Anthropogenic Sulfur Dioxide 
    in the Troposphere
     
    TABLE OF CONTENTS
      1. The Authors
      2. Introduction
      3. National Standards
      4. Hypothesis
      5. STELLA Model
      6. STELLA Formulae
      7. Resources
       
    Introduction
     
      Sulfur dioxide (SO2) and  nitrous oxide emisions released into the atmosphere are the leading causes of acid rain. Emisions of SO2 occur naturally through plant decomposition and volcanic erruptions.  However, since the industrial revolution, humans have contributed greatly to an increase in the rate of these emissions.  Emissions from powerplants which burn coal to produce electricity, along with oil refining processes and ships which burn bunker fuel are the main sources of SO2 emissions produced by man. These emissions, referred to as anthrophogenic , are regulated through the Clean Air Act Amendment of 1990 (CAAA) by the Enviromental Protection Agency.
            Acid rain has resulted in increased acidity of lakes and streams, a decrease in fish population diversity and health, increased soil degradation and forest stress, a reduction in visibility (SMOG), an increase in human health problems, and an increase in damage to materials and cultural resources.  (Acid Deposition Standard Feasibility Study Executive Summary...Acid Rain Program http://www.epa.gov/acidrain/effects/execsum.html).  The United States is very concerned about these problems and have enforced regulations for SO2 emissions. It is expected that these regulations will result in well over a 50% reduction in average annual SO2 deposition by the year 2010. (http://www.epa.gov/acidrain.effects/tbl6.html)  These reductions by Canada and the United States does not mean that the problem of SO2 pollution is solved.  It is expected that with the industralization of Third World Countries,  SO2 production will be increasing at a rapid rate.  Therefore, world wide monitoring of these emissions is becoming more important.
            This project is a Stella Model based on the work of Madalinski, Nichols and Martens (Global Effect of Natural and Anthrophogenic Sulfur Dioxide Emissions at http://www.civil.mtu.edu/~ajdil/classes/ce459/projects/RO8/intro.htm
    They list six sources (or reservoirs) of sulfur dioxide in the natural sulfur cycle.  These are the lithosphere, oceans, freshwater, terrestial biota, ocean atmosphere and the continental atmosphere. The sulfur fluxes in this cycle are from the works of Butcher et al. as reported by Madalinski et al. and by Samuel S. Butcher, editor Global Biogeochemical Cycles (1992).  Future work will be to identify possible biological remediation strategies. Plans are to involve students worldwide in data collection and problem solving techniques.
     
    National Standards

         You may view the National Science Education Standards  for grades 9-12  addressed by the activity by selecting any of the curriculum areas below.
     
                    Physical Science 
                    Life Science
                    Earth Science
                    Inquiry 
                    Science and Technology
                    History and Nature of Science
                    Science in Personal and Social Perspectives

     

     Hypothesis

        We contend that modeling will predict areas of sulfur dioxide concentrations on the earth.   As the project continues, we expect to find organisms which will produce benign substances from derivatives of sulfur dioxide emissions.
     

    Procedure
     

          We have found a research model which used the STELLA model, this paper gives data on natural and anthropogenic SO2 levels.  The next step of this project is to use the model with our high school classes to begin collection of data based on the precitions of the model.  We wil be using the LaMotte test kit for SO2.
     

    The STELLA Model of the Sulfur Cycle

        Our model of the sulphur cycle is based on the work of Madalinski, Nichols and Martens, Global Effect of Natural and Anthropogenic Sulfur Dioxide Emissions.
    We copied their model into the STELLA program but were unable to achieve a steady state as presented in their paper.  Based on the data of  Charlson, Anderson and McDuff in Global Biogeochemical Cycles  (1992) modifications were made to the model and the underlying formulae in order to achieve a balanced system.
        After equilibrium among the reservoirs was established in a system without human influence,  a "flow" was added which allowed the introduction of anthropogenic sufur dioxide (SO2) into the cycle.  Additionally, the model includes controls which allow one to vary the levels SO2 from volcanic eruption and from human activity.
     
     

    Units in stocks are Tg = 10^12 g sulphur

    Sulfur fluxes are in Tg/year
     


    Figure A

        Rectangles in the model (Figure A) represent reservoirs of sulfur in the system.  The arrows indicate the direction of sulphur flow.  Flow rate of the sulfur is controlled by constants or formulae associated with each circle.  Those circles with symbols indicate the variables which may be adjusted.  The controls labeled "Del . . ." calculate the difference between the initial value and ending value of stocks with a value so large that small changes would go unnoticed.  The cloud shapes represent the boundaries of the system.

     

    Figure B

    The top six boxes figure B are examples of monitors which show changes in sulfur volumes of the reservoirs.  The bottom four figures are the control devices which allow changes to be made in flow rates.

