Title: Geochemical Cycles
1Geochemical Cycles
2Water Cycle
Evaporation water changing from liquid form to
gas
- Movement of water among ocean, atmosphere, and
land. - Enters atmosphere through evaporation and
transpiration (plant leaves)
Transpiration plant leaves losing water to the
atmosphere
Hurricane Katrina approaches
3Geochemical Cycles
- Water Cycle
- When air is warmed up, the particles get farther
apart (and so have lower density). - H20 rises in columns of warm air and may remain
in atmosphere for about 2 weeks. - As the H20 vapor rises, it cools into droplets
(condenses), forming clouds
Condensation water vapor transforming into
liquid water. Occurs because cooler air does not
have as much space to hold water vapor.
4Water Cycle
Runoff any water moving across the land
- Enters land through precipitation and
condensation. - Enters lakes or rivers through runoff
- Enters groundwater where it enters the biosphere.
Groundwater any water stored underground!
When water vapor in the air cools (usually at
night), it condenses on grass (dew) or in the air
(fog).
5SUN
WATER CYCLE
Precipitation
Precip and Conden
Movement of water vapor by wind
Mountains
Evaporation Transpiration
Run Off
Streams
LAKES
Evaporation
OCEANS
Aquifer
Groundwater
6Humans affect the water cycle
- Higher global temperature increased evaporation.
- Higher ocean temps increase evaporation
- Reduction in rainforest reduces transpiration.
- Reduction of plant life increases runoff
- Glacial melting reduces amount of reflected light
7Geochemical Cycles
- Carbon Cycle
- Early atmosphere of Earth 95 CO2. Photosynthetic
plants removed some of the CO2 and added O2.
Todays atmosphere is 0.04 CO2! - Reactions of photosynthesis and cellular
respiration couldnt take place without carbon.
These two reactions form a continuous cycle. - Two important sources of Carbon are the ocean
(since CO2 dissolves easily in H20) and rocks
(such as coal, ore and limestone formed from dead
organisms)
Carbon is found in the atmosphere primarily as CO2
Photosynthesis Plants taking CO2 out of the
atmosphere and using it to produce sugar.
Cellular Respiration Organisms take that sugar
and in the process of burning energy release CO2
back into the atmosphere.
8(No Transcript)
9And, another way to look at the carbon cycle
10Humans affect the Carbon Cycle
- Burning of fossil fuels, (oil, coal and natural
gas). - Fossil fuels were formed very long ago and is
fixed essentially locked out of the carbon
cycle. - By burning fossil fuels the carbon is released
back into the cycle.
11Humans affect the Carbon Cycle
- We presently release more carbon into the air
than can be reabsorbed by photosynthetic
organisms, thereby we have a net INCREASE of
carbon in the cycle. - This atmospheric carbon has a role to play in the
warming of the atmosphere.
12Geochemical Cycles
- Nitrogen Cycle
- Organisms require Nitrogen to form amino acids
for the building of proteins. - Lots of N2 in our atmosphere
- Unfortunately, most organisms CANNOT use
atmospheric nitrogen. - Nitrogen-fixing bacteria CAN use N2 from the
atmosphere.
Nitrogen-fixing bacteria convert atmospheric N2
into ammonia (NH4) which is a form of nitrogen
that plants CAN use.
13Nitrogen Cycle Continued
- Nitrogen-fixing bacteria live in the soil and in
roots of legumes. - These bacteria also form nitrites (NO2) and
nitrates (NO3) which are compounds containing N
and O. - Nitrate is the most common source of N for
plants. - Animals get N from the proteins they eat.
- Decomposers return N to the soil in the form of
ammonia and the cycle repeats. - So, oftentimes, the nitrogen cycle does not
require the N to be returned to atmospheric form!
14Nitrogen Cycle Summary
- All living organisms require nitrogen to form
amino acids to build proteins. - Proteins are important for locomotion,
reproduction, defense, and structure. - Nitrogen makes up 78 of atmosphere as N2
- Nitrogen-fixing bacteria are very important - N2
needs to be fixed before it can be used by most
living things.
15NITROGEN CYCLE
N2
Fertilizer Production
Lightning
Denitrification
(GAS)
Nitrogen Fixation
Crops
Legume
Nitrogen-Fixing Bacteria in soil roots
Decomposers
Ammonia Nitrates Nitrites
16(No Transcript)
17Humans affect the Nitrogen Cycle
- From the production and use of nitrogen
fertilizers to the burning of fossil fuels in
automobiles, power plants, and industries, humans
impact this cycle. - Nitrogen is essential to living organisms and its
availability plays a crucial role in the world's
ecosystems. - Excessive nitrogen additions can pollute
ecosystems
18Humans affect the Nitrogen Cycle
- Increased global concentrations of nitrous oxide
(N2O), a potent greenhouse gas, in the atmosphere
- Increased concentrations of nitric oxide, (NO)
that drive the formation of smog along with N2O - Losses of soil nutrients such as calcium and
potassium that are essential for long-term soil
fertility
19Humans affect the Nitrogen Cycle
- Acidification of soils and of the waters of
streams and lakes - Greatly increased transport of nitrogen by rivers
into estuaries and coastal waters where it is a
major pollutant.