Biogeochemical cycles Flashcards
definition of biogeochemical cycle
interlined processes involving living organisms that all materials to be recycled and repeatedly reused (prevents build up of waste)
Name the 3 human actions that affect photosynthesis in the carbon cycle + explain
marine pollution = decrease phytoplankton pop. less CO2 absorbed, more C in atmo.
Afforestation = more photo., less C in atmo.
Deforestation = less photo., increase C in atmo.
Name the 3 biogeochemical cycles
carbon
nitrogen
phosphorus
Name the human action that affects changes to aerobic respiration in the carbon cycle
soil disturbance/ploughing = increase aeration, increase aerobic respiration for organisms, more DOM
Drainage of marshes and destruction of peat bogs lead to…
more CH4 being released into atmo. CH4 oxidised to become CO2
Name 3 human actions that increase CH4 release
Cattle farming, padi fields, anaerobic respiration in landfill
Name 3 knock on effects of climate change on the carbon cycle
melting permafrost = releases CH4, oxidises: CO2
increased temps =
negative feedback: increase rate of photo. decrease carbon
positive feedback: increase decomposition, C released
ocean acidification = more CO2 being dissolved into oceans
Ocean acidification is due to…
carbonic acid being created by CO2 being dissolved in the ocean from any human activity that releases CO2 . More H+ ions = more acidic
name 5 ways to sustainably manage carbon cycle
- alternative to fossil fuels
- conservation of biomass
- carbon sequestration and CCS
- matching afforestation to deforestation
- increasing soil organic matter (main carbon sink of soil)
Name the 2 different pre-combustion tech (CCS)
- gasification = converts fuel into CO2+H. CO2 removed. H used as fuel
- Oxy-fuel combustion systems = combustion of fuel in pure O, only H2O vapour and CO2 produced (easier to separate)
Post-combustion tech (CCS)
removing CO2 from exhausts through 3 different methods
Name the 3 methods of Post-combustion tech (CCS)
- high pressure CH4 filtration
- Dissolving CO2 in solvent
- Cryogenic (low temp) separation
Name the 2 different ways carbon can be stored (CCS)
- normally stored underground i.e. depleted aquifers
2. or used to aid oil recovery (secondary oil recovery)
In the Carbon cycle name 2 processes that are aerobic
plants and animals respiring aerobically. Phytoplankton respiring aerobically
for the carbon cycle: crop removal _______ the amount of DOM
decreases
name at least 2 of the 4 reasons why organisms need nitrogen
to synthesise:
ATP, DNA, Proteins, Chlorophyll
what is nitrogen fixation + what carries it out
- taking atmospheric N into the soil
- Produces ammonia
+ done by nitrogen fixing bacteria
what is ammonification + what carries it out
- decomposition of DOM
- produces ammonia
+ done by decomposers
what is nitrification + what carries it out
- converting ammonia into nitrite then into nitrate
- nitrate absorbed by plants
+ done by nitrifying bacteria
what is denitrification + what carries it out
- reducing nitrate into N and NOx gases
- N released back into atmo.
+ done by denitrifying bacteria
what is leaching
- nitrates leach (soluble so wash out of soil)
- leads to loss of nutrients
- can act as nutrients for aquatic organisms in water bodies
Name the 7 ways humans impact the nitrogen cycle
haber process growing legumes water logging sewage disposal combustion processes drainage/ploughing leaving crop residue after harvest
what is the haber process? and how does it impact the N cycle
- industrial process to produce ammonia for agricultural fertilisers
- artificial fixation of atmospheric N to ammonia
- ammonia can be converted to nitrates
+ increases movement of atmo. N to ammonia/nitrate
How does growing legumes impact N cycle
- legumes have nitrifying bacteria in their root nodules (increase fixation)
+ increase nitrates in soil
How does drainage/ploughing impact N cycle
- aeration of soil
- produces aerobic environment so increase in aerobic processes i.e. fixation and nitrification
- decreases anaerobic processes: less denitrification (less N going to atmo.)
how does sewage disposal impact N cycle
- increase nitrate movements (leaching) into H2O bodies
+ can cause eutrophication: increase algae, reduced O2 as plants beneath algae die due to blocked sunlight, decomposition occurs (O2 depleted even more), produces dead zones
how does combustion processes impact N cycle
- N + O = NOx \+ increase nitrate in soil (when rains) \+ cause photochemical smogs (NOx reacts with UV): increase risks of respiratory infections i.e. asthma/heart disease \+ NOx (greenhouse gas) = global warming \+ NOx toxic and produce acid rain
how does leaving crop residue impact N cycle
addition of nitrates to soil
how does waterlogging impact the N cycle
example: growing rice in padi fields
- increase anaerobic conditions
+ increase denitrification = decrease nitrates in soil
Name all of the aerobic processes in the N cycle
fixation
ammonification
Nitrification
Name all the anaerobic processes in the N cycle
denitrification
name the 4 methods f counteracting anthropogenic N movements
reduced combustion processes
use of natural fixation processes (instead of haber)
management of biological waste
methods to reduce soil nitrate leaching
how does reduced combustion processes counteract N movements
- reduce use of fossil fuels = less NOx release
+ done by depleting fossil fuel supplies and switching to renewable energy - use of circular economy principles (polymers produced by living organisms with low temps notnigh temps with fossil fuels)
- use of catalytic converters
how does using natural fixation processes instead of haber counteract N movements
using organic fertilisers, not storing waste near waterways (contamination)
methods to reduce nitrate leaching (counteracting N movements)
planting legume crops
apply fertilisers when not raining (less leaching)
use of low solubility fertilisers i.e. urea
‘buffer strips’ near waterways prevent leaching
Why do organisms need phosphorus?
DNA, RNA, Phospholipids, ATP, Bones
Name the 2 differences of the phosphorus cycle compared to N and C cycle
- no phosphorus in atmo.
- Phosphates not very soluble in H2O
(both make cycle slower compared to C/N cycles)
name the 3 impacts humans have on the P cycle
fertiliser use
mining of phosphate rocks
use of guano deposits
how does fertiliser use impact P cycle
- increase crop production
- leaching can cause eutrophication
- mobilises phosphorus in a more soluble form
how does mining of phosphate rocks impact P cycle
- phosphorus mined as calcium phosphate
- treated to become ammonium phosphate (more soluble)
- used to make fertiliser
how do the use of guano deposits impact P cycle
- plankton absorbs P
- fish eat plankton
- birds eat fish
- bird droppings rich in P (guano)
- humans collect guano organic fertiliser
Name the methods in which the P cycle can be sustainably managed
use of organic fertilisers choosing a crop with less need for P Crop rotation Crops which absorb P more efficiently Having suitable conditions for mycorrhizal fungi
name the method that is sustainable than the use of artificial fertiliser
using organic fertilisers
name the 2 methods that make use of the fact that crops need more of one mineral than the other
- choosing crop with less need for P
- crop rotation
name the 2 methods that increases phosphate uptake
- crops that absorb P more efficiently
- suitable conditions for mycorrhizal fungi
