CYCLES OF THE ENVIRONMENT

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CYCLES OF THE ENVIRONMENT

• 4 CYCLES THAT MAINTAIN HOMEOSTASIS IN THE
  ENVIRONMENT

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Our Environments Homeostasis

• Atoms of carbon, hydrogen, nitrogen, oxygen and
  phosphorous make up living
• organisms (CHNOPS)
• This matter AND energy recycles through
  ecosystems.

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Matter Energy Transfer through Environment

• Food Chain

• Food Web

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Cycling Maintains Homeostasis

• Food chains, food webs and energy pyramids ?
  energy gained or used in one direction in
  ecosystem.
• Matter, in form of nutrients, moves through org.
  at each trophic level.
• Trophic Levels include producer, lst order
  consumer, 2nd order consumer

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Food Chain Energy Pyramid

• Energy Pyramid

• Food Chain

Quaternary-4th
Tertiary-3rd
Secondary-2nd
Primary-1st
Producer
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Energy Flow in an Ecosystem

• Each step in a food
• chain represents a transfer of energy
  materials.
• Energy is lost at each level only 10 is
  transferred to next trophic level.

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Energy Loss at Trophic Levels

• 90 of Energy is used by the organism for
• Breathing /Respiraton
• Reproduction
• Homeostasis
• Movement/Interaction with other orgs.

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4 Cycles of an Environment

• They include
• Water Cycle
• Carbon Cycle
• Nitrogen Cycle
• Phosphorous Cycle

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Water Cycle 3 states of Matter

• 1. liquid (water or precipitation),
• 2. solid (ice, snow)
• 3. Gas (atmosphere)

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WATER CYCLE
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Water Cycle Flow

• Water begins cycle through ecosystem when plants
  absorb water through roots.
• Animals drink water or get it indirectly w/food
  they consume.
• Animals and plants respire giving off water vapor
  (Transpiration).

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Water cycle (continued)

• Organisms lose water through excretion.
• Water (liquid, solid or gas) recycles into lakes,
  streams, rivers, oceans via the
• groundwater.

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Carbon cycle

• 1. Carbon found in environment as a gas
• (CO2) in atmosphere and oceans.
• 2. CO2 moves to water and plants.
• Photosynthesis is major player in CC.
• a. P.S. combines carbon dioxide and water.
• b. P.S. changes molecules fr low energy to high
  energy.

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CARBON CYCLE

1. Org. obtain carbon when they consume producers or
   other consumers.
2. Respiration and decay return carbon to the
   atmosphere (gas).
3. Carbon also returns to atmosphere in large
   amounts as CO2 when fossil fuels are burned.

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Carbon Cycle
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Nitrogen Cycle - Land

• N2 makes up 78 of air.
• Living things cannot use Nitrogen in
• atmospheric form.

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Nitrogen moves through the food web.

• Nitrogen cycles as matter and energy transfer
  through the food web.

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Nitrogen Fixation Methods

• Conversion of atmospheric N2 into reactive
  compounds such as
• Biological Fixation
• Abiotic Fixation
• Denitrification
• Assimilation
• Nitrification
• Ammonification

Nitrogen Forms BADANA
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Nitrogen Compounds

• N2 Nitrogen
• NO2 nitrogen oxide or nitrite
• NO3-Nitrous oxide or nitrate
• NH3 Ammonia
• NH4 - Ammonium

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Nitrogen Cycles
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1. Abiotic Fixation

• High energy fixation w/ lightning cosmic
  radiation. Accounts for 10 of nitrate in N2
  cycle. Occurs when
• 1. N2 combines w/O2 to form nitrogen oxides such
  as NO and NO2
• 2. Carried to Earths surface in rainfall as
• nitric acid (HNO3 or acid rain).

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Legumesyou say?

• A legume is any of the thousands of plant species
  in the legume family, Leguminosae.
• Legumes have seed pods that, when ripe, split
  along both sides.

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2. Biological Fixation

• Completed by living orgs such as
• soil aerobic bacteria (needs O2) and anaerobic
  bacteria (chemosynthesis w/o O2).
• b. Symbiotic bacteria (Rhizobium) found in roots
  of legumes such as clover, alfalfa, soy beans and
  chick peas assists in bio fix.

