Ecology

1
Ecology

• PART III

2
Recycling Matter

• Lesson Objectives
• Define biogeochemical cycles.
• Describe the water cycle and its processes.
• Give an overview of the carbon cycle and the
  oxygen cycle.
• Outline the steps of the nitrogen cycle.

3
BIOGEOCHEMICAL CYCLES

• bio- biotic components
• geo- geological and abiotic components

4
WATER CYCLE
5
Evaporation, Sublimation, and Transpiration

• Sun drives the water cycle.
• Heats oceans, lakes, and other bodies of
• water.
• Heated water evaporates.
• Evaporation
• Heats ice and snow.
• Heated ice and snow turns into water vapor.
• Sublimation
• Heat causes plants to release water through their
  stomata (pores in leaves)
• Transpiration

6
Condensation and Precipitation

• Rising air currents
  carry water
• from evaporation,
  sublimation,
• and transpiration into
  the
• atmosphere.eventually
  
• forming CLOUDS

7
Groundwater and Runoff

• Rain falls on land and soaks
• into ground infiltrating and
• becomes groundwater
• Or rain falls on land and flows
• over it
• Runoff ends up in bodies
• of water

8
CARBON CYCLE

• Carbon in rocks is dissolved by water and ends up
  in oceans
• Other carbon from burned fossil fuels or their
  by-products ends up in the atmosphere or
  biosphere
• Note fossil fuels are
• formed from the
• remains of dead
• organisms

9
Carbon in the Atmosphere

• Living organisms release carbon dioxide as a
  byproduct of cellular respiration.
• Carbon dioxide is given off when dead organisms
  and other organic materials decompose.
• Burning organic material, such as fossil fuels,
  releases carbon dioxide.
• When volcanoes erupt, they give off carbon
  dioxide that is stored in the mantle.
• Carbon dioxide is released when limestone is
  heated during the production of cement.
• Ocean water releases dissolved carbon dioxide
  into the atmosphere when water temperature rises.
  
• From methane gases released from landfills

10
Carbon in the Ocean Water

• Most comes from atmospheric carbon dioxide
  that dissolves in ocean water thus forming
  carbonic acid. (in cooler water)
• The process is reversible in warmer water
  changing carbonic acid to bicarbonate ions
• Bicarbonate ions are also deposited into oceans
  from runoff
• Carbonic acid ?H2CO3
• Bicarbonate ions ? HCO3-

11
Carbon in the Biosphere? organic pathway

• Photosynthetic algae and bacteria take up
  bicarbonate ions in the ocean use it to
  synthesize organic compounds
• Terrestrial autotrophs remove carbon dioxide from
  the atmosphere to synthesize organic compounds
• Both recycle it back through a process called
  cellular respiration
• Decomposers release carbon dioxide when they
  consume dead organisms
• They rates of exchange are about equal

12
Carbon in Rocks and Sediments(geological pathway)

• Long, slow process through rock formation,
  subduction, and volcanism
• In oceans begins as sedimentary rock pressure of
  additional layers forms the rock

13
Oxygen Cycle

• Movement of oxygen through the atmosphere,
  biosphere, and the lithosphere.

14
Oxygen and the Hydrosphere

• Failures in this type of movement development
  of hypoxic (low oxygen) zones or dead zones
• Cause excessive nutrient pollution from human
  activities that lead to depletion of oxygen
  required to sustain marine life

15
Oxygen and the Biosphere/Atmosphere

• Free oxygen in the biosphere (0.01) and
  atmosphere (0.36).
• The main source of atmospheric free oxygen is
  photosynthesis. Photosynthesizing organisms
  include the plant life of the land areas as well
  as the oceans.
• Additional source of atmospheric free oxygen
  comes from photolysis

16
Oxygen and the Lithosphere

• Largest reservoir of Earth's oxygen is within the
  silicate and oxide minerals of the crust and
  mantle (99.5).

17
NITROGEN CYCLE

• Most nitrogen is stored in the atmosphere (78
  nitrogen gas)
• Nitrogen moves through abiotic and biotic
  components of ecosystems

18
Absorption of Nitrogen

• Plants and producers make nitrogen-containing
  organic compounds (chlorophyll, proteins, nucleic
  acids)
• Plants absorb nitrogen from
• the soil through their root hairs
• in the from of nitrate ions
• Nitrogen is changed in the soil
• through nitrogen fixation into
• nitrate ions
• Nitrate ions ? NO3-

19
Nitrogen Fixation

• 
  Nitrogen-fixing bacteria
• live in
  soil or in the root
• nodules
  of legumes
• In
  aquatic system, some
• 
  cyanobacteria fix
• nitrogen
• Nitrogen gas in the atmosphere can also be fixed
  by lightning
• Some nitrogen is converted into fertilizer by
  humans

20
Ammonification and Nitrification

• Decomposers break down organic remains and
  release nitrogen in the form of ammonium ions
• Ammonification
• Certain soil bacteria convert the ammonium ions
  into nitrites. Others convert the nitrites into
  nitrates that
• plants can absorb
• Nitrification
• Ammonium ions ?NH4-
• Nitrites ? NO2-
• Nitrates ? NO3

21
Denitrification and the Anammox Reaction

• Denitrifying bacteria in soil convert some
  nitrates back to nitrogen gas ? NO2
• Denitrification
• In aquatic systems, bacteria in the water convert
  ammonium and
• nitrite ions to water
• and nitrogen gas
• - Anammox Reaction

22
Lesson Summary

• Chemical elements and water are recycled through
  biogeochemical cycles. The cycles include both
  biotic and abiotic parts of ecosystems.
• The water cycle takes place on, above, and below
  Earths surface. In the cycle, water occurs as
  water vapor, liquid water, and ice. Many
  processes are involved as water changes state in
  the cycle. The atmosphere is an exchange pool for
  water. Ice masses, aquifers, and the deep ocean
  are water reservoirs.
• In the carbon cycle, carbon passes among
  sedimentary rocks, fossil fuel deposits, the
  ocean, the atmosphere, and living things. Carbon
  cycles quickly between organisms and the
  atmosphere. It cycles far more slowly through
  geological processes.
• The oxygen cycle produces most available oxygen
  through photosynthesis by plants on land and
  phytoplankton on the oceans surface. Some oxygen
  is made in the atmosphere when sunlight breaks
  down atmospheric water. Oxygen is used by both
  biotic and abiotic factors in ecosystems
  plants, animals, bacteria, decomposition, fire,
  and oxidizing agents
• The nitrogen cycle moves nitrogen back and forth
  between the atmosphere and organisms. Bacteria
  change nitrogen gas from the atmosphere to
  nitrogen compounds that plants can absorb. Other
  bacteria change nitrogen compounds back to
  nitrogen gas, which re-enters the atmosphere.