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BIO220 > BIO220 Lecture 21 > Flashcards

BIO220 Lecture 21 Flashcards

Biochemical cycles

1
Q

Connection between nuclear weapons & ecological research

A

Cold War: Us vs. USSR

  • use nuclear weapons
  • radiation enter food chains -> affect crops, fish, livestock

Use radioactive tracers to see where chemicals go in natural communities

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2
Q

___ Project is the collaborative “big science” model that ecologists try to follow.

A

Manhattan

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3
Q

Manhattan Project

A

Group that produced atomic bombs

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4
Q

N cycle is a ___ cycle

A

gaseous

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5
Q

Human intervention in N cycle

A

N fertilizer, HB process, combustion of fuels

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6
Q

P cycle is a ___ cycle

A

sedimentary

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7
Q

human intervention in P cycle

A
  • mining
  • pollution
  • fishing
  • sewage & agriculture runoff
  • erosion
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8
Q

HYDROLOGIC CYCLE

A

water cycle

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9
Q

hydrologic cycle ____ and ___

A

pools & fluxes if time permits

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10
Q

human intervention in hydrologic cycle

A

freshwater diversion (used in agriculture)

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11
Q

cycle for large organic molecules

A

synthesized, consumed, broken down

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12
Q

cycle for chemical elements

A

not synthesized, but instead move around and change oxidation states/compartments

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13
Q

cycle comprises of…

A

pools & fluxes

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14
Q

____ can persist as much as elements, but experience phase changes

A

stable, long-lived compounds (water, pollutants, etc.)

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15
Q

C, N, P cycles are all tied to ___ cycle

A

hydrologic

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16
Q

C cycle is tied with…

A

trophic webs

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17
Q

what are the 2 elements most likely to limit plant productivity?

A

N, P

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18
Q

limiting steps of C cycle

A
  • creation by photosynthesis

- respiration/combustion of organic matter

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19
Q

human intervention in C cycle

A

combustion & extraction of fossil fuel, land conversion (deforestation)

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20
Q

why do humans deforest?

A
  • easier for hunting
  • land for agriculture
  • remove agricultural waste
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21
Q

C sequestered in trees is released by…

A

fire

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22
Q

transient effect of burning cut trees

A

add NPK to soil: short-term enrichment of soil

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23
Q

Evidence that Neolithic humans cleared forests

A

pollen in lake sediments

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24
Q

in the past, most of the pollen was found in ___. now, mostly found in ___. This is because…

A

woodland species;
open-country species;
woodland cleared to grasslands

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25
Q

People always deforested. Why is it a problem now?

A

we have the technology & labour power to do it faster.

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26
Q

What is 1 place where forests were restored?

A

Eastern North America (Rhode Island)

  • poor farm land
  • Sugar maples grew back
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27
Q

____ forests were cut for paper pulp in Maine, maritimes

A

coniferous

28
Q

current deforestation is mostly in the ___

A

tropics (South America)

29
Q

slash and burn

A

involves the cutting and burning of trees and plants in forests or woodlands to create fields
- release N & microelements

30
Q

reasons for clearing tropical forests

A
  • slash & burn

- lumber, pulp, plantation clearning

31
Q

oil palm plantation provides…

A

oil for food, biodiesel

32
Q

Tropical forests contain great stores of…

Example?

A

carbon (~1000 tons/hectare in Indonesian Kalimantan swamp forest, including both alive & dead plants)

33
Q

usually, tropical forests are too wet to burn, but ___ causes drying. Why?

A

Logging;

less cover, so sun & wind dry soil

34
Q

Peat

A
  • brown, soil-like material

- very smoky when burnt

35
Q

Tropical forests are reservoirs for __ diversity

A

species

36
Q

most recent example of tropical forest deforestation

A

Asian Fires (1997-1998): affected 5 million hectares

37
Q

Effect of logging on C

A
  • remove plants which can photosynthesize C out of atm

- dry out soil -> more easy to burn -> release stored C to atm

38
Q

Industrial revolution was powered by…

A

fossil fuel combustion

39
Q

Fossil fuel moves C from ___, burn it, and release…

A

stores (soil, bedrock, fossils);

CO2 & smoke into atm

40
Q

Cars are very efficient at…

A

fossil fuel -> atm CO2

41
Q

Human activities that release CO2 into atm

A
  1. Fossil fuel burning - 6 billion tons

2. Deforestation - 1.6 billion tons

42
Q

Is N soluble?

A

Yes

43
Q

There are ___ sedimentary pools for N

A

minimal

44
Q

Limiting step of N cycle

A

convert atm N2 -> nitrate or ammonium

45
Q

What usually converts atm N2?

A
  • Legume: Rhizobium
  • eubacteria
  • cyanobacteria
  • lightning
46
Q

N fixation

A

reduce N2 -> NH3

47
Q

Nitrification

A

NH4+ -> NO3- (nitrate)

48
Q

Denitrification

A

NO3- -> N2

49
Q

How do make N fertilizers?

A

fix N2 using electricity/natural gas

50
Q

N cycle is ___, meaning it cycles very fast

A

atmospheric

51
Q

Combustion of fuels releases which form of N into the atm?

A

NO2

52
Q

Humans are accelerating the N cycle so much that…

A

combustion exceeds natural production rates

- in some areas, rainwater is dilute fertilizer

53
Q

consequences of N found in rainwater

A
  • remove limiting nutrient for plants
  • reduce biodiversity
  • some plants favoured (weeds)
  • nitrate buildup in groundwater (hazard in agricultural areas)
  • eutrophication of costal waters -> anoxia
54
Q

P is mostly found in…

A

sedimentary pools (ocean sediments)

55
Q

Limiting step in P cycle

A
  • weathering of rocks in soil (mycorrhizae)

- geological uplift

56
Q

mycorrhizae helps…

A

plants take up phosphorus from soil (makes it soluble)

57
Q

P has no __ forms

A

gaseous

58
Q

___ is sometimes an important input of P

A

atm dust from Saharan Africa

59
Q

Phosphate

A

PO4^-3

60
Q

is phosphate soluble?

A

technically yes, but bound by soil components

61
Q

P is a ___ cycle, so it is slow

A

sedimentary

62
Q

sources of P for humans

A
  • mining

- guano

63
Q

P is lost from terrestrial systems by…

A
  • run-off
  • erosion
  • over-application of fertilizers
  • eutrophication of rivers & lakes

Ends up back in marine sediments

64
Q

Biggest P reserves

A

Morocco > USA > South Africa

65
Q

Liquid peruvian guano has higher ___% than bat guano

A

P

66
Q

What areas are best sources of guano? Why?

A

islands off the coast of Peru

  • lots of seabirds, no predators
  • fish best in areas with cold-water upwelling
  • which brings P up to surface
  • bird eat P-rich fish
  • dry climate: P is not washed by rain back to ocean

BIO220 (24 decks)

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