includes substances that degrade very slowly or cannot be broken down at all; They may remain in the aquatic environment for years or longer periods of time. some pesticides, petroleum products, radioactive materials and metals.

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Water borne diseasesDiseases caused by the ingestion of water contaminated with pathogenic bacteria, viruses, or parasites include:cholera typhoid DysenteryOther diarrheal diseases

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Remedial measuresLocate the point sources of pollution. Work against acid rain. Educate your community. Ensure sustainable sewage treatment. Watch out for toxins. Be careful what you throw away. Think globally, act locally. *

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