Topic 4: Ecology
4.3 Carbon Cycling
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.
Carbon Fixation
Carbon Dioxide in Solution
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.
autotrophs absorb carbon dioxide from the atmosphere and convert it to carbohydrates, lipids, and other carbon compounds
reduce carbon dioxide from the atmosphere
Carbon dioxide is soluble in water
Form carbonic acid
Remain as dissolved gas
reduce pH of the water
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absorbed by aquatic plants to make carbon compounds
Release of Carbon Dioxide from Cell Respiration
animal cells
saprotrophs
non-photosynthetic parts of producers
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.
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Create Carbon dioxide
Carbon dioxide diffuse out of cells in to atmospheres and water
Methanogenesis
produced by organic matters in anaerobic environment
archeans
some of the methane diffuse out into the atmosphere
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
saprotrophs use oxygen in the soil during respiration
anaerobic environment
saprotrophs cannot survive, dead organic matter is not fully decomposed
Carbon Emission:
acidic environment
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.
Fossilized Organic Matter
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.
Oil and Natural Gas
Coal
peat is heated and compressed
formed when deposits of peat are buried under other sediments
formed in the mud at the bottom of sea and lakes
Most of the natural gas is methane
Absorption of Carbon Dioxide
carbon dioxide is used by autotrophs
carbon dioxide concentration is high in the atmosphere and water around them
concentration gradient
diffusion of carbon dioxide into autotrophs
Combustion
carbon dioxide is created by the combustion of fossilized organic matter
Limestones
animals such as reef-building corals and molluscs have hard parts that are composed of calcium carbonate and can become fossilized in limestone
Carbon cycle diagrams
