Transcript Geochemical Cycles

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.
The Greenhouse Effect
Section 4-1
Sunlight
Some heat
escapes
into space
Greenhouse
gases trap
some heat
Earth’s surface
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/earthg
uide/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.