REGIONAL AND GLOBAL ATMOSPHERIC ASSESSMENT # 4

PART I.   CALCULATION OF PERSONAL PRODUCTION OF SULFUR DIOXIDE

     During the production of electricity by the the burning of coal, small amounts of sulfur in the coal also undergo the combustion reaction to make sulfur dioxide and ultimately sulfuric acid, which is the main component in acid rain.  In this exercise, you will calculate the amount of sulfur dioxide that may be produced to provide you with electricity.

QUES. 1:  In 1985, the total coal burned in the U.S. was 843 million tons, the population is 250 million, therefore each person is responsible for burning how many tons of coal?


QUES.  2:  How many pounds of coal are in the tons of coal consumed per capita per year calculated in Ques. 1 (1 ton = 2000 lbs)?



     Fossil fuels such as coal may contain compounds of sulfur which are converted into sulfur dioxide during the combustion reaction.  Coal from Southern Illinois may contain as much as 3 % sulfur by weight.  The ultimate question (answered in the next series of questions) is:  How much sulfur dioxide is produced by each person in the U.S.?

QUES. 3:  How many pounds of sulfur are in the  coal  calculated in Ques. 2?  Use the 3 % sulfur by weight for Illinois coal.


      The combustion reaction for sulfur in the coal is listed below.   Examine the equation to see whether further balancing the equations is needed.

A.     S    +         O2   ====>    SO2

QUES. 4.   Use eq. a);  How many moles of sulfur are used for the reaction?  Steps follow:
  
	a.  First find the atomic mass of sulfur from the periodic table for 1 mole of sulfur in pounds.  1 mole sulfur  =    ______lbs

     
	b.  Now find the  moles of sulfur in the pounds of sulfur from Ques. 3.

			ans. Ques. 3   x     1 mole S     =       _________ moles  S
						ans. a

QUES. 5:   Use eq. A:   If  ans. Ques. 4b _____ moles of sulfur are used, how many moles of sulfur dioxide are produced in this reaction?  Steps follow:
 
	a.  First what is the mole ratio?  ÒReadÓ the balance equation A above.
		1 mole S   =  ____ mole SO2  

	b.   ans. Ques. 4b    x      1 mole SO2        =   ___________ moles  SO2  
					ans. Ques. 5a



QUES. 6:  Use the answer to QUES. 5b - the moles of sulfur dioxide to calculate the pounds of sulfur dioxide produced by burning coal.
	a.  First find the atomic mass of sulfur dioxide from the periodic table for 1 mole of sulfur dioxide in pounds.  Add the atomic masses for 1 sulfur and 2 oxygen.

  	1 mole sulfur dioxide  =    ______lbs
     
	b.  Now find the  pounds of sulfur dioxide  in the moles of sulfur dioxide from Ques. 5b.
					ans. Ques. 5b   x     ans. 6a      =       _________ lbs SO2  
							      1 mole SO2  
  

QUES. 7:  The above calculation shows how many pounds of sulfur dioxide are produced by each citizen of the U.S. from the burning of  high sulfur coal with no pollution controls.  However, a modern coal fired plant is able to remove 70-95 % of the sulfur dioxide before it is emitted into the atmosphere.
	Use the ans. to Ques 6b and a figure of 30% sulfur dioxide actually emitted into the atmosphere to calculate how many pounds of sulfur dioxide enter the atmosphere for each citizen.






QUES. 8:   The sulfur dioxide in the atmosphere undergoes two more reactions to produce sulfuric acid which may become part of acid rain.  Balance equation B below. 

B.     SO2    +    O2    ====>    SO3
C.     SO3     +   H20   ====>    H2SO4
PART II.   PH OF RAIN AND OTHER NATURAL WATER SAMPLES

INTRODUCTION:

     Natural ÒcleanÓ water from melted snow or rain water has a normal pH of 5.6-5.2.  This natural ÒcleanÓ rain water may be found in only a few remote areas in the world.  You might expect that ÒcleanÓ  rain water would have a pH of 7.  The reason that it is not pH of 7, is that carbon dioxide from the air reacts with the water droplets to form carbonic acid.  Carbonic acid in rain water gives a pH of about 5.6.  Carbonic acid is normally found in many carbonated drinks.

     Acid snow or acid rain may contain additional acids in the form of sulfuric acid and nitric acid.  Sulfuric acid is formed by the reaction of sulfur trioxide with the water droplets.  Sulfur trioxide is formed from sulfur dioxide, which is formed when coal containing sulfur is burned at an electric power plant.

