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Human impact on global water


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Water is facing a crisis today.
Water scarcity affects all social and economic sectors.
Water footprint measures the consumption and contamination of freshwater resources.

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Human impact on global water

  1. 1. 22 March is World Water Day Presented by Dr. B. Victor., Ph. DEmail : Blog:
  2. 2.  Introduction  Chemical structure Life – supporting  Global water cycle functions of water.  Kinds and sources of Water is vital to human water pollution life  Health impacts of water Global water issues pollution Global distribution of  Water footprint water  Water pollution episodes Properties of water  Remedial measures
  3. 3.  The earth is the only planet with water. The planet earth is also called the ‘blue planet’ due to the presence abundant water on its surface. The earth is the only planet that supports life.Evidences:1.water occurs on its surface as liquid, ice and gas.2.ocean covers 71% of the globe.3.Freshwater cover les than 1%.4.Ice sheets cover polar region.5.Glacier’s are found in higher mountains.
  4. 4.  Water covers approx.71 % of the planet earth and constitutes 60-70 % of the living world. The existence of life on earth is not possible without water. The environmental system within which we live is dependent on water.
  5. 5.  Human consumption- (drinking and cooking) Food production (irrigation) Personal hygiene Sanitation Industrial production Energy generation Economic development Environmental protection.
  6. 6.  An average adult human body contains 42 liters of water. Water is required for digestion and absorption of food. Water transfers oxygen and nutrients to the cells. Water carries metabolic wastes. Water act as a natural cooling system.
  7. 7.  Water shortage - levels of available water do not meet minimum requirements. Water scarcity – the relationship between demand for water and its availability. Water stress – decline in water quality. Water security – access to adequate quantity and safe quality.
  8. 8.  Water is facing a crisis today. Water scarcity affects all social and economic sectors. There are concerns that water will increasingly be the cause of violence and even war. Water is recognized as one of the key limiting resources of this millennium.
  9. 9.  Approx. 700 million people in 43 countries suffer as a result of water scarcity. Nearly 1 billion people lack safe drinking water. Half of the world’s 500 major rivers are polluted. 75% of India’s lakes and rivers are too polluted for safe use.
  10. 10.  The total amount of water on the earth is about 326 million cubic miles of water. The needs for water rise along with population growth, urbanization and increases in the number of households and industrial uses.
  11. 11. 97.200% sea water 02.014% ice caps and glaciers 00.600% ground water 00.009% surface water 00.005% soil moisture 00.001% air moisture
  12. 12.  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: in liquid form, water takes the shape of its container. Gases: in vapor form water has no definite size.
  13. 13.  Ocean Water: salt water is found in the oceans and seas. Fresh Surface Water: fresh water is found in rivers, streams, lakes and ponds. Ground water: Ground water is stored in underground aquifers. Water in aquifer remains there for an average of 1,400 years!
  14. 14.  A water molecule has one oxygen atom and two hydrogen atoms. The two hydrogen atoms bound to one oxygen atom to form a ‘V’ shape at an angle of 105 degree. The length of the bond between the oxygen and the hydrogen is 95.84 pm (picometre). The chemical formula for water is H2O, meaning two hydrogen atoms covalently bonded to one oxygen atom.
  15. 15.  Water is colorless, tasteless and odorless. Water is a great solvent. Water exists as a liquid, in rivers and seas, a solid, as snow and ice, and as a gas, as clouds or steam.  Water can absorb a large amount heat(high specific heat capacity). Water can stick together into beads and drops( surface tension). Water flows and erodes the surface of the earth.
  16. 16.  There are TWO overlapping water cycles in nature.
  17. 17.  Water evaporates from water bodies like seas, and oceans, lakes and rivers. Water vapor cools and condenses in the clouds. Water precipitates in the form of rain and snow which fall on the soil. Runoff and accumulation forms fresh water lakes, streams, ponds and groundwater.
  18. 18.  Evaporation – the process by which water changes from liquid to gaseous state. Condensation – the process by which a gas changes to a liquid. Precipitation – clouds in the air drop rain on land. Transpiration – the process by which plants release water vapor thro’ leaves. Accumulation – water gets collected in oceans , seas and lakes.
  19. 19.  This cycle refers to volume of water content in the body of an organism. Aquatic plants and freshwater animals absorb water from the surrounding medium by osmosis. Trees absorb water from the moist soil thro’ roots. Land animals receive water by feeding and drinking. Plants loose water by transpiration thro’ leaves. Animals loose water by sweating and elimination. After death water returned to the environment by bacterial decomposition.
  20. 20.  Pure water = 7.0 pH Rain from unpolluted atmosphere = 6.0 pH Natural rain water = 5.6 pH Acidic rain water = 4.5 pH Rain near urban areas = 4.0 pH Rain from fog clouds = 1.7 pH
  21. 21.  Surface water pollution - pollution of lakes, rivers and oceans Groundwater pollution - pollution of aquifers below soil. Microbial pollution – pollution by bacteria, viruses, protozoa and parasitic worms. Oxygen depletion pollution – pollution by biodegradable organics. Nutrient pollution – pollution by plant nutrients (nitrates, phosphates) Suspended matter pollution – pollution by soil, silt Chemical pollution - pollution by pesticides, fertilizers, industrial solvents, oil Thermal pollution- pollution by warm water, waste heat
