14. Nutrients Cycle Flashcards
What is a nutrient cycle?
the phases nutrients go through while existing in an ecosystem
keeping track of the elements and molecules as they cycle through
Where does the biomass of a forest come from?
the air -> photosynthesis
(energy is used as a tool in this process)
water / soil too
What is the first law of thermodynamics (sort of)?
conservation of energy/mass
in a chemical reaction, mass is neither created nor destroyed
(atoms/molecules are rearranged and recycled, everything is accounted for)
What is the difference between energy flow and nutrient cycle?
energy can get lost in the flow, but nutrients are a circular economy (they never go away)
How does nutrient cycling pertain to biodegradable items?
biodegradable: eaten by microbes (a part of the cycle), then decomposed into molecules or atoms and then reused
if something isn’t biodegradable, it could be around ‘forever’
the stuff we make may never go away (even recyclable items)
MOST OF OUR POLLUTION PROBLEMS ARE LINKED TO ‘NUTRIENT’ CYCLING OR NOT CYCLING
What are pollution problems in Canada?
greenhouse gasses, acidic precipitation, chlorofluorocarbons, eutrophication
How can humans affect nutrient cycles?
we can create imbalances in the cycles
What is bio-magnification?
the process by which pollutants or chemicals become more concentrated as they move up the food chain
brings together nutrient cycling and energy flow
How does bio-magnification happen?
when ingestion > excretion, chemicals increase in the body over time
typically from fat-soluble compounds, this makes the pollutants more susceptible to transfer because they are better absorbed
when a polluted organism is eaten the pollutants are passed up the food chain
Who is Rachel Carson and what did she do?
she began the modern environmental movement and added a nutrient cycling perspective to our eco-centric ethic
inspired a tighter control on pesticides, specifically DDT
What is the first major environmental success story in North America?
the banning of DDT
bald eagles were endangered in 1967, but not at risk in 2007 due to the ban
What limits primary production in aquatic ecosystems?
nutrients limit our production (not sunlight, even though it’s important)
limiting nutrient in oceans: nitrogen
limiting nutrient in freshwater: phosphorous
Where does phosphorous come from?
it just gets recycled
we make fertilizers out of it which can run-off into freshwater and impede on its nutrient cycling (more than 50% of P from fertilizer ends up in water)
phosphorous can also come from sewage and get into freshwater
What happens when there is too much P in freshwater?
eutrophication: occurs when the environment becomes enriched with nutrients, increasing the amount of plant and algae growth
harmful algal blooms, dead zone, and dead fish
Who makes organic nitrogen?
it makes up 80% of the air, but that N is unavailable
all ‘available’ N was “fixed” by bacteria until the 20th century
we now make an equal amount of N per year as bacteria