     Nitric oxide is formed during any combustion reaction at high temperatures such as during the burning of coal or in an automobile engine.  The nitric oxide reacts with oxygen to form nitrogen dioxide, which in turn reacts with water droplets to form nitric acid.

Procedure 1:  Collection of snow, rain or other natural waters
The goal will be to collect at least 8 different samples - several rain events and other natural water sources.
Snow or Rain Samples:
1.  In order to collect the snow or rain at the time of the event, you will need a clean glass or cup. Carefully clean the collection containers to be used.  If detergents are used, thoroughly rinse the container with lots of tap water.
2.  Choose a location that is away from trees and buildings.  Leave the collection container outside for the duration of the snow or rain event.
3.  If the snow is already on the ground, and is sufficiently deep and away from trees, scoop some snow into the container. Take the collection container inside, if snow is present,  let it melt. 
4.  Record significant information about the sample collection process:  date, time, snow or rain, duration of the event, details of the sample location area, and any other information that may be important.

Lake, River, or Pond Water:
1.  Follow #1 above for the collection container.  Being careful not to fall into the water, collect a grab sample from the appropriate body of water.
3.  Record significant information about the sample collection process:  date, time, snow or rain, duration of the event, details of the sample location area, and any other information that may be important.
4.  Be sure to wash your hands thoroughly after collecting a polluted water source.

Procedure 2.  PH MEASUREMENT OF WATER SAMPLES.
1.  As soon as possible after collecting the sample, use both the wide range and narrow range pH paper to measure the pH of the sample and record the results in table form.
2.  Discuss any significant findings or insights about the pH of various samples.
PART III.  ACID RAIN DISTRIBUTION IN THE UNITED STATES

     The National Atmospheric Deposition Program maintains a series of monitoring stations to measure acid rain and other associated ions.  
The www address is:  http://nadp.nrel.colostate.edu/NADP/

     A series of colored contour maps which give a visual picture of the distribution and concentration of various ions is available in the form of Isopleth Maps.

  	http://nadp.nrel.colostate.edu/NADP/isopleth_desc.html

Select 1995 maps  and then select the following ions for observation and analysis.

1.  1995 Field pH

QUES. 9:  Which areas of the country have the lowest pH values recorded?  What is the lowest pH and its location?

2.  1995 SO4-2 Concentrations (mg/L)

QUES. 10:  a.  Which areas of the country have the highest concentration of sulfate ion values recorded?  What is the highest sulfate ion concentration and its location?

b.  Which areas of the country have the highest carbon dioxide emissions which in turn correlate with the presence of mostly coal fired power plants? 
      see:  http://www.epa.gov/acidrain/scorcard/co295.gif
 
c.  What is the correlation between the deposition concentration and the emission of sulfur dioxide?
     see:  http://www.epa.gov/acidrain/scorcard/so295.gif  
     from http://www.epa.gov/acidrain/scorcard/es1995.html      Emission Scorecard 1995


3.  1995 NO3-1 Concentrations (mg/L)

QUES. 11:  a.  Which areas of the country have the highest concentration of nitrate ion values recorded?  What is the highest nitrate ion concentration and its location?

b.  What is the correlation between the deposition concentration and the emission of nitrogen oxides?
     see:  http://www.epa.gov/acidrain/scorcard/nox95.gif

QUES. 12:  a.  What is the correlation of pH,  sulfate ions, and nitrate ions in terms of location and high or low values?


b.  Why is the pH lowest for the northeast part of the country?


4.  1995 Ca+2 Concentrations (mg/L)

QUES. 13:  Which areas of the country have the highest concentration of Ca+2 ion values recorded?  What is the highest calcium ion concentration and its location?  Possible reason for high values?  (Hint:   Consider possible types of soil associated with wind carried dust which may derived from limestone, calcium carbonate.)


5.  1995 Cl-1 Concentrations (mg/L)

QUES. 14:  Which areas of the country have the highest concentration of chloride ion values recorded?  What is the highest chloride ion concentration and its location?  Possible reason for high values?  (Hint:   Consider that salt may enter the atmosphere from wind blown ocean spray)