  22. 22.  Point Sources – A single definable source of the pollution, e.g. a factory, a sewage plant, etc.- pollution is easy to monitor and control, Non-point sources – No one single source, but a wide range of sources, e.g. runoff from urban areas, or farmland.-Pollution is more difficult to monitor and control.
  23. 23.  Non-point sources  Point Sources
  24. 24.  Non-persistent pollutants can be broken down by natural chemical reactions or by natural bacteria into simple, non- polluting substances such as carbon dioxide and nitrogen. e.g. wood, paper, biological wastes More load of degradable pollutants can lead to low oxygen levels and eutrophication. But this damage is reversible.
  25. 25.  Organic chemical substances are persistent that degrade very slowly or cannot be broken down at all. They may remain in the aquatic environment for longer periods of time. The damage is irreversible and is the most rapidly growing type of pollution.
  26. 26.  Pesticides - DDT, dieldrin Leachate components from landfill sites (municipal, industrial) Petroleum and petroleum products PCBs, dioxins, polycyclic aromatic hydrocarbons (PAHs) Radioactive materials- strontium-90, cesium-137, radium-226, and uranium Metals - lead, mercury, cadmium
  27. 27.  Industries effluents contain heavy metals , resin pellets, organic toxins, oils, nutrients, and solids.
  28. 28. Impact of Microbial water pollution No. of people lack access to safe drinking water = Over 1 billion. No. of people lack adequate sanitation = 2.6 billion . This has led to widespread microbial contamination of drinking water. Deaths due to water-associated infectious diseases =up to 3.2 million people per year. (approx. 6% of all deaths globally). Deaths due to diseases caused by inadequate water, sanitation, and hygiene = 1.8 million people.
  29. 29.  excessive amounts of plant nutrients=P,N,C. Excessive growth or ‘blooms of algae’ Algal blooms leads to oxygen depletion. Hypoxia leads to mass fish kills. Degradation of water and habitat quality.
  30. 30.  Drought causes more damage and suffering than any other natural disaster. 80 countries experience droughts lasting more than 1 year. According to the UN, almost 500 million people, in 31 countries (~40% of the world’s population) experience chronic water scarcity. Water scarcity is already a problem in many countries.
  31. 31.   50% of the world’s population lives on or within 160 miles of shore. Fourteen billion pounds of garbage, mostly plastic, is dumped into the ocean every year. For every 1 million tons of oil that is shipped, about 1 ton is spilled. More oil is seeped into the ocean each year as a result of leaking cars and other non-point sources
  32. 32.  Asian rivers are the most polluted in the world. River Ganges in India is one of the most polluted rivers in the world. Approximately 46% of the lakes in America are too polluted for fishing, aquatic life, or swimming.
  33. 33.  The amount of plastic waste has been increasing about 10% each year for the past 20 years. Over 1 million seabirds are killed by plastic waste per year. Over 100,000 sea mammals and countless fish are killed per year due to pollution.
  34. 34. “Water contributes much to health” - Hippocrates ( 460 – 377 B.C )
  35. 35.  Neurotoxins – destroying nervous tissue. Carcinogens – inducing cancers Mutagens – altering genetic characteristics Teratogens – causing non-hereditary birth defects.
  36. 36.  Pesticides - damage nervous system and also cause cancer. Lead – affects central nervous system . Fluorides – damage teeth and the skeleton. Nitrates – cause blue – baby syndrome in infants. Petrochemicals – cause cancer. Arsenic – damage liver and nervous system, skin cancer. Heavy metals – damage nervous system and kidneys.
  37. 37. Toxicity- acute / chronic – damages aquatic / human lifeChanges in Sub-lethal toxicityWater chemistry Endocrine disruption / Changes in biodiversity Effects of water Acidity/alkalinityEutrophication pollution Changes pH regime Altered water Spread of microbial temperature diseases Deoxygenation- Lack of O2 in water
  38. 38. Diseases caused by the ingestion ofcontaminated water.
  39. 39. Water – scarce Water- related vector(water –washed) diseases diseases Vectors : Mosquitoes, tsetse flies Trachoma  Malaria Leprosy  Yellow fever Tuberculosis  Dengue fever Whooping cough  Sleeping sickness Tetanus  filariasis diphtheria
  40. 40.  Water – based diseases-skin contact with aquatic intermediate host in water. Guinea worm infections Schistosomiasis.
  41. 41.  Each year, there are about 250 million cases of water- related diseases. It is estimated that at least 1.5 million children under the age of 12 die annually due to water pollution. 1.4 million people die each year in India from water pollution.
  42. 42.  Water footprint measures the consumption and contamination of freshwater resources. It was first introduced by Hoekstra in 2002 to provide a consumption- based indicator of water use. Water footprint differs around the world and depends on climate, soil types, irrigation methods and crop genetics. 
  43. 43.  Your water footprint extends beyond the average 80-100 gallons of water you use everyday. A product water footprint is the total volume of freshwater consumed, directly and indirectly, to produce a product. 
  44. 44.  Each person daily needs 20 to 50 liters for drinking and hygiene. Since 1970, global demand for water has risen nearly 2.4 % per annum. 20 developing countries are classified as ‘water scarce’.
  45. 45.  Locate 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. Use water efficiently. Spread the word.
  46. 46. “ Water has the power to move millions ofpeople – let it move us in the direction ofpeace”. -Mikhail Gorbachev, president, Green Cross International.
  47. 47.  Dr.B.Victor is a highly experienced postgraduate professor from the reputed educational institution- St. Xavier’ s College(autonomous), Palayamkottai, India-627001. He had been the dean of sciences and assistant controller of examinations. He has more than 32 years of teaching and research experience He has taught a diversity of courses ranging from pre- university to post graduate classes. He retired from service on 2008. Send your comments to :