BACC 106 Carbon cycle 2012.ppt

1、The Carbon cycle,Carbon is the: fourth most common element on earth basis of all life, continually cycled, and globally conserved.,The Carbon cycle,Carbon is stored on our planet in the following major pools: as organic molecules in living and dead organisms found in the biosphere; as the gas carbon

2、 dioxide in the atmosphere; as organic matter in soils; in the lithosphere as fossil fuels and sedimentary rock deposits such as limestone, dolomite and chalk; in the oceans as dissolved atmospheric carbon dioxide and as calcium carbonate shells in marine organisms.,The Carbon cycle,Carbon is exchan

3、ged between pools by: photosynthesis and respiration between the land and the atmosphere, and diffusion between the ocean and the atmosphere.,The Carbon cycle,Photosynthesis Energy (sunlight) + Water (H2O) + Carbon dioxide (CO2) Carbohydrates + Oxygen (O2) Respiration Glucose (C6H12O6)+ Oxygen (O2)

4、Carbon dioxide (CO2)+ water (H20)+ Energy Decomposition - breakdown of matter by bacteria and fungi,The Carbon cycle,/Features/Carbon Cycle/carbon _cycle2.php,The Carbon ,Water can dissolve limestone and wash it into the ocean, where it can precipitate and form sedimen

5、t on the sea floor. Some of these sediments are moved underneath the continents by plate tectonics. The intense heat and pressure deep below the Earths surface melts the limestone which reacts with other minerals and releases carbon dioxide. Carbon dioxide is then re-emitted into the atmosphere thro

6、ugh volcanic eruptions./Features/CarbonCycle/carbon_cycle.php,The geological carbon cycle,Carbon also moves between rocks and minerals, seawater, and the atmosphere. Carbon dioxide (CO2 ) in the atmosphere reacts with some minerals to form the mineral calcium carbonate

7、 known as limestone.,Illustration by Robert Simmon NASA,Natural Sources and Sinks of Carbon Dioxide,The natural “carbon cycle” includes carbon dioxide used in plants during photosynthesis and the exchange of carbon dioxide between the atmosphere and the oceans. The primary natural processes that rel

8、ease CO2 into the atmosphere (CO2 sources) and that remove CO2 from the atmosphere (sinks) are: Animal and plant respiration, by which oxygen and nutrients are converted into CO2 and energy, and plant photosynthesis by which CO2 is removed from the atmosphere and stored as carbon in plant biomass; O

9、cean-atmosphere exchange, in which the oceans absorb and release CO2 at the sea surface; and Volcanic eruptions, which release carbon from rocks deep in the Earths crust (this source is very small).,The global carbon cycle. This schematic representation shows the global carbon reservoirs in gigatonn

10、es of carbon (1GtC = 1012 kg) and the annual fluxes and accumulation rates in GtC/year, calculated over the period 1990 to 1999. The values shown are approximate and considerable uncertainties exist as to some of the flow values. (.au),Human-Related Sources and Sinks of Carbon Dioxi

11、de,A variety of human activities lead to the emission (sources) and removal (sinks) of carbon dioxide (CO2): The largest source of CO2 emissions globally is the combustion of fossil fuels such as coal, oil and gas in power plants, automobiles, industrial facilities and other sources. Industrial proc

12、esses can also lead to CO2 emissions. Carbon sequestration is the process by which growing trees and plants absorb or remove CO2 from the atmosphere and turn it into biomass (e.g., wood, leaves, etc.). Deforestation, conversely, can lead to significant levels of CO2 emissions in some countries. Carb

13、on dioxide can be captured from power plants and industrial facilities before it is released into the atmosphere, and then injected deep underground. Source: U.S. Greenhouse Gas Emissions Inventory,References,Bureau of Meteorology (BOM) (2011) Climate BOM viewed 28/2/2011 at .au/climate/

14、Dept. Of Climate Change and Energy Efficiency (2011) Tackling the Challenge of Climate Change, Dept. Of Climate Change and Energy Efficiency viewed 28/2/2011 at .au/ Department of Ecology, Washington. (2011) Climate Change. Washington viewed 28/2/2011 at NASA (201

15、1) Earth Observatory the Carbon Cycle, NASA Goddard Space Flight Centre viewed 28/2/2011 at /Features/CarbonCycle/carbon_cycle.php Environment Protection Authority, Victoria (2011) Climate Change, EPA, Melbourne viewed 28/2/2011 at .au/climate-change Environment Protection Authority United States (EPA US), Climate Cha