Trends in acid rain pollutants:    The United States Geological Survey is responsible for monitoring the trends in acid rain and other ions as a result of the implementation of the Clean Air Act which calls for the reduction in sulfur dioxide emissions.  A detailed report and several graphics may be analyzed for information regarding the benefits of the first phase of sulfur dioxide emissions.  
     Color-scaled raster maps of the percent departures of 1995 annual hydrogen ion, sulfate, and nitrate concentrations from predictions of the 1983-1994 seasonalized trend models. The plus (+) signs indicate the location of NADP/NTN sites .  The models are based upon statistical methods to calculate a longer term trend for a ten year prior base period.  
     The main www site is:  http://h2o.usgs.gov/public/pubs/acidrain/
QUES.15:  a.  Analyze the three maps and draw conclusions about whether these results show less, more, or no change in percent concentrations from the predicted model behavior for i.e. are acid rain pollutants getting worse or better:
sulfur dioxide:  http://h2o.usgs.gov/public/pubs/acidrain/sulpct.gif
pH:  http://h2o.usgs.gov/public/pubs/acidrain/lphpct.gif
nitrogen oxides:  http://h2o.usgs.gov/public/pubs/acidrain/nitpct.gif

 b.  What has the general trend been in the sulfur dioxide emissions over the last 15 years?  http://www.epa.gov/acidrain/scorcard/so28095.gif 


PART III.  OZONE DEPLETION

     In 1987, an international agreement known as the Montreal Protocol on Substances that Deplete the Ozone Layer was signed by many nations.  The Protocol required the that CFC production would be reduced to one-half of the 1986 levels by 1998.  Based upon a growing understanding of the cause of the ozone hole and the potential for global ozone depletion, approximately 100 nations in 1990, agreed to a complete ban on the use of CFCs in 2000.  

Visualization of the Ozone Hole:

     Two sites are available to access contour color maps of the ozone concentrations in various locations in the world.  The longest archived series is from a satellite carrying TOMS - Total Ozone Mapping Spectrometer.  Another satellite provides daily maps called TOVS.

Note:  use the following www site to find answers to the questions that follow: 

QUES. 16:  First concentrate on the Antarctica, look at a series of images starting with January 1 and look at every other month for the whole year.  Which months show evidence of the Òozone holeÓ?  Try to refine the dates for the optimal duration of the ozone hole.  Try some dates that are about 15 days apart.  When does the ozone hole begin and end?

     TOMS:     http://jwocky.gsfc.nasa.gov/eptoms/ep.html
	EARTH PROBE TOMS HOME Page.  
a.  Click on Latest Polar Image or Latest Daily Image to get current real time data.  The color contour coding shows low ozone concentrations measured in Dobson units of gray, pink, violet colors.  Finding such colors is evidence of the ozone hole.  White or black colors mean that no data is available.

b.  Then use the right hand slide bar to go down about half way on the page, select Level 3 Daily Images for a world view and both polar views.  This will bring up a page containing 2 or more folder icons.  Choose either the current or past year such as y96.  Inside of this folder is an archive of images for the whole year.  The titles indicate dates such as: gf960725.gif (This means 96 = 1996, 07 = July, 25 = day).

c.  Use the back arrow key to go back to EARTH PROBE TOMS HOME Page.  About half way down under Other Neat Stuff, it is also possible to get a whole month of polar views by selecting Sept. Oct. or Nov.  
	

QUES. 17:  Give the approximate date and lowest concentration of ozone, in Dobson units, observed.


QUES. 18:  Is the distribution of ozone uniform over the surface of the globe during most times of the year such as during the summer months?  Comment on the ozone concentration levels near the equator, in the mid latitudes (North America/Europe) and polar regions.   Explain your observations. 

QUES. 19:   Is there any evidence of a similar ozone hole around the north polar region?  Look particularly at dates in Feb., Mar., and April. 
 
QUES. 20:  a.  Examine the ozone and reactive chlorine versus latitude graph below.  What is most striking about the relationships shown on the graph?  As the latitude increases (getting closer to the South Pole) the ozone concentration _________ while the chlorine concentration __________.

     The inactive forms of chlorine in hydrochloric acid and chlorine nitrate can react with ice crystals and nitric acid trihydrate crystals in very high cold clouds in the stratosphere over Antarctica.  This reaction on the surface produces diatomic chlorine molecule and nitric acid, which quickly dissociate into chlorine atoms in the sunlight of the Antarctic spring.  The reactive chlorine atoms start a cycle of destruction of ozone.  Chlorine atoms react with ozone to make chlorine monoxide molecules and oxygen molecules.  Chlorine monoxide reacts with atomic oxygen to make diatomic oxygen and reactive chlorine atoms to cycle over again.  Since there are few gaseous water molecules and virtually no nitrogen dioxide molecules to react with and inactivate the chlorine, the reactive chlorine builds up as chlorine monoxide.

b.  What is the series of chemical reactions which would explain the graph data?