Lecture 7 - 2/1/2011 Announcements Earth’s Environmental...

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Unformatted text preview: 2/1/2011 Announcements Earth’s Environmental Systems II & Atmospheric Environment ENV200H1S – February 1 2011 Tutorial #2 – Fair Share of Resources (Tragedy of the Commons) start next week Worksheet posted Calculate ecological footprint Read 3 articles & answer questions: Go forth, multiply and fill the provinces Does helping the planet hurt the poor? No, if the West makes sacrifices Does helping the planet hurt the poor? Yes, if we listen to green extremists 1 2 Outline Biogeochemical Cycles Earth’s Environmental Systems Biogeochemical cycles Atmospheric Environment, p. 340-348 340 El Nino Southern Oscillation (ENSO), p. 322322-324 Thursday – Global Climate Change, p. 368368-382; Ozone Depletion, 383-386 383- Matter cycles through ecosystems Carbon Hydrologic (water) Nitrogen Phosphorus 3 Carbon Cycle 4 Carbon Cycle Essential component for life Gas (CO2) in atmosphere Several forms in ocean Can take a long time—think fossil fuels time— Photosynthesis CO2 Cellular respiration Sugar CO2 5 6 1 2/1/2011 Nitrogen Cycle Hydrologic Cycle Ocean Atmosphere Land Ocean Proteins, DNA Atmosphere is 78% N2 Five steps Nitrogen fixation Nitrification Assimilation Ammonification Denitrification 7 8 Nitrogen Cycle Nitrogen Fixation Specialized bacteria Split atmospheric nitrogen and combine it with hydrogen 9 10 Nitrogen Cycle Phosphorus Cycle take home messages Human activites have significantly influenced nitrogen cycle In early 20th C, chemical advances allowed almost pp almost unlimited supplies by converting atmospheric nitrogen to ammonia (a more biologically useable form Projected that amount of nitrogen deposition on Earth’s surface will double within next 25 years. Eutrophication, water quality, smog, acid Eutrophication, rain, greenhouse gases 11 No atmospheric component Phosphates used in DNA and ATP (chemical (chemical energy) Phosphates move through the food chain Land Organism Organism Land 12 2 2/1/2011 Phosphorus Cycle Phosphorus Cycle Patchy distribution When trapped in lithosphere may stay there for extended periods, e.g. Ocean floor floor for millions of years Traditionally a limiting factor that can prevent growth, distribution or abundance Overabundance can have many interconnected impacts 13 The Atmosphere 14 The Atmosphere Gaseous envelope surrounding Earth Mostly oxygen & nitrogen (99%) Four layers Troposphere Stratosphere Mesosphere Thermosphere 15 16 Atmospheric Temperature Changes The Atmosphere 17 18 3 2/1/2011 19 The Atmosphere What’s In Our Atmosphere Nitrogen Oxygen Argon Argon Carbon dioxide Other Gases 20 Ecosystem services Protects Earth from UV radiation Allows visible light and some infrared 78% 21% 0.93% 0.04% 0.03% to penetrate We depend on the atmosphere Oxygen balance 21 From our sun’s energy output and our distance from it you would predict that Earth should have a temperature of -18o C: Yet, Earth’s global average temperature is about + 15o C What factors account for the ‘extra’ 33oC? Nature of EMR and its various fates Composition of the atmosphere, hydrosphere, lithosphere 23 22 Solar Radiation and Atmospheric Circulation Electromagnetic spectrum Entire range of electromagnetic radiation includes gamma, x-ray, ultraviolet, visible, xinfrared, microwave, and radio Gamma, x-rays and most UV rays are absorbed xby the stratosphere Plants use portions of visible light for photosynthesis 24 4 2/1/2011 The different wavelengths comprising the EMR spectrum that comes from the sun Solar Radiation Visible light passes through atmosphere undiminished. Ultraviolet light is absorbed by ozone in the stratosphere. Infrared radiation is absorbed by carbon dioxide and water water in the troposphere. 1 mm cell phones High energy, short λ Low energy, long λ 25 26 Behaviours of EMR reflection When a wavelength of EMR moves out of the vacuum of space and enters the atmosphere, a number of things could happen: (1) nothing (transmission) (2) reflected (off dust, clouds, etc.) etc (3) absorbed (by water vapour, oxygen, the oceans, land masses, etc.) etc transmission 27 Numerous substances can absorb EMR land masses water (significant given that 70% of Earth is ocean) various gases in the atmosphere (O2, H2O, CO2) th (O CO The physicochemical properties of each of these substances determines which λ are absorbed. This is particularly true of different gases in the atmosphere which means the surface of the Earth is exposed to a substantially modified spectrum of EMR when compared to what came in at the top of the atmosphere (from the sun). 29 Absorption of high energy λ = 28 rere-emission of lower energy λ + heat Earth’s Energy Budget 30 5 2/1/2011 The Seasons The Sun & Latitude Inclination on its axis determines Earth’s Sun does not seasons reach all places uniformly: why? Temperature varies locally N. and S. hemispheres are opposite 31 32 6 ...
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This note was uploaded on 08/10/2011 for the course ENV 200 taught by Professor Karening during the Spring '11 term at University of Toronto.

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