    Figure C
     

    Figure D
     

        Figures C and D show the model running in a steady state.  The variation from horizontal in Figure C are due to possible errors in data or to the use of constants within the formulae used to calculate flow rates.  However, when one considers the magnitude of the change over an extended period of time, one can reasonably assume that a steady state has been achieved.

    Figure E
     

    Figure F

        Figures E and F represent the introduction of sulfur via anthropogenic sources.  The levels of  introduced sulfur were manipulated by using the "Sulfur Use Graph" and the "Sulfur Use" switch (Figure B).  Sulfur compounds introduced into the continental atmosphere by fossil fuel burning, remain in the atmosphere for a very brief period of time.   Sulfur levels in the Continental Atmosphere, Ocean and Freshwater reservoirs rise at a rate corresponding to that established in the Sulfur Use Graph (Figure B).  Therefore, sites for collection of air samples may be predicted with this model by monitoring the appropriate STELLA reservoirs and flow rates.

    STELLA FORMULAE

    Below are the formulae used in the STELLA model described above.

    Continental_Atm(t) = Continental_Atm(t - dt) + (To_Cont_Atm + Net_Transport + Anthro_emissions_1 - Dep_from_Cont_Atm) * dt

    INIT Continental_Atm = 1.6

    INFLOWS:
    To_Cont_Atm = Aeolian_Emissions+Terr_BiogenicGases+Volcanic_to_Cont_Atm
    Net_Transport = 11*(Ocean_Atm-Continental_Atm)/(INIT(Ocean_Atm)-INIT(Continental_Atm))
    Anthro_emissions_1 = 0.75*Sulfur_Use*sulfur_use_on\off
    OUTFLOWS:
    Dep_from_Cont_Atm = 58*Continental_Atm/INIT(Continental_Atm)
    Fresh_water(t) = Fresh_water(t - dt) + (seepage + Dep_from_Cont_Atm + Weathering_to_freshwater - River_runoff - from_freshwater_to_lithosphre) * dt

    INIT Fresh_water = 250

    INFLOWS:
    seepage = 8*INIT(Terrestrial_Biota)/Terrestrial_Biota
    Dep_from_Cont_Atm = 58*Continental_Atm/INIT(Continental_Atm)
    Weathering_to_freshwater = 93*Lithosphere/INIT(Lithosphere)
    OUTFLOWS:
    River_runoff = 104*Fresh_water/INIT(Fresh_water)
    from_freshwater_to_lithosphre = Burial_from_Freshwater
    Lithosphere(t) = Lithosphere(t - dt) + (flow_into_lithosphere - flow_out_from_lithosphere - Weathering_to_freshwater) * dt

    INIT Lithosphere = 2e10

    INFLOWS:
    flow_into_lithosphere = Burial_from_Freshwater+burial_from_ocean
    OUTFLOWS:
    flow_out_from_lithosphere = Aeolian_Emissions+Nutients_to_biota+Volcanic_to_Ocean_Atm+Volcanic_to_Cont_Atm
    Weathering_to_freshwater = 93*Lithosphere/INIT(Lithosphere)
    Ocean(t) = Ocean(t - dt) + (River_runoff + Dep_from_Ocean_Atm - flux_from_ocean) * dt

    INIT Ocean = 1.3e9

    INFLOWS:
    River_runoff = 104*Fresh_water/INIT(Fresh_water)
    Dep_from_Ocean_Atm = 187*Ocean_Atm/INIT(Ocean_Atm)
    OUTFLOWS:
    flux_from_ocean = burial_from_ocean+Oceanic_Biogenic_Gases+Sea_Spray
    Ocean_Atm(t) = Ocean_Atm(t - dt) + (To_Ocean_Atm + Anthro_emissions_2 - Net_Transport - Dep_from_Ocean_Atm) * dt

    INIT Ocean_Atm = 3.2

    INFLOWS:
    To_Ocean_Atm = Oceanic_Biogenic_Gases+Sea_Spray+Volcanic_to_Ocean_Atm
    Anthro_emissions_2 = .2*Sulfur_Use*sulfur_use_on\off
    OUTFLOWS:
    Net_Transport = 11*(Ocean_Atm-Continental_Atm)/(INIT(Ocean_Atm)-INIT(Continental_Atm))
    Dep_from_Ocean_Atm = 187*Ocean_Atm/INIT(Ocean_Atm)
    Terrestrial_Biota(t) = Terrestrial_Biota(t - dt) + (Flux_to_Terr_Biota - seepage - Terr_biota_to_atm) * dt