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Soybeans and Chickpeas

• Chick Peas

• Soy Beans

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2. Biological Fixation (cont)

• How does this happen?
• c1. Roots of legumes, bacteria split the
  nitrogen atoms into two free nitrogen atoms which
  combine with hydrogen to form ammonia, NH3.
• c2. Any excess nitrogen leftover from
  ammonification (NH3) not used by the plant are
  returned to the soil.

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2. Biological Fixation (Cont)

• Some bacteria freely fix nitrogen, without
  splitting the N2 atom, in soil such as
• 1. Aerobic bacteria, Azotobacter
• 2. Anaerobic bacteria, Clostridium
• 3. Photosynthetic Cyanobacterium fix
• nitrogen in aquatic environments.

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Major agricultural crops produced in the United States in 2000 (excluding root crops, citrus, vegetable, etc). Major agricultural crops produced in the United States in 2000 (excluding root crops, citrus, vegetable, etc). Major agricultural crops produced in the United States in 2000 (excluding root crops, citrus, vegetable, etc).
Crop Harvested Area (million acres) Cash Receipts from Sales ( billion)
Corn (grain) 72.7 15.1
Soy-beans 72.7 12.5
Hay 59.9 3.4
Wheat 53.0 5.5
Cotton 13.1 4.6
Sorghum (grain) 7.7 0.82
Rice 3.0 1.2
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2. FYI Benefits of N2 Fix

• Since its introduction into Nigeria in 1908,
  soybean (Glycine max. (L) Merrill) has been grown
  primarily as a sole crop (Ogunwolu, 1991) yet it
  has been shown to be able to fix atmospheric
  nitrogen up to 417 kg N ha-1
• (LaRue and Patterson, 1981)

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2. Biological Fixation (cont)

1. To promote sustainable soil fertility, it is
   beneficial to use these legume crops w/other
   plants such as corn.
2. Corn depletes the available N2 in soil quickly.

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3. Nitrification

• Nitrification is a process of nitrogen compound
  oxidation (effectively, loss of electrons from
  the nitrogen atom to the oxygen atoms)see next 2
  slidescaused by Bacteria.

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Nitrifying Bacteria
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3. Nitrification

• NH3 is oxidized to nitrite ions (NO2) and then
  to nitrate ions (NO3).
• Bacteria, Nitrosomas. oxidizes NH3 to NO2.
• (NH3 1.5 O2 Nitrosomonas ? NO2- H2O H)
• NO2- 0.5 O2 Nitrobacter ? NO3-

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3. Nitrification

• Bacteria, Nitrobacter, oxidizes NH3 to NO3.
• NH3 O2 ? NO2- 3H 2e-
• NO2- H2O ? NO3- 2H 2e-

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4. Assimilation-Plants

1. Nitrates (NO3) are commonly assimilated (taken
   in/absorbed) by plants through their root hairs.
   

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4. Assimilation-Heterotrophs

• b. Heterotrophic organisms cannot readily absorb
  N2 as plants do, so N2 is acquired through foods
  they/we eat.

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4. Assimilation (cont)

• c. Plants are base of food chain.
• d. N2 is already assimilated into their tissue
  will continue to pass from one organism to
  another.

Food Chain
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5. Ammonification

• a. Host of decomposing microorganisms such as
  bacteria fungi breaks down nitrogenous wastes
  organic matter found in animals and dead plants.
• b. It is converted to inorganic NH3 for
  absorption by plants as ammonium ions (NH4).

• c. Decomposition rates affect the level of
  nutrients available to primary producers.

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5. Ammonification
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6. Denitrification

• Nitrates (NO3) are reduced to N2 and are lost /
  returned to the atmosphere.
• Facultative anaerobes in anaerobic conditions
  break down the NO3s.

• c. Ex Farmers w/waterlogged fields and
  high-clay content are vulnerable to losing the
  available nitrogen for their crops.

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Phosphorous cycle
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Phosphorous Cycle

• 2 ways Short-term and Long Term
• A. Short-term
• Plants use P from soil in body tissues.
• Animals get phosphorous fr eating plants.
• When animals die, they return the
• P to the environment.

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Phosphorous Cycle

• Long Term Phosphorous Cycle
• Phosphates washed into the oceans b/c part of
  rock compounds.
• After millions of years, rock layers wash off and
  P b/c part of the environment.