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Environmental science > Biogeochemical cycles > Flashcards

Biogeochemical cycles Flashcards

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Biology 101 flashcards
1
Q

definition of biogeochemical cycle

A

interlined processes involving living organisms that all materials to be recycled and repeatedly reused (prevents build up of waste)

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2
Q

Name the 3 human actions that affect photosynthesis in the carbon cycle + explain

A

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.

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3
Q

Name the 3 biogeochemical cycles

A

carbon
nitrogen
phosphorus

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4
Q

Name the human action that affects changes to aerobic respiration in the carbon cycle

A

soil disturbance/ploughing = increase aeration, increase aerobic respiration for organisms, more DOM

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5
Q

Drainage of marshes and destruction of peat bogs lead to…

A

more CH4 being released into atmo. CH4 oxidised to become CO2

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6
Q

Name 3 human actions that increase CH4 release

A

Cattle farming, padi fields, anaerobic respiration in landfill

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7
Q

Name 3 knock on effects of climate change on the carbon cycle

A

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

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8
Q

Ocean acidification is due to…

A

carbonic acid being created by CO2 being dissolved in the ocean from any human activity that releases CO2 . More H+ ions = more acidic

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9
Q

name 5 ways to sustainably manage carbon cycle

A
  • alternative to fossil fuels
  • conservation of biomass
  • carbon sequestration and CCS
  • matching afforestation to deforestation
  • increasing soil organic matter (main carbon sink of soil)
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10
Q

Name the 2 different pre-combustion tech (CCS)

A
  1. gasification = converts fuel into CO2+H. CO2 removed. H used as fuel
  2. Oxy-fuel combustion systems = combustion of fuel in pure O, only H2O vapour and CO2 produced (easier to separate)
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11
Q

Post-combustion tech (CCS)

A

removing CO2 from exhausts through 3 different methods

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12
Q

Name the 3 methods of Post-combustion tech (CCS)

A
  1. high pressure CH4 filtration
  2. Dissolving CO2 in solvent
  3. Cryogenic (low temp) separation
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13
Q

Name the 2 different ways carbon can be stored (CCS)

A
  1. normally stored underground i.e. depleted aquifers

2. or used to aid oil recovery (secondary oil recovery)

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14
Q

In the Carbon cycle name 2 processes that are aerobic

A

plants and animals respiring aerobically. Phytoplankton respiring aerobically

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15
Q

for the carbon cycle: crop removal _______ the amount of DOM

A

decreases

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16
Q

name at least 2 of the 4 reasons why organisms need nitrogen

A

to synthesise:

ATP, DNA, Proteins, Chlorophyll

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17
Q

what is nitrogen fixation + what carries it out

A
  • taking atmospheric N into the soil
  • Produces ammonia
    + done by nitrogen fixing bacteria
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18
Q

what is ammonification + what carries it out

A
  • decomposition of DOM
  • produces ammonia
    + done by decomposers
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19
Q

what is nitrification + what carries it out

A
  • converting ammonia into nitrite then into nitrate
  • nitrate absorbed by plants
    + done by nitrifying bacteria
20
Q

what is denitrification + what carries it out

A
  • reducing nitrate into N and NOx gases
  • N released back into atmo.
    + done by denitrifying bacteria
21
Q

what is leaching

A
  • nitrates leach (soluble so wash out of soil)
  • leads to loss of nutrients
  • can act as nutrients for aquatic organisms in water bodies
22
Q

Name the 7 ways humans impact the nitrogen cycle

A 
haber process 
growing legumes 
water logging 
sewage disposal 
combustion processes 
drainage/ploughing 
leaving crop residue after harvest
23
Q

what is the haber process? and how does it impact the N cycle

A
  • 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
24
Q

How does growing legumes impact N cycle

A
  • legumes have nitrifying bacteria in their root nodules (increase fixation)
    + increase nitrates in soil
25
Q

How does drainage/ploughing impact N cycle

A
  • 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.)
26
Q

how does sewage disposal impact N cycle

A
  • 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
27
Q

how does combustion processes impact N cycle

A 
- 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
28
Q

how does leaving crop residue impact N cycle

A

addition of nitrates to soil

29
Q

how does waterlogging impact the N cycle

A

example: growing rice in padi fields
- increase anaerobic conditions
+ increase denitrification = decrease nitrates in soil

30
Q

Name all of the aerobic processes in the N cycle

A

fixation
ammonification
Nitrification

31
Q

Name all the anaerobic processes in the N cycle

A

denitrification

32
Q

name the 4 methods f counteracting anthropogenic N movements

A

reduced combustion processes
use of natural fixation processes (instead of haber)
management of biological waste
methods to reduce soil nitrate leaching

33
Q

how does reduced combustion processes counteract N movements

A
  • 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
34
Q

how does using natural fixation processes instead of haber counteract N movements

A

using organic fertilisers, not storing waste near waterways (contamination)

35
Q

methods to reduce nitrate leaching (counteracting N movements)

A

planting legume crops
apply fertilisers when not raining (less leaching)
use of low solubility fertilisers i.e. urea
‘buffer strips’ near waterways prevent leaching

36
Q

Why do organisms need phosphorus?

A

DNA, RNA, Phospholipids, ATP, Bones

37
Q

Name the 2 differences of the phosphorus cycle compared to N and C cycle

A
  • no phosphorus in atmo.
  • Phosphates not very soluble in H2O
    (both make cycle slower compared to C/N cycles)
38
Q

name the 3 impacts humans have on the P cycle

A

fertiliser use
mining of phosphate rocks
use of guano deposits

39
Q

how does fertiliser use impact P cycle

A
  • increase crop production
  • leaching can cause eutrophication
  • mobilises phosphorus in a more soluble form
40
Q

how does mining of phosphate rocks impact P cycle

A
  • phosphorus mined as calcium phosphate
  • treated to become ammonium phosphate (more soluble)
  • used to make fertiliser
41
Q

how do the use of guano deposits impact P cycle

A
  1. plankton absorbs P
  2. fish eat plankton
  3. birds eat fish
  4. bird droppings rich in P (guano)
  5. humans collect guano organic fertiliser
42
Q

Name the methods in which the P cycle can be sustainably managed

A 
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
43
Q

name the method that is sustainable than the use of artificial fertiliser

A

using organic fertilisers

44
Q

name the 2 methods that make use of the fact that crops need more of one mineral than the other

A
  • choosing crop with less need for P

- crop rotation

45
Q

name the 2 methods that increases phosphate uptake

A
  • crops that absorb P more efficiently

- suitable conditions for mycorrhizal fungi

Environmental science (19 decks)

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