L3 Nutrients and water

Question 1

what is MRT

Answer 1

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

Question 2

what is the overview of water availability

Answer 2

97% saltwater
3% freshwater (some of it in glaciers)
0.95% in terrestrial ecosystems

Question 3

what are the the different types of main fluxes of water

Answer 3

evaporation, transpiration, precipitation

Question 4

what are 3 ways in which humans influence water

Answer 4

• 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)

Question 5

how are nutrients released into an ecosystem (5)

Answer 5

through weathering, atmospheric, fixation, biomass and anthropogenic

Question 6

what is the ratio of assimilation of C in aquatic and terrestrial systems

Answer 6

50/50 (100PgC/yr)

Question 7

what is the ratio of plant versus marine microorganisms in terms of photosynthetic C biomass

Answer 7

81% plant, 19% microorganisms

Question 8

what are the 3 main pool of carbon and what is their rough MRT

Answer 8

terrestrial soil (38days)
marine waters (coast 3 years, open ocean 500 years)
ocean sediment (500 years plus)

Question 9

what is the general trend in terrestrial ecosystems in C fixing since industrial revolution

Answer 9

more C fixed/stored now

Question 10

what is soil respiration and how much of total ecosystem respiration does it represent

Answer 10

measures amount of CO2 released from the soil, soil respiration is about 50-70% of all ecosystem respiration

Question 11

what is soil respiration dependent on

Answer 11

rhizosphere, scales positively with NPP and GPP, also dependent on moisture and temperature

Question 12

what are BVOCs, what do they do and give an example of a BVOC

Answer 12

Biogenic volatile organic compounds - chemicals released by plants (hormones) which affect the residence of other GHGs and induce cloud cover

Question 13

how is DIC (dissolved inorganic carbon) and DOC (dissolved organic carbon) lost from terrestrial systems

Answer 13

leaching and erosion

Question 14

what is the change in C cycle since industrial revolution in marine ecosystems?

Answer 14

ocean used to be a source of carbon, now it is a sink, therefore the net flux has changed

Question 15

what are some type of pumps which release C into the ocean

Answer 15

solubility (gaseous CO2 to DIC)
biological (autotrophs and heterotrophs)
carbonate (organisms with calcium carbonate)

Question 16

what are some ways human influence carbon cycling

Answer 16

anthropogenic emissions grew and continue to grow
fossil fuels and cement production
land use changes, decrease of green cover

Question 17

what are the main stores of N

Answer 17

atmosphere, sediment, surface ocean, soil

Question 18

what was the net flux like in preindustrial era

Answer 18

fixation was equal to denitrification, now fixation is higher than denitrification, N inputs have doubled in the last 2 centuries

Question 19

what do NOx compounds do

Answer 19

they are harmful air pollutants, come in several forms (eg acid rain)

Question 20

what is the consequence of the discovery of the Haber-Bosch process

Answer 20

higher rates of eutriphication

Question 21

what has been the increase in input of P into ecosystems

Answer 21

950%

Question 22

what are the sources of P

Answer 22

mining, weathering, atmospheric dust and soil erosion

Question 23

what is P transfer in terrestrial ecosystems dependent on

Answer 23

mycorrhizal interactions

Question 24

what is the P transfer in marine ecosystems dependent on

Answer 24

run off and atmospehric dust (eg from the Sahara into the oceans)

Question 25

what is the main driver of eutriphication

Answer 25

P because it is usually the limiting factor

Question 26

what is the microplast volume comparison in soil sand in oceans

Answer 26

4-23x higher in soils

Question 27

what is the plastiisphere

Answer 27

a human-made ecosystem consisting of organisms able to live on plastic waste

Question 28

how are plastispheres different from other microbial communities

Answer 28

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

Question 29

why are microbes attracted to microplasts

Answer 29

functional groups that attract them

Question 30

what is the effect of presence of microplasts on fungal communities in soil

Answer 30

decrease

Question 31

what does the characteristic of adsorption of microplasts do

Answer 31

it increases concentration (adsorption) of pollutants, hevay metals and pesticides in ecosystems

Question 32

what are some general effects of presence of microplastics

Answer 32

* 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

Question 33

what is the effect of plastic pollution on C pools

Answer 33

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

Question 34

what are the effects of plastic pollution on N and P pools

Answer 34

stable until 25:1 C:N or 106:16:1 C:N:P

Question 35

why does AI consume large quantities of water and why is it a problem

Answer 35

AI models reuire large scale data centers which require a lot of water for cooling eg in Google, the majority is drinking water

Question 36

what is the carbon footprint of AI

Answer 36

training AI models requires a lot of computational power, shich means high CO2 emissions