I. Carbon Cycle

This Carbon Cycle model is from the Okanagan University College in British Columbia, Canada

•     What's the difference between the source of carbon and a carbon sink?

•     FALSE : Even though Earth's atmosphere contains only .03% CO₂  this gas DOES significantly contribute to   heat trapped in Earth's lower atmosphere.

•     What's the conclusion about CO₂  shown in the research data graph (in the pdf file)?

•     What are the 2 main human activities which release carbon into the air that have increased significantly in the last 150 years?

•     Based on this research and any other articles that you have read, do you think that humans are contributing significantly to global warming (if this is indeed occuring at all)? [*N.B. You can choose either Yes or No, but please be ready to JUSTIFY (support with evidence) YOUR ANSWER.]

•     On p.13 of the article above, what did the USA and other countries agree to in the Kyoto Protocol (on Nov.,"98)? Do you think that this is cutting back enough? Explain.

II.Nitrogen Cycle

This Nitrogen Cycle model is also from the Okanagan University College in British Columbia, Canada

** Go to the Article on "Nutrient Overload:Unbalancing the Global Nitrogen Cycle" from the  World Resources Institute, and answer these questions below (in your copybook):

1) According to the World Resources Institute, what are the 2  negative effects of excess Nitrogen in water and on land?
      Excess nitrogen from human activities (such as agriculture, energy production, and transport) has begun to overwhelm the natural nitrogen cycle with a range of ill effects from  #1. diminished soil fertility  to  #2 toxic algal blooms. (p.1 of 5)

2) Why are Nitrogen-fixing bacteria important to plants?
    Although N2 is the most abundant element in the atmosphere, Nitrogen from the air must be chemically transformed (or fixed) into ammonium or nitrate compouns that plants can metabolize.

3) Since the 1940's what 3 human activities have caused Nitrogen uptake to double?
    Driven by a massive increase in the use of fertilizer, the burning of fossil fuels, and an upsurge in land clearning and deforestation, the amount of nitrogen available for uptake at any given time has more than doubled since the 1940's.

4) Because of excessive Nitrogen deposits in the Netherlands, changes have occured. Which plants are dominant, and how are the ecosystems changing?
     In the Netherlands, where nitrogen deposition rates are among the highest in the world, whole ecosystems have been altered because of this shift in dominant plants, with species-rich heathlands being converted to species-poor forests and grasslands that better accommodate the nitrogen load.

5) According to this article, how does excess Nitrogen in runoff affect water ecosystems?
    (Sewage is very high in nitrogen from protein int he human diet.) In these aquatic systems, excess nitrogen often greatly stimulates the growth of algae and other aquatic plants. When this extra plant matter dies and decays, it can rob the water of its dissolved oxygen, suffocating many aquatic organisms.
6) Where are the water environments most vulnerable to eutrophication?
    The areas most threatened are coastal estuaries  and inshore waters where most commercial fish and shellfish species breed. [Partially encolsed seas such as the Baltic Sea, the Black Sea, and even the Mediterranean have also been hard hit by nitrogen-caused eutrophication, and an extensive "dead zone" of diminished productivity has developed at the mouth of the Mississippi River in the Gulf of Mexico because of the large influx of nitrogen from agricultural runoff.
    [ This overfertilization process, called eutrophication, is one of the most serious threats to aquatic environments today, particularly in coastal estuaries and inshore waters where most commercial fish and shellfish species breed.]
7) What 3 strategies do the authors recommend to cut down on the detrimental effects of excess Nitrogen in land and water?
    Many of the same strategies used to reduce carbon dioxide emissions benefit cutting airborne nitrogen emissions from fossil fuels... These include: (1) a greater emphasis on energy efficiency, (2) a gradual shift toward alternative energy sources, and the (3) use of low-nitrogen technology in power plants and cars. Other strategies make sense as well, such as restoration of wetlands, which are natural nutrient traps that sponge up excess nitrogen before it can damage aquatic systems.

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III. Water Cycle

This Water Cycle model is from the Water Environment Association of Texas & EPA

    1) What

I.Carbon Cycle
  1. The

(Source: Arms, Karen, Ph.D., Environmental Science,Holt Rinehard Winston, 2004)
 

II.Nitrogen Cycle

III.Water Cycle
  1. The answer