Download Cycling in the Ecosystem

Cycling in the Ecosystem
PAGES 371-374
Ecosystem
Review: What is an ecosystem?
•Ecosystem: an environment where the living (biotic) and
non-living (abiotic) things affect one another
•Biogeochemical process: circulation of substances through
living organisms (biotic factors) and the environment
(abiotic factors)
Water Cycle
Water Cycle
•Evaporation: water vapor enter the atmosphere
Water Cycle
•Transpiration: evaporation of water through the leaves of
plants
Water Cycle
•Precipitation: water vapor that leaves the atmosphere (as
rain, snow, sleet, hail, etc)
Water Cycle
Human Effects/Influences:
◦ Building cities prevents water from reaching
groundwater stores (increases runoff)
◦ Pollutants in air mix with water vapor to create acid
rain
Carbon Cycle
Carbon Cycle
•Photosynthesis: converting light energy into organic
compounds (C6H12O6)
•CO2 + H2O  C6H12O6
Carbon Cycle
•Cellular respiration: breaks down sugar to release energy
and CO2 is released into atmosphere
•C6H12O6  CO2 + H2O + ATP
Carbon Cycle
•Combustion: burning of fossil fuels for energy releases CO2
Carbon Cycle
Human Effects/Influences:
◦ Deforestation reduces amount of producers that can
perform photosynthesis
Nitrogen Cycle
Nitrogen Cycle
• 70% of atmosphere is nitrogen (N2), but this nitrogen is not
in a ready to use form
•N2 needs to converted into NH3 (ammonia)
•Nitrogen is an essential component of DNA, RNA, and
proteins
Nitrogen Cycle
•Nitrogen fixation (biological): bacteria convert nitrogen gas
(N2) to usable form, NH3 (ammonia)
Nitrogen Cycle
•Ammonification: decomposers break down wastes (urine,
feces, death) to ammonia (NH3 )
Nitrogen Cycle
•Nitrification: bacteria convert NH3 to nitrates (NO3-). These
are like fertilizers that plants can use.
Nitrogen Cycle
•Assimilation: plants absorb nitrate to make amino acids
(enters food chain)
Nitrogen Cycle
•Denitrification: bacteria return nitrogen to atmosphere
(NO3-  N2)
Nitrogen
Human Effects/Influences:
◦ FERTILIZERS!
◦ Excess nitrogen fertilizer can runoff,
where it contaminates surface water or
infiltrates into ground water.
◦ In drinking water, excess nitrogen can
lead to cancer in humans and respiratory
distress in infants.
Nitrogen
In surface waters, extra nitrogen can lead
to nutrient over-enrichment
This leads to
◦fish-kills
◦harmful algal blooms
◦and species shifts in
aquatic and land
ecosystems