Earth : a watery planet Water: the bloodstream of the biosphere. Water: a renewable, finite and vulnerable natural resource Water: uses, uniqueness, water cycles Water: definition, characteristics, sources, composition and global distribution Molecular structure and characteristics. Physical, chemical and biological properties Water crisis and remedial measures
The earth is theonly planet with Evidences:water which 1.water occurs on itssupports life. surface as liquid, iceThe planet earth is and gas.also called the„blue planet‟ due 2.ocean covers 71% ofto the presenceabundant water the globe.on its surface. 3.Freshwater is less than 1%. 4.Ice sheets cover polar region. 5.Glacier‟s are found in higher mountains.
Water is one of the prime elements responsible for life on earth. Water sustains life and maintains ecological balance. Water is the essential component of global life support system.
Water is naturally recycled inthe hydrological cycle.• The total amount of water on earth is 1.4 billion cubic kilometers , but only 41,000 km3 circulates in the hydrological cycle.
Water is a simple inorganic molecule•A water molecule has one oxygen and two hydrogen atoms.The trade of „virtual‟ water (Allen 1994)•Water is traded in the form of its products.•The products include grains, timber, meat, fodder, fruits, flowers etc.Water is a vital element for human life•The need for water rise along with population growth, urbanization and industrialization.•Drought, floods and lack of fresh water may cause global instability and conflict.
Water is Water is non- Water is finite Water is unique Water is substitutable preciousessential •All water • Water is neither created nor •It costs money• There is no life •There is no comes from destroyed , it only without water. alternative for the rainfall. moves from to• There is no water. •The amount of place to place extract, treat, human activity rainfall that and changes in process and that does not falls on the quality. distribute. depend on continents is water. finite.
Water is the only natural substance that exists in 3 physical states: solid, liquid and gas. For almost every other compound the solid state is denser than the liquid state. So the solid would sink to the bottom of the liquid but ice floats on water. Water vapour is responsible for more than half of the earth‟s greenhouse warming.
Domestic use Public use Agricultural useDrinking, Cooking, irrigation of parks, Fire Production of food grains,Bathing, washing fighting, Filling pools fruits and vegetablesRecreational use Industrial use Environmental use used for cooling and Habitat for aquatics Water sports creating steam &wildlife
As a nourisher of plant &animal life.a bearer of food.a prime element ofindustrial processesa medium for transportation.
Water is a binarycompound that is acolorless, tasteless,odourless liquid atroom temperature.
Humanorganisms Humans -60% beings Most organisms Brain -90% - 60-90% Blood -83% Plant seeds -20% Muscle – 75% Jelly fish -99% Bone – 22%
97.200% 00.001% air sea water moisture 02.014% ice00.005% soil caps and moisture glaciers 00.009% 00.600% surface ground water water
Surface water: Ground water: river, lakes, pore space soils, wetlands rocks
Solids Liquids Gaseswhen water becomes very cold in liquidand it freezes form, water in vapor formfrom a liquid takes the water has no to a solid. shape of its definite size. It has a containerdefinite formand shape.
Ocean Water:salt water is found in the oceans and seas.Fresh Surface Water:fresh water is found in rivers, streams, lakes andponds.Ground water:Ground water is stored in underground aquifers. Waterin aquifer remains there for an average of 1,400 years!
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.
The water molecule has a tetrahedral structure with oxygen at its center. The two bonds with hydrogen are directed toward two corners of the tetrahedron. The unshared electrons occupy the remaining two corners.
Oxygen is negatively charged with respect to the two hydrogens in the water molecule. Although the water molecule as a whole is electrically neutral, the asymmetric distribution of electrons results in one side being positively charged with respect to the other.
Water has two different poles (dipole), like that of a magnet. The water molecule creates a region of positive charge and region of negative charge. when electrons are shared between oxygen and hydrogens, they are closer to the oxygen than the hydrogens. Therefore the oxygen has a greater negative charge due to the greater electron density. The hydrogens which are not very electronegative will have a greater positive charge due to the lack of electron density.
Water can dissolvesalts, acids, sugars, The polar moleculesas well as alkalis have the property ofand gases. Most cell attracting each other.components As a result waterincluding proteins,polysaccharides molecules aggregateand DNA dissolve inwater making it the together.basis of life. The polarity makes water a universal solvent.
Cohesion is the force of attraction between molecules of the same substance. The hydrogen bonding between molecules makes water more sticky leading to a higher degree of cohesion and adhesion. Cohesion due to hydrogen bonding contributes to the formation of waves and other water movements that occur in lakes.
