Physical geography #4

[notjustacabbie.livejournal.com]

The room is devoid of it's usual maps - instead there are containers of sea water and pieces of coal littering the classroom.

'Further to last week's discussion of hydrology, today's topic continues looking at another aspect of biogeography - the carbon cycle.

Biogeography can be simply defined as the academic study of the factors that control the spatial distribution of organisms. The carbon cycle is the biogeochemical cycle by which carbon is exchanged between the biosphere, geosphere, hydrosphere and atmosphere of the Earth.

All life is based on the element carbon. Carbon is the major chemical constituent of most organic matter, yet by weight, carbon is not one of the most abundant elements within the Earth's crust. Only 0.032 % of the lithosphere is carbon.

Carbon is stored in the following sinks -
Organic molecules in living and dead organisms found in the biosphere
Carbon dioxide in the atmosphere
Organic matter in soils;
In the form of fossil fuels and rock deposits
Dissolved in the oceans.

The carbon cycle models the movement and storage of carbon in the biosphere, lithosphere, hydrosphere and atmosphere. Carbon is stored in the biosphere as living organisms; in the atmosphere as carbon dioxide gas; in the lithosphere as soil organic matter, as fossil fuel deposits, and as sedimentary rock deposits; and in the oceans as dissolved carbon dioxide gas and as calcium carbonate shells in marine organisms. Processes the move carbon from one store to another include photosynthesis, respiration, oceanic diffusion, biomass combustion, fossil fuel burning, fossil fuel creation, and sedimentary rock formation. Humans have altered the carbon cycle through fossil fuel burning, deforestation, and land-use change. The net result of these processes is an increasing concentration of carbon dioxide in the atmosphere.'

With reference to these materials discuss how humans have altered the carbon cycle.

Then complete the following exercise.