    INIT Terrestrial_Biota = 3e5

    INFLOWS:
    Flux_to_Terr_Biota = Nutients_to_biota+0.05*Sulfur_Use*sulfur_use_on\off
    OUTFLOWS:
    seepage = 8*INIT(Terrestrial_Biota)/Terrestrial_Biota
    Terr_biota_to_atm = Terr_BiogenicGases
    Aeolian_Emissions = 20*Lithosphere/INIT(Lithosphere)
    Burial_from_Freshwater = 35*Fresh_water/INIT(Fresh_water)
    burial_from_ocean = 125.9*Ocean/INIT(Ocean)
    Del_litho = Lithosphere-INIT(Lithosphere)
    Del_ocean = Ocean-INIT(Ocean)
    Nutients_to_biota = 26*Lithosphere/INIT(Lithosphere)
    Oceanic_Biogenic_Gases = 39*Ocean/INIT(Ocean)
    Sea_Spray = 140*Ocean/INIT(Ocean)
    sulfur_use_on\off = 1.0
    Terr_BiogenicGases = 18*Terrestrial_Biota/INIT(Terrestrial_Biota)
    Volcanic_to_Cont_Atm = Volcano_m*Lithosphere/INIT(Lithosphere)
    Volcanic_to_Ocean_Atm = Volcano_k*Lithosphere/INIT(Lithosphere)
    Volcano_k = 19
    Volcano_m = 9
    Sulfur_Use = GRAPH(TIME)
    (0.00, 69.8), (15.0, 69.8), (30.0, 70.5), (45.0, 69.8), (60.0, 70.5), (75.0, 70.5), (90.0, 69.8), (105, 70.5), (120, 70.5), (135, 71.3), (150, 70.5)

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    Physical Science   
        1.  STRUCTURE OF MATTER   
            1.1   Matter is made of atoms, atoms are composed of even smaller components   
        2. STRUCTURE AND PROPERTIES OF MATTER   
            2.1   Atoms interact with one another   
            2.2   An element is composed of a single type of atom   
            2.3   Bonds between atoms are created when electrons are transferred or shared   
            2.4   The physical properties of compounds reflect the nature of the molecular   
                    interactions   
        3.  CHEMICAL REACTIONS   
            3.1   Chemical reactions occur all around us   
            3.2   Chemical reactions may release or consume energy   
            3.3   A large number of important reactions involve the transfer of electrons or  
                    hydrogen ions   
            3.4   Chemical reactions can take place in time periods ranging from a few   
                    femtoseconds   
                    to billions of years   
            3.5   Catalysts accelerate chemical reactions   
        4. MOTIONS AND FORCES   
            4.3   The electric force is a universal force that exists between any two charged  
                    objects   
        5.  CONSERVATION OF ENERGY AND THE INCREASE IN DISORDER   
            5.3   Heat consists of random motion and vibrations of atoms, molecules and ions   
        6.  INTERACTIONS OF ENERGY AND MATER   
            6.3   Each kind of atom or molecule can gain or lose energy  in particular discrete   
                    amounts and thus can absorb and emit light only at wavelengths corresponding  
                    to these amounts.  

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    Life Science 
        4.  THE INTERDEPENDENCE OF ORGANISMS 
            4.1  The atoms and molecule on the earth cycle among the living and nonmoving 
                    components of the biosphere 
            4.5  Human beings live within the world's ecosystems 
        5.  MATTER, ENERGY, AND ORGANIZATION IN LIVING SYSTEMS 
            5.2  There energy for life primarily derives from the sun 
        6. THE BEHAVIOR OF ORGANISMS 
            6.4  Behavioral biology has implications for humans, as it provide links to 
                   psychology, sociology and anthropology. 
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    Earth Science 
        1. ENERGY IN THE EARTH'S SYSTEM 
            1.1  Earth systems have internal and external sources of energy, both of which 
                   create heat 
            1.3  Heating of earth's surface and atmosphere by the sun drives convection within 
                   the atmosphere and oceans, producing winds and currents 
            1.4  Global climate is determined by energy transfer from the sun at and near the 
                   earth's surface. 
        2. GEOCHEMICAL CYCLES 
            2.2  Movement of matter between reservoirs is driven by the earth's internal and 
                    external sources of energy 
     
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    Inquiry  
        1.  Identify questions and concepts that guide scientific investigation 
        2.  Design and conduct scientific investigation 
        3.  Use technology and mathematics to improve investigations and communications 
        4.  Formulate and revise scientific explanations and models using logic and evidence 
        5.  Recognize and analyze alternative explanations and models 
        6.  Communicate and defend a scientific argument. 
        7.  Understandings about scientific inquiry. 
            7.1   Scientists usually inquire about how systems function 
            7.2   Scientists conduct investigations for a wide variety of reasons. 
            7.3   Scientists rely on technology to enhance the gathering and manipulation of 
                    data 
            7.4   Mathematics is essential in scientific inquiry. 
            7.5   Scientific explanations must adhere to criteria 
            7.6   Results of scientific inquiry--new knowledge and methods--energy from 
                   different types of investigation and public communication among scientists 
     