Boiling point 99.98 0 C Freezing Point 0.0 0CWater High Specific Heat capacity Latent Heat of fusion 334 kJ/kg Latent Heat of Vaporization 2270 kJ/kg
Density at 4 0C Surface tension Viscosity & tensileWater High strength Dielectric constant Transmission of visible light
Water scatters and absorbs light. Water absorbs light at the red end of the spectrum more easily than at the blue end. Water conducts sound waves. Water exerts pressure (i.e. Hydrostatic pressure= weight of the water). Water moves from the area of higher solute concentration to the area of lower solute concentration until equilibrium is reached.
Water is a source of hydrogen and oxygen for chemical reactions. Water is a highly reactive molecule which can form hydrogen bonds with other molecules. Water molecule each possess a strongly nucleophilic oxygen atom that enables many of life‟s reactions as well as ionizing to produce reactive hydrogen and hydroxide ions. Water combines with salts to form hydrates and reacts with metal oxides to form acids.
There are TWO overlapping water cycles in nature. 1.Natural water cycle • Does not involve life 2. Biological water cycle • Involve life (Biological cycling)
Evaporation – the process by which water changes from liquid to gaseous state. condensation 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 vaporEvaporation Precipitation thro‟ leaves. Accumulation – water gets collected in oceans , seas and lakes.
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.
This cycle refers to volume of water content in the living organisms. 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.
Aquatic plants and animals absorb water from the medium. Trees absorb water by roots from the soil.Water returned to the environment by Plants loose water by bacterial transpiration thro‟ decomposition of leaves.dead organic matter. Animals loose water by sweating and elimination.
Water is one of the most essential elements to good health. Transports nutrients and oxygen to cells Aids metabolic break down of proteins and carbohydrates. Helps digestion and absorption of food. Protects body organs and tissues. Regulates body temperature. Facilitates the excretion of wastes. Lubricates joints and muscle tissues. Moistens tissues of mouth, eyes and nose. Serves as a natural air conditioning system.
A solvent As A coolantsupport Biological roles A Anreagent insulator A lubricant
Human consumption- (drinking and cooking)Food production (irrigation) Personal hygiene Sanitation Industrial production Energy generation Economic development Environmental protection
Soil water serves as a solvent and carrier of food nutrients for plant growth. Soil water regulates soil temperature. Soil water helps in chemical and biological activities of soil. Crop yield is proportional to the availability of water. Soil forming processes depend upon water.
Water is the most abundant constituent of plant cells. Leaves consist of 55-85% water of their fresh weight. Water is fundamental to photosynthesis and respiration. Water maintains turgidity in plants which helps to stand erect.
All life is aquatic • Life originates from water a billion years ago. Major constituent • The cells are filled with water. • The tissues are bathed in watery extra cellular Of life fluids. Medium for • Three important types of reactions in water biochemical are precipitation, acid-base, and oxidation- reactions reduction reactions.Protect and stabilize • Protects membrane proteins from de-naturation.plasma membranes • Stabilize lipid-protein-lipid cell surface by & macromolecules hydrophobic interaction
• Permanent habitat for many species ofHabitat for fish (8,500 species) animals • Temporary home for amphibians and reptiles (4,200 species) Blood • High surface tension of water allows clotting efficient blood clotting.Conduction • High electrical conductivity of water of nerve permits greater speed of impulse conduction. impulse
Water is used in the direct production of agricultural and industrial goods. Water is used to produce energy- hydroelectric power. Water is used in the drilling, mining and processing of fossil fuels such as oil and coal. Water is used to cool processors and material used in nuclear power plants.
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.
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.
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.
Workshop on “ Value WaterWater and Use water sustainablypopulation Develop suitable institutions todynamics” manage water(IUCN World Collect and disseminateConservation informationcongress in Maintain a social and culturalMontreal 1996) perspective Ensure equitable access to water Use appropriate technology Try to Solve causes, not symptoms -but accept practical solutions Take an ecosystem approach Work as multidisciplinary teams.
Dr.B.Victor is a highly experienced professor, recently retired(2008) from the reputed educational institution- St. Xavier‟ s College, Palayamkottai, India-627001. He was the dean of sciences, IQAC coordinator and assistant controller of examinations. He has more than 32 years of teaching and research experience He has published 5 research articles in international journals and 32 in reputed Indian journals and guided 12 PhDs. Send your comments to : email@example.com