ees350 atmos consitutents

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Information about ees350 atmos consitutents
Education

Published on April 7, 2008

Author: Samantha

Source: authorstream.com

Structure of this course Part I:  Structure of this course Part I Make up of atmosphere The effect of sun and energy balance Some fundamentals of how atmosphere operates Pressure Adiabatic processes Structure of this course Part II:  Structure of this course Part II Weather Macroscale Mesoscale Structure of this course Part III:  Structure of this course Part III Stella - Analyzing complex environmental systems Natural major elemental cycles Air pollution and the biosphere Types of air pollution Structure of this course Part IV:  Structure of this course Part IV Actual field monitoring study on NOx and O3 pollution Trained to calibrate equipment Trained to use equipment This will be a team effort One report required from team Requirements of the course:  Requirements of the course Attend class Read the assignments Term paper with oral presentation Stella assignment Field study Course grading:  Course grading Mid-term exam 100 points Final Exam 150 points Written term paper 100 points Oral presentation 50 points Stella assignment 50 points Field study 150 points Total points 600 points Environmental Science:  Environmental Science What is it? Environmental Science:  Environmental Science What is Science? Systematized knowledge derived from the formulation of a problem, collection of data through observation and through experimentation What is social science? The study principally of people and how they live and interact together Environmental Science:  Environmental Science Environmental science encompasses all the fields of natural science (biology, chemistry, geology, physics including organic chemistry, nuclear physics etc) and their application to study and understanding the natural world around us as well humans impact and influences on that world. The atmosphere:  The atmosphere Formation of the Earth:  Formation of the Earth Made up of elements that cooled and condensed into a planet Certain elements readily condensed (solidified) Others were more volatile (less condensable) Make up of the Earth:  Make up of the Earth Mg Si Fe Al Ca Na Ni Cr Mn All came from gas phase of the cooling Sun’s nebula These are the condensable elements Make up of the Earth:  Make up of the Earth H He O C Ne N S Ar P More volatile elements How did they get into the earth’s rock like structure? Likely formed into less volatile compounds in the “rocks” Been slowly out - gassing ever since The early Earth:  The early Earth Earth’s core was very hot Heated the whole planet Liquefied the whole Earth Oceans of magma! The early Earth:  The early Earth Now the Earth started to cool by convection Dense compounds (& high melt point) sank to the center The core is 34% Fe and 2 % Ni Low density and low melting point (relatively speaking) stayed near the surface Al, Si, Na, Ca Dense compounds sank to center Hot! Low density to surface Cool! The early Earth:  The early Earth The surface now cooled enough to solidify The core partly remained liquid Temp = 4300 C Density = 13,000 kg/m3 Pressure = 3,850,000 Bars Cool surface Partly liquid outer core Hot! Inner core solid Earth’s 1st Atmosphere:  Earth’s 1st Atmosphere Likely was high in H and He Why? Most abundant elements in Sun’s nebula A much stronger solar wind (than now) stripped this atmosphere away from the Earth Other Planets as well! Earth’s 2nd Atmosphere:  Earth’s 2nd Atmosphere Sometimes called the Pre-biotic Atmosphere Resulted from out gassing of earth’s mantle What oxygen was present was there in the “OH-” form (hydroxyl form) Reacted with H2, CH4, NH3 and H2S Formed H2O, CO, CO2, NO2 and SO2 Earth’s 2nd Atmosphere:  Earth’s 2nd Atmosphere As mantle rock rose to surface these gasses were ejected into the atmosphere by : Volcanoes Fumaroles Steam wells Geysers Earth’s 2nd Atmosphere:  Earth’s 2nd Atmosphere As the cooling progressed these gasses remained in the atmosphere Now we have an atmosphere made up of: H2S,CO,CO2,NO2 and SO2 Note:: No free oxygen in this atmosphere! A witches brew! Earth’s 2nd Atmosphere:  Earth’s 2nd Atmosphere Out gassed water condensed to form the primordial oceans Have calculated that all the waters in the Earth’s oceans and atmosphere could be accounted for by H2O released by Earth’s volcanoes etc over geologic time Earth’s 3rd Atmosphere:  Earth’s 3rd Atmosphere This “final” atmosphere on Earth was shaped by biology! Life changed the Earth’s 2nd atmosphere A contradiction Life could not exist without the current atmosphere This current atmosphere could not have formed without life Let’s take a look at current thinking Life can be classified according to energy sources and carbon usage:  Life can be classified according to energy sources and carbon usage Living organisms Energy source Sunlight Oxidation of inorganic (CO2,NO2,NH4+) Oxidation of organics Term Used Phototrophs Lithotrophs Heterotrophs Life can be classified according to energy sources and carbon usage:  Life can be classified according to energy sources and carbon usage Carbon Source Carbon Dioxide Organic material Term Used Autotroph heterotroph Examples:  