L3 Nutrients and water Flashcards
what is MRT
mean residence time, the time a molecule remains in a single pool, focuses on flux rate, what is the rate of change of a pool
what is the overview of water availability
97% saltwater
3% freshwater (some of it in glaciers)
0.95% in terrestrial ecosystems
what are the the different types of main fluxes of water
evaporation, transpiration, precipitation
what are 3 ways in which humans influence water
- change in river discharge (land-use changes, water diversion, withdrawal from ground waters)
- change in runoff (Dams, irrigation)
- change in precipitation (release of aeorosols into the atmosphere, which increases cloud condensation rates)
how are nutrients released into an ecosystem (5)
through weathering, atmospheric, fixation, biomass and anthropogenic
what is the ratio of assimilation of C in aquatic and terrestrial systems
50/50 (100PgC/yr)
what is the ratio of plant versus marine microorganisms in terms of photosynthetic C biomass
81% plant, 19% microorganisms
what are the 3 main pool of carbon and what is their rough MRT
terrestrial soil (38days)
marine waters (coast 3 years, open ocean 500 years)
ocean sediment (500 years plus)
what is the general trend in terrestrial ecosystems in C fixing since industrial revolution
more C fixed/stored now
what is soil respiration and how much of total ecosystem respiration does it represent
measures amount of CO2 released from the soil, soil respiration is about 50-70% of all ecosystem respiration
what is soil respiration dependent on
rhizosphere, scales positively with NPP and GPP, also dependent on moisture and temperature
what are BVOCs, what do they do and give an example of a BVOC
Biogenic volatile organic compounds - chemicals released by plants (hormones) which affect the residence of other GHGs and induce cloud cover
how is DIC (dissolved inorganic carbon) and DOC (dissolved organic carbon) lost from terrestrial systems
leaching and erosion
what is the change in C cycle since industrial revolution in marine ecosystems?
ocean used to be a source of carbon, now it is a sink, therefore the net flux has changed
what are some type of pumps which release C into the ocean
solubility (gaseous CO2 to DIC)
biological (autotrophs and heterotrophs)
carbonate (organisms with calcium carbonate)
what are some ways human influence carbon cycling
anthropogenic emissions grew and continue to grow
fossil fuels and cement production
land use changes, decrease of green cover
what are the main stores of N
atmosphere, sediment, surface ocean, soil
what was the net flux like in preindustrial era
fixation was equal to denitrification, now fixation is higher than denitrification, N inputs have doubled in the last 2 centuries
what do NOx compounds do
they are harmful air pollutants, come in several forms (eg acid rain)
what is the consequence of the discovery of the Haber-Bosch process
higher rates of eutriphication
what has been the increase in input of P into ecosystems
950%
what are the sources of P
mining, weathering, atmospheric dust and soil erosion
what is P transfer in terrestrial ecosystems dependent on
mycorrhizal interactions
what is the P transfer in marine ecosystems dependent on
run off and atmospehric dust (eg from the Sahara into the oceans)
what is the main driver of eutriphication
P because it is usually the limiting factor
what is the microplast volume comparison in soil sand in oceans
4-23x higher in soils
what is the plastiisphere
a human-made ecosystem consisting of organisms able to live on plastic waste
how are plastispheres different from other microbial communities
selection for photoautotrophs, hydrocarbon degrading bacteria and nitrogen fixers, higher number of mathogenic microorganisms, increase in nitrogenases and antimicrobial resistance genes, multidrug resistant E.Coli
why are microbes attracted to microplasts
functional groups that attract them
what is the effect of presence of microplasts on fungal communities in soil
decrease
what does the characteristic of adsorption of microplasts do
it increases concentration (adsorption) of pollutants, hevay metals and pesticides in ecosystems
what are some general effects of presence of microplastics
- change in soil structure, lower permeability and higher evaporation
- alter sedimentation rates in aquatic systems
- more irrigation needed in agriculture
- higher C influc, inhibit decomposition of organic matter
- shade phytoplankton
- higher nitrification in soil because of aeration but denitrification in marine plastispleres due to anoxic (no DO) conditions
what is the effect of plastic pollution on C pools
microbial frustration - microorganisms prefer to break down plastic C
priming effect - influx of C stimulates metabolism which further breaks down plastic derived and organic C, increase CO2 emissions by 26%, therefore higher rate of C cycling
what are the effects of plastic pollution on N and P pools
stable until 25:1 C:N or 106:16:1 C:N:P
why does AI consume large quantities of water and why is it a problem
AI models reuire large scale data centers which require a lot of water for cooling
eg in Google, the majority is drinking water
what is the carbon footprint of AI
training AI models requires a lot of computational power, shich means high CO2 emissions
