EE22 Flashcards
What molecules did the early atmosphere contain?
CH4 CO2 NH3 H2 N2 H2O * prebiotic molecular soup of aa purines and pyrimidines develop
What is the basis for life?
carbon
What are carbon sources and sinks?
sources -respiration -deforestation -decompisition -burning fossil fuels sink -biomass -sediments
What kind of carbon exchange is biomass at equilibrium?
neither a sink or source
fixation balanced by respiration
biomass couldnt buffer changes in atmospheric C02
What are carbon pools?
solids - rocks and sediments gasses - atmosphere 400ppm now 265ppm pre industrial revolution water clathrates
what is a clathrate?
solids composed of water molecules forming rigid lattic cages
each cage contains 1 molecule of methane
water crystallises into small isometric crystallorgraphic system rather than hexagonal system of normal ice
what is the clathrate gun hypothesis?
energy gun loaded as clathrates build up in cold periods
fun fired cause rapid greenhouse warming
occurs on different time scales ad magnitudes
produce well documented sawtooth pattern of temperature change
what is alochthonos?
denoting sediment or rock that originated at distance from its present position
what is autochthonous?
deposits formed in current position
what human activities cause carbon flux?
Burning
deforestation
CFCs- ozone depleteting
modern agriculture
what are the consequences of increased co2?
immediate increase in photosynthesis of C3 plants, often dissapears after long exposure- suggests homeostasis increased biomass and fruit production 34% water saving for 2X Co2 Root shoots ratio increases N-fixders benefit more than other plants
In which ecosystems might photosynthesis be co2 limited?
C3>C4
increased Co2 is increased water use efficiency
-reduced food quality for herbivores
What is net CO2 assimilation rate at higher termperatures?
higher at higher temps
what are fluxes?
processes that transfer from one pool to another
What is residence time?
looks like a backwards Tau
av. amount of time a particle spends in a particular system
What affect is increasing CO2 levels having on some South African biomass plots?
change in total biomass from 59 plots across SA
show general increase in biomass
- most parsimonious explanation is increase in plant resource availability Co2 increase NPP
mortality is increasing but lagging behind accelerated growth
increase atmos Co2 = fertilizing remote tropical untouched forest
causing carbon sink
C sink =
change in NPP x residence time (J)
(J) = mass/flux
J= yrs