Examples Photoautotroph Sun/CO2 Photoheterotrophs Sun/Carbon material Lithotrophic autotrophs Inorganic material Green plants,most algae, some bacteria Some algae, green bacteria, some cyanobacteria Hydrogen bacteria sulfur bacteria, nitrifying bacteria, iron bacteria Examples (more):  Examples (more) Lithotrophic heterotrophs Inorganic/Organic Conventional heterotrophs Organic/Organic Some colorless sulfur bacteria All animals, all fungi, all protozoa, most bacteria Back to the Biotic Atmosphere!!:  Back to the Biotic Atmosphere!! About 3.5 BYA What is BYA?? Billion Years Ago Amino acids first produced by abiotic processes Without them no life can form First life was extremely simple Prokaryotic Cells Simple strand of DNA No nucleus Conventional heterotrophs Examples of such life today are certain bacteria and blue green algae Back to the Biotic Atmosphere!!:  Back to the Biotic Atmosphere!! But Prokaryotic organisms still need a carbon source of some kind We have no known form of life that is not carbon based! The Biotic Atmosphere:  The Biotic Atmosphere Major energy process for Prokaryotes is fermentation C6 H12 O6  2C2H5OH + 2CO2 This reaction releases energy But life progressed! Life needed The Biotic Atmosphere:  The Biotic Atmosphere Methanogenesis Certain bacteria can use CO2 for a carbon source and molecular hydrogen for a energy source! Lithotrophic autotrophs 4H2 + CO2  CH4 + 2H2O This is an anaerobic reaction but more efficient in terms of energy production than fermentation An evolutionary advantage! Life needed The Biotic Atmosphere:  The Biotic Atmosphere Early molecular nitrogen Formed from NH3 NH3 + energy from sun  • • N • + 3H • • • N • + • • N •  N2 (need a catalyst) Once O2 levels began to build up (see below) this didn’t work Energy from sun needed was blocked out The Biotic Atmosphere:  The Biotic Atmosphere Denitrification developed An organic compound + NO3 •  CO2 + NO2 • Organic compound + • NO2  CO2 + N2 Needed life to do this Things continued… Denitrification is the source of most molecular nitrogen in atmosphere today The Biotic Atmosphere:  The Biotic Atmosphere Anoxygenic photosynthesis Most early organisms depended on organic/inorganic material Lived in water or underground At some point in distant mists of time Some bacteria developed ability to get energy directly from sunlight by a process called photosynthesis Early photosynthesis was a bit different then common brand we see today The Biotic Atmosphere:  The Biotic Atmosphere Anoxygenic photosynthesis CO2 + 2 H2S + sun energy  CH2O + H2O +2S CH2O is a simple form of a carbohydrate Major difference between this and regular photosynthesis? This reaction produced sulfur and not oxygen! There are still organisms like this around Blue green bacteria and yellow sulfur bacteria Life needed The Biotic Atmosphere:  The Biotic Atmosphere The oxygen age Obviously no oxygen or ozone until photosynthesis developed For a long time this was carried out by Cyanobacteria (about 1.9 billion years) Oxygen build up was very slow – only about 1% by concentration Land plants evolved from blue green algae about 400 million years ago Oxygen levels built up rapidly after that The Biotic Atmosphere:  The Biotic Atmosphere The big change was the development of chlorophyll Two types Chlorophyll a (favors red λ) Chlorophyll b (favors blue λ) Both absorb sunlight in the red (>0.6 μ ) and blue (< 0.5 μ) but not much in between Which of course is Green! The Biotic Atmosphere:  The Biotic Atmosphere The reaction is well known! 6CO2 + 6H2O + sunlight  C6H12O6 + 6O2 C6H12O6 is glucose The next big step!! Aerobic respiration! Green Plants The Biotic Atmosphere:  The Biotic Atmosphere With increased oxygen in the Earth’s atmosphere came a much more efficient energy producing system : Aerobic respiration The widespread development of aerobic respiration coincided with the rise of Eukaryotic organisms These organisms have DNA surrounded by nuclear membrane And can (and do ) form into complex multicellular organisms Such as the family mutt! The Biotic Atmosphere:  The Biotic Atmosphere The increase in oxygen also produced more ozone (O3) in the upper atmosphere and consequently less UV radiation Life could now safely emerge out on to the surface of the land The Biotic Atmosphere:  The Biotic Atmosphere Aerobic respiration C6H12O6 + 6O2  6CO2 + 6H2O The Oxygen Cycle:  The Oxygen Cycle Sources Photosynthesis by green plants Chemical production in the stratosphere and above Sinks Photolysis and kinetic reactions Aerobic respiration Dissolution into ocean waters Rusting Chemical reactions on soils surface Fuel combustion Geologic processes Oxygen in the atmosphere:  Oxygen in the atmosphere Oxygen concentration has varied over geologic time What is the current concentration of O2? This concentration changing will effect life and life forms. How? We all require O2 to extract energy from our food to produce the energy our bodies need. Oxygen in the atmosphere:  Oxygen in the atmosphere In periods of high oxygen concentration High biological innovation Huge insects Reptile flew Development of warm blooded mammal precursors Maganeura - prehistoric dragonfly:  Maganeura - prehistoric dragonfly Thrived 300 million years ago in high O2 concentrations