Geochemical Cycles

Carbon Cycle• All living things are made of carbon. Carbon is also

a part of the ocean, air, and even rocks. Because the Earth is a dynamic place, carbon does not stay still. It is on the move!

Sources*add CO2 to atmosphere•Respiration•Volcanoes•Decomposition of organic matter•Fire•Weathering and Erosion•Combustion of fossil fuels

Sinks

*remove CO2 to atmosphere

•Photosynthesis

•Fossils and fossil

Fuels

•In Oceans, combines

With H to make

Carbonic acid (bad )

                                             

Greenhouse Effect

• Carbon Dioxide, Methane and water vapor in the atmosphere absorb some of the energy of the sun and reflect it back towards the Earth.

• Some of this absorption is natural and life as we know it would not be possible without it.

• The problem is the amount of the gases causing an excessive amount of heat reflected back to the earth.

Greenhouse Effect• Burning of fossil

fuels causes an excessive build up of carbon dioxide (greenhouse gas) in the atmosphere increasing global warming.

SunlightSome heat escapesinto space

Greenhousegases trapsome heat

Atmosphere

Earth’s surface

Section 4-1

The Greenhouse Effect

Atmospheric CO2

Global Warming• Climate change could

lead to famine, floods, new diseases and large movements of populations.

• Alaska is warming at 7 times the rate of the rest of the planet, resulting in bad fire years and propagation of the Spruce Beetle.

Sea Level Rise

• Has been rising at the rate of 1.8 mm a year for the last 100 years.

• Caused by two things; thermal expansion of water and melting of sea ice.

• 10% of the worlds population lives within 10 m of sealevel.

Polar Ice Cap• The Polar Ice Cap has been melting and is

leading to development of ports and shipping in the Arctic Ocean!!! Not good! Thought to endanger polar bears who hunt on ice pack

http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/

The Nitrogen Cycle

4 Processes of Nitrogen Cycle• Fixation – breaks stable nitrogen molecule

apart so it can be attached, done by lightning and bacteria.

• Decay – when plants and animals break down they return their nitrogen to the earth as ammonia.

• Nitrification – conversion of ammonia from waste and decomposition to nitrates that plants must consume to grow (like fertilizer).

• Denitrification – Nitrates are turned back into gas and released to atmosphere.

The Nitrogen Cycle

The Phosphorus Cycle

Phosphorus Cycle

• Important for plants and animals because it is a major constituent of DNA

• Unlike other cycles it does not have a gaseous state at normal temperatures so it cycles through soil, water and sediments.

• Plants pick it up through soil and animals get it from eating plants or eating animals that eat plants.

• Stored in rocks and sediments for millions of years until released by weathering.