The Greenhouse Effect: By Amanda Scott

. The Greenhouse Effect: By Amanda Scott The Greenhouse Effect:

Amanda Scott

Nitrous Oxide Emission through Plants

Due to anthropogenic activity, the concentration of Nitrous Oxide (N2O) in the
atmosphere is increasing. This can cause an enhanced "greenhouse" effect and
can eventually lead to higher UV-B intensity on earth. N2O emission is usually
said to be caused by diffusion up through the sail {soil?] profile. N2O may,
also, come from plants growing in soils with high N2O concentration. A
hypothesis was given: "We postulate that significant amounts of N2O may be
released from upland agricultural soils via plant respiration." Testing N2O
emissions from barley and canola plants under a controlled environment set up
an experiment. The shoots from these plants were placed in chamber and the N2O
concentration was measured in accordance with time. Chambers were closed for 6
hours and 5-mL samples of air were removed at every hour. In Treatment 1 where
soil was watered to field capacity, N2O concentrations remained at ambient
levels. In Treatment 2, soil was saturated just before it was tested. There
were slightly higher concentrations. In Treatment 3, water was added to the
soil column containing N2O. In the chamber N2O concentrations increased
steadily. Around the soil the N2O increased sharply and then declined. In
Treatment, 4 the concentration of N2O was function of volume of solution of
N2O that was applied. The observation: "Plants did not generate N2O directly,
but merely conveyed N2O produced in the soil." The experiment suggests that
N2O released from plant tissues may be a common phenomenon. The rate will
depend largely on the concentration of N2O in the soil solution.

The Pros and Cons of Carbon Dioxide Dumping

To avoid the release of carbon dioxide (CO2) into the atmosphere, methods of
capture and disposal are being investigated. Critics' question the safety,
cost, and need for a solution. They seem to say that companies should be
focusing on the reduction of the use of fossil fuels. Ocean disposal and
storage is more disputed that storing it underground. This is because of
potential impacts on marine organisms due to pH change in the ocean. It is
expensive to remove CO2 chemically from power plants waste. Other CO2 recovery
processes have been considered. They include cryogenic fractionation, membrane
separation, and adsorption using molecular sieves. These, however, are more
expensive and less energy efficient. Therefore, power companies dislike the
idea of CO2 disposal techniques. But before companies could even embark in
large-scale disposal, liability questions would have to be answered. Direct
ocean dumping presents safer alternatives, but only to humans. Yet it takes
1000 years too long to even out quick increases of CO2 in air. It faces other
hurdles, like the Ocean Duping Act passed in 1972. Many scientists are still
skeptical about the solutions to remove CO2 from the atmosphere.

REFERENCES

Chang, C., H. H. Janzen, C.M. Cho, and E.M. Nakonechny, 998, Nitrous oxide emissions through plants: Soil Science Society of AmericaJournal, v 62, p 35-39.

Harnish, C., 1998, The Pros and Cons of Carbon Dioxide Dumping: Environmental Science and Technology, v 32, p 20A-25A.

Schimel, David S., 1998, The Carbon Equation: Nature, v 393, p 208-209.

LINKS TO OTHER SITES

DiagramA simple diagram of the greenhouse effect with an explanation.

Climate Change[BAD LINK]Goes into detail about the enhanced greenhouse effect and provides many other links.

EPA's Global Warming PageThe United States Environmental Protection Agency's web page. It provides information and resources on what is known, potential impacts, and what can be done.

Summary

The greenhouse effect is a phenomenon caused by carbon dioxide and water vapor in the atmosphere. These gases keep the Earth warm by trapping heat that radiates from the earth's surface. Without this effect, the earth would be a frozen wasteland. In other words, we need this phenomenon in order to survive. In today's world, everyone has probably heard of the greenhouse effect. There is much concern as to how high the Earth's temperatures are reaching. This, scientists believe, is due to excess greenhouse gases (methane, chlorofluorocarbons, nitrous oxide, but mainly carbon dioxide) in the Earth's atmosphere. Human activity is the main cause. Factories are putting out so much carbon dioxide that world leader hold meeting to discuss what can be done. They brain solve trying to figure out possible solutions to the excess carbon dioxide. Some ideas so far are burying the carbon dioxide underground, placing it in oil wells to help pump out oil, and even thoughts about axing the factories who pump out billions of pounds of carbon dioxide everyday. Many scientists are debating these solutions because they are unsure of the safety. Not only are scientists concerned about human emissions of greenhouse gases, but they are also looking into other sources. Recently an experiment was done to test the emissions of nitrous oxide from plants. They found that the plant gives off this gas after having taken it in through the soil. As you can see, there is much concern over the greenhouse effect in the world today. These concerns are about the contributions that the greenhouse effect makes to global warming.

[The results shown below did not work out very well, you have to use the "table" functions of HTML to obtain the proper alignment. I will try to post a "table" version at the end of the week - S.K.]

This is a chart of steps in the greenhouse effect ----------------------------------------------------------------------------- --------------------------------------------------- Step 1 Step 2 Step 3 Results Energy from the sun The atmosphere isn't The atmosphere is The more carbon dioxide Is absorbed by the transparent to infrared heated and the heat the warmer the atmos- Earth's surface as rays because carbon radiates back to the phere. The less carbon Invisible infrared rays. Dioxide and water Earth's surface. Dioxide, the cooler the Molecules strongly atmosphere. Absorb the rays in- Stead of allowing Them to escape. ----------------------------------------------------------------------------- --------------------------------------------------- The reference I suggest the most is one of the web pages that I have already provided. It is provided again below. EPA's Global Warming Web Site

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