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Topic 4: Ecology (4.3 Carbon Cycling (Release of Carbon Dioxide from Cell…
Topic 4: Ecology
4.3 Carbon Cycling
Carbon Fixation
autotrophs absorb carbon dioxide from the atmosphere and convert it to carbohydrates, lipids, and other carbon compounds
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Oxidation of Methane
those that diffused out will only stay there by 12 years because they are naturally oxidized by the atmosphere
Peat Formation
when soil gets waterlogged, there will not be enough oxygen for saprotrophs
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saprotrophs cannot survive, dead organic matter is not fully decomposed
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Limestones
animals such as reef-building corals and molluscs have hard parts that are composed of calcium carbonate and can become fossilized in limestone
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4.4 Climate Change
Greenhouse Effect
Cause:
-Light from the Sun has short wavelengths and can mostly pass through the atmosphere.
-Sunlight warms up the surface of the Earth which emits long-wave radiation.
-Long-wave radiation absorbed by the gases in the atmosphere.
-The gases re-emit the radiation and some of it passes back to the surface of the Earth, causing warming.
Greenhouse gases:
Carbon dioxide and water vapour are the most significant greenhouse gases.
Methane and nitrogen oxides also have an effect, but it is smaller.
Global Warming:
What is strongly disputed by some people is whether global warming and other climate changes are due to greenhouse gas emissions from human activity. This claim has been evaluated by many climate change scientists, who have almost all
concluded that human activity is indeed influencing the global temperatures and climate patterns.
Carbon Emission:
Carbon dioxide concentrations and global temperature are correlated but are not directly proportional as there are other variable factors that affect temperatures. As a result global warming is much more uneven year on year than rises in C02. There may be periods of slower temperature rise despite C02 increases but also periods of particularly rapid temperature increase.
In addition to its contribution to global warming, emissions of carbon dioxide are having effects on the oceans.
Marine animals such as reef-building corals that deposit calcium carbonate in their skeletons (above) need to absorb carbonate ions from seawater. The concentration of carbonate ions in seawater is low, because they are not very soluble. Dissolved carbon dioxide makes the concentration even lower as a result of some interrelated chemical reactions. Carbon dioxide reacts with water to form carbonic acid, which dissociates into hydrogen ions and hydrogen carbonate ions. Hydrogen ions convert carbonate into hydrogen carbonate. With reduced carbonate concentrations in seawater not only can new calcium carbonate not be made, but it dissolves in existing corals, threatening the existence of all reef ecosystems.