Had a three foot wing span!! Oxygen in the atmosphere (con’t):  Oxygen in the atmosphere (con’t) In low oxygen concentration Biodiversity declines Mass extinctions Oxygen in the atmosphere (con’t):  Oxygen in the atmosphere (con’t) About 300 million years ago the atmospheric concentration of O2 was ~ 35% Really affected insects and arthropods dramatically – why? Higher O2 concentration would have increased O2 diffusion into these animals by 67% In that world millipedes were 3 ft long and dragonflies had wingspans of today’s hawks These assumptions are supported by controlled lab experiments today Oxygen in the atmosphere (con’t):  Oxygen in the atmosphere (con’t) About 250 million years ago there was a rapid depletion of O2 Went from ~30% to ~13% in ~10 million years What could have caused something like this? Earth previous had large carboniferous trees (turned into coal and oil) Went to small herbaceous plants i.e. ferns etc Knocked out 95% of species in oceans and 70% on land Oxygen in the atmosphere (con’t):  Oxygen in the atmosphere (con’t) As oxygen levels rebounded so also life responded For every atom of carbon sequestered in sediments an oxygen atom returns to the air ( made into coal/oil etc). As oxygen levels began to rebuild up to 16% agile reptiles developed (now in the Triassic) the dinosaurs, flying reptiles and the beginning mammals Higher O2 levels are good for mammals Need larger quantities of O2 for the warm body and developed brain ~ 1/3 of a mammal’s energy goes to supporting brain functions Oxygen in the atmosphere (con’t):  Oxygen in the atmosphere (con’t) ~ 50 million years ago the O2 levels began rising again Over the next 5 million years it rose to 21% Earth average temperature rose also ~ 7 degrees C Flora and fauna flourished ~ 25 million years O2 concentrations topped out at about 23% Many modern animals had developed by now Oxygen in the atmosphere (con’t):  Oxygen in the atmosphere (con’t) Some very large animals developed but died out Large animals don’t have as much capillaries per kg of muscle Can survive only in high oxygen world Smilodon californicus Sabre toothed tiger:  Smilodon californicus Sabre toothed tiger Woolly mammoths:  Woolly mammoths The Nitrogen Atmosphere:  The Nitrogen Atmosphere N2 in the atmosphere is primarily from denitrification N2 is removed from the air by nitrogen fixation Organic +NO3/NO2 to CO2+N2 The Nitrogen Atmosphere:  The Nitrogen Atmosphere N2 removed from air by Rhizobium Azotobacter Beijerinckia Convert N2 to NH4 Over all atmospheric concentration remarkably fixed:  Over all atmospheric concentration remarkably fixed Many constituents are constant Many are variable Particularly those essential for life Dynamic system:  Dynamic system Gases produced by biological activity, volcanoes, radioactive decay, anthropogenic activity Gases removed by: Chemical reactions Biological activity Physical processes Deposition Average gas residence time is from 4 hours to millions of years:  Average gas residence time is from 4 hours to millions of years Need to understand atmospheric constituents:  Need to understand atmospheric constituents Most “pollutants” in the atmosphere are naturally occurring Mt = Mg + Ms:  Mt = Mg + Ms Mt is total amount of gas exhaled from interior of Earth Mg is amount dissolved in oceans and air Ms is amount in sediments/soils If Mg is greater than Ms gas is accumulating Atmospheric gases:  Atmospheric gases Atmospheric gases con’t:  Atmospheric gases con’t Atmospheric gases con’t:  Atmospheric gases con’t CO2:  CO2 Strong seasonal changes Why?? Slide64:  The Hydrologic Cycle Water in the atmosphere:  Water in the atmosphere Water molecules constantly moving from gas solid vapor phases Energy required to liberate molecule of water from liquid to gas is called LATENT HEAT OF VAPORIZATION At surface of ice it is called LATENT HEAT OF SUBLIMATION The Reverse process is called condensation In this process energy is given to the receiving surface or when water condenses it releases energy! Latent heat of vaporization:  Latent heat of vaporization Very large Greater than almost all other common liquids Requires 580 calories per gram Makes water extremely efficient means of moving energy around the Earth Water molecules are strongly bipolar and this makes for strong molecular attraction Slide68:  The Hydrologic Cycle Water pressure:  Water pressure Water particles hitting surface provide pressure Partial pressure is pressure from one constituent i.e. water or O2 or CO2 etc Absolute humidity:  Absolute humidity Atmospheric concentration of water Saturated water pressure:  Saturated water pressure Water pressure at steady state Always molecules of water moving back and forth across a surface Estimates are that 2 to 3 kg of water per second move back and forth across m2 of open water If vapor pressure > saturation value water moves to surface (condensation) If vapor pressure < saturation value you have evaporation Saturation vapor pressure:  Saturation vapor pressure Increases with temperature Relative humidity:  Relative humidity The amount of water actually in the air divided by the amount of water the air could hold at saturation at that temperature

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