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    Science and Technology   
        1. IDENTIFY APPROPRIATE PROBLEMS FOR TECHNOLOGICAL  
            DESIGN   
        2. DESIGN A SOLUTION OR PRODUCT   
        3. IMPLEMENT A PROPOSED SOLUTION   
        4. EVALUATE COMPLETED TECHNOLOGICAL DESIGNS OR  
            PRODUCTS   
        5. COMMUNICATE THE PROCESS OF TECHNOLOGICAL DESIGN   
        6. UNDERSTANDINGS ABOUT SCIENCE AND TECHNOLOGY   
            6.2   Science often advances with the introduction of new technologies   
            6.3   Creativity, imagination, and a good knowledge base are all required in the  
                    work of science and engineering.   
            6.4   Science and technology are pursued for different purposes  
     
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    History and Nature of Science 
        1. SCIENCE AS A HUMAN BEHAVIOR 
            1.1  Individuals and teams have contributed and will continue to contribute to the 
                   scientific enterprise 
            1.2  Scientists have ethical traditions 
            1.3  Scientists are influenced by societal, cultural, and personal beliefs and ways of 
                   viewing the world. 
        2. NATURE OF SCIENTIFIC KNOWLEDGE 
            2.1   Science distinguishes itself from other ways of knowing and from other bodies 
                    of knowledge through the use of empirical standards, logical arguments, and 
                    skepticism, as scientists strive for the best possible explanations about the 
                    natural world. 
            2.2   Scientific explanations must meet certain criteria. 
            2.3   Because all scientific ideas depend on experimental and observational 
                    confirmation, all scientific knowledge is, in principle, subject to change as new 
                    evidence becomes available. 
        3. HISTORICAL PERSPECTIVES 
            3.2   In history, diverse cultures have contributed scientific knowledge and 
                    technologic inventions. 
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    Science in Personal and Social Perspectives   
        1. PERSONAL AND COMMUNITY HEALTH   
            1.1 Hazards and potential for accidents exist   
        2. POPULATION GROWTH   
            2.1  Populations grow or decline through the combined effects of births and deaths,   
                  and through emigration and immigration.  Populations can increase. . .with  
                  effects on resource use and environmental pollution.   
        3. NATURAL RESOURCES   
            3.1  Human populations use resources in the environment in order to maintain and  
                   improve their existence.   
            3.2  The earth does not have infinite resources   
            3.3  Humans use many natural systems as resources.   
        4. ENVIRONMENTAL QUALITY   
            4.1  Natural ecosystems provide an array of basic processes that affect humans   
            4.2  Materials from human societies affect both physical and chemical cycles of the   
                   earth.   
            4.3  Many factors influence environmental quality.   
        5.  NATURAL AND HUMAN-INDUCED HAZARDS   
            5.2   Human activities can enhance potential for hazards   
            5.4   Natural and human-induced hazards present the need for humans to assess   
                    potential danger and risk.   
        6.  SCIENCE AND TECHNOLOGY IN LOCAL, NATIONAL, AND GLOBAL  
            CHALLENGES   
            6.1   Science and technology are essential social enterprises , but alone they can  
                    only indicate what can happen, now what should happen.   
            6.2   Understanding basic concepts and principles of science and technology should  
                    precede active debate about the economics, policies, politics and ethics of   
                    various science- and technology-related challenges.   
            6.3   Progress in science and technology can be affected by social issues and  
                    challenges   
            6.4   Individual and Society must decide on proposals involving new research and 
                    the introduction of new technologies into society.   
            6.5   Humans have a major effect on other species.   
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     Other Resources
     
    Charleson, R.J., Anderson, T.L., McDuff, R.E. (1992)  The Sulfur Cycle. in Butcher, Samuel S. (ed). Global Biogeochemical Cycles.   Academic Press Limited

    Charlson, R.J., Orains, G.H., Wolfe, G.V. and Butcher, S.S. (1992), Human Modification of Global Biogeochemical Cycles in Butcher, Samuel S. (ed). Global Biogeochemical Cycles.   Academic Press Limited

        Activities and experiments in Environmental Chemistry can be found through the Woodrow Wilson Nation Fellowship Foundation web page.

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    Sharon Kirby (l), Bart James (c), and Tamsey Ellis (r)--Team 17

    Tamsey Ellis                            Bart James                                        Sharon Kirby
    Maryvale High School             Trevor G. Browne H.S.                     Marietta High School
    3415 N. 59th Avenue              7402 W. Catalina Dr.                        121 Winn St.
    Phoenix, AZ   85033               Phoenix, AZ   85033                         Marietta, GA  30064
    twellis@aol.com                      b..james@qm.phxhs.k12.az.us           skirby@aol.com
     

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