ENV Lecture 11-12 PDF

ENVIRONMENT The surroundings or conditions in which living organism is present is called environment. ENVIRONMENTAL SEGMENTS Four segments- 1)Atmosphere- above 500 – 1200 Km from surface 2)Hydrosphere- water content above and below surface 3)Lithosphere- minerals and soil 4)Bi...

ENVIRONMENT The surroundings or conditions in which living organism is present is called environment. ENVIRONMENTAL SEGMENTS Four segments- 1)Atmosphere- above 500 – 1200 Km from surface 2)Hydrosphere- water content above and below surface 3)Lithosphere- minerals and soil 4)Biosphere- covers all living organism Structure of the earth  Major elements in order of the decreasing concentration in different sectors Atmosphere: N, O Ocean: O, H (Cl, Na, Mg, S) Sedimentary rocks: O, Si, Al, Fe, Ca, K, Mg, C, Na Granitic igneous rock: O, Si, Al, K, Na, Ca, Fe, Mg Baseltic igneous rock: O, Si, Al, Fe, Ca, Mg Mantle: O, Si, Mg, Fe  Pollutant: A substance present in nature and is greater than natural abundance due to anthropogenic activity and sometimes also natural, which ultimately has a harmful effect on the environment, living organisms and mankind. For example lead (Pb), SO2, CO2. Pollutants may come from two source. 1.Anthropogenic activity (man made activity) 2.Natural activity Environmental Pollution: Environmental pollution is defined as any undesirable change in physical, chemical of biological characteristics of our land, air or water that may harmfully affect human life or that of other desirable species, industrial process, living conditions and cultural asset or that may waste or deteriorate our natural resources. Contaminants: A material does not exist in nature but introduced by human activity into environment. For example, Cl2 gas escaped from a derailed railway tank in Florida 1978 and killed 8 people. This gas does not exist in the atmosphere. Receptor: The medium which is affected by a pollutant. For example man is the receptor of photochemical smog causing irritation of the eyes and respiratory tract. Sink: The medium which retains and interacts with a long-lived pollutant. For example- A marble wall act as a sink for atmospheric H2SO4 and ultimately get damaged. H2SO4 + CaCO3 CaSO4 + H2O + CO2 The oceans are the sink for atmospheric CO2  Types of environmental pollution: 1. Water pollution 2. Air pollution 3. Thermal pollution 4. Light pollution 5. Noise pollution 6. Land pollution  Water pollution: Any human activities that impairs the use of water as resources is called water pollution. Water Pollutants ▪ Organic ▪ Inorganic ▪ Sediments ▪ Radioactive materials ▪ Thermal pollutants  Sources of Water Pollutants Industrial wastes Sewage and other oxygen-demanding wastes Infectious or disease causing agents Plant nutrients Synthetic organic chemicals Inorganic minerals and chemical compounds Suspended solids or sediments Radioactive substances like I-131, Sr-90, Ra-226 Thermal discharges Oil Detergents, etc ATMOSPHERIC CHEMISTRY Or, some solid particle or liquid droplets which are suspended in atmosphere are collectively called aerosol  Air Pollution Air pollution is the introduction of particulates, biological molecules, or other harmful substances into Earth's atmosphere, causing diseases, allergies, death to humans, damage to other living organisms such as animals and food crops, or the natural or built environment.  Types of Air Pollution Outdoor Air Pollution o Smog o Particulates o Acid rain o Greenhouse Gases Indoor Air Pollution  Causes ▪ Natural Sources - smoke that comes from wildfire, volcanoes, methane, dust ▪ Human dust - power plants and automobile fumes, burning wood, stoves, fireplaces and furnaces Six major air pollutants Carbon monoxide (CO) Ozone (O3) Nitrogen dioxide (NO2) Sulfur oxides (SOx) Carbon dioxide (CO2) Lead (Pb)  Effects Human Effects e.g. diseases Environmental Acid rain Effects Eutrophication Haze Wildlife Ozone depletion Crop and forest damage Global Climate change  Step 1: Formation of O atom by UV photolysis of O2 hv O2 2O Step 2: Formation of O3 M+ O + O2 O3 + M M = third body (e.g. NOx)  Ozone depletion Due to anthropogenic activity human produce some gas which react with ozone in stratosphere and thereby the concentration of ozone in the stratosphere decreases, which is known as ozone depletion. Tropospheric Ozone Depletion  Stratospheric Ozone Depletion Chapman cycle CFCs Catalytic Cycle I Cl. - Catalytic Cycle II  Greenhouse Effect The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without its atmosphere. ❑ Carbon dioxide (CO2) and other greenhouse gases act like a blanket, absorbing IR radiation and preventing it from escaping into outer space. The net effect is the gradual heating of Earth's atmosphere and surface, a process known as global warming.