6.7-6.9 Flashcards
(28 cards)
What are the factors that lead to the seasonal variation of CO2 concentrations in the atmosphere?
- [CO2] = ↑ in winter bc…dead plant matter decomposes
- [CO2] = ↓ in summer bc…CO2 is taken up by photosynthesis
Which human activities contribute to the steady increase in average atmospheric CO2 concentrations?
- Fossil fuel consumption, cement production, deforestation
- 8.0 Gt C/year of CO2 = emitted from fossils/land use changes (mainly deforestation)
What are the major pools of carbon in the global carbon cycle and processes that move carbon from one pool to another?
- Major pools = carbon in air, soil, biomass and oceans
- Drivers of exchange b/w air and biosphere = cycles of respiration/photosynthesis, absorption/outgassing from oceans
How does the ocean take up CO2? Why doesn’t the ocean serve as an infinite sink for CO2?
- Because the ocean water is alkaline and CO2 acidic = CO2 reservoir
- Not an infinite sink bc only top 75 m = exchanges w/ atmosphere and as CO2 is absorbed, it is uses up available alkalinity by forming carbonate ions = slowing CO2 uptake
What are some factors that make it hard to estimate and predict the amount of carbon stored in the biosphere?
- Storage could ↑ from fertilizing (↑ CO2 in atmosphere = (↑ plant growth)
- BUT nitrogen, phosphorous, and water may be limiting resources for ↑ biomass production
- ↑ temps = ↑ rates of respiration = > rate of photosynthesis could create net carbon loss
- If global warming rapidly shifts climates, could cause major forest die-offs
preindustrial [CO2]=
280 ppm
current [CO2] =
390 ppm
Reservoir
region of environment that holds significant maount of material
- Physically or chemically separated from other reservoirs
Flows
how much material is transferred from 1 reservoir/time
Steady state
inflows = outflows
Residence times
average length of time material spends in reservoir
- Ratio of: reservoir size/inflow or outflow rate
How do you determine the mass of material in a reservoir?
Mass = (concentration of material obtained in sample)*(size of reservoir)
Methane
main constituent of natural gas deposits
methane production
Produced by microbes living in anaerobic conditions
Aerobic microbes use CH4 as energy source =
↓ CH4 in atmosphere
Microbial sources:
forestomaches of ruminant animals, termite colonies, wetlands, rice paddies, manure piles, landfills
Reduction of methane =
Δs to rice cultivation, collection of CH4 from landfills, better manure management
does co2 or ch4 release have a greater impact for climate change?
CH4
ch4 and permafrost feedback loop
- ↑ CH4 from climate change = ↑ released from seafloor and permafrost
- As ↑ water temp = ↑ CH4 release
Where do methane deposits come from?
Produced by microbes living in anaerobic conditions
- Microbial sources: forestomaches of ruminant animals, termite colonies, wetlands, rice paddies, manure piles, landfills
What are some natural processes that remove methane from the atmosphere?
- Oxidation w/in troposphere by OH (hydroxyl radical)
- Aerobic microbes use CH4 as energy source = ↓ CH4 in atmosphere
What is the main process that leads to the release of N2O to the atmosphere?
Denitrification- bacteria converts nitrate in soil/water –> N2 and N2O
What is the main source of CFCs?
Refrigerants (or air conditioners)
Nitrification
microbial process reduce nitrogen (ammonia) nitrite/nitrate
