Biogeochemical cycles Flashcards

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1
Q

What is bio-geochemistry?

A

study of how living organisms, geological
processes, and chemical interactions drive the cycling of elements in
the Earth’s systems.

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2
Q

What is the comparison of % N, O and CH4 on earth, venus and mars?

A

N: E= 78 V= 3.5 M= 2.7
O: E= 21 V=trace M=0.13
CH4: E=0.002 V= 0 M= 0

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3
Q

What is a cycle?

A

a series of changes that comes back to the starting point and can be repeated

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4
Q

What is the difference between an open and closed system?

A

open= parts can be lost
closed= nothing added or lost

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5
Q

What can we assume when there is a slow rate of change in a system?

A

steady state- equilibrium

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6
Q

How have humans changed the carbon and nitrogen cycle?

A

burning fossil fuels
fertiliser application

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7
Q

What is a flux?

A

the movement of matter or energy from one reservoir to another

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8
Q

What evidence is there that earth hasn’t always been in equilibrium?

A

banded iron formation that only occurred up until 1.8 billion years ago with alternating layers showing high and low oxygen conditions

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9
Q

What was CO2 ppm like when there was a lack of biological life?

A

6000

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10
Q

How does the keeling curve show seasonality?

A

The peaks and troughs on the graph (ignoring general increasing trend) are due to the seasons reducing photosynthetic and thus carbon uptake in NH

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11
Q

What is carbon sequestration?

A

the removal of carbon from the atmosphere and storage

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12
Q

What is the distribution of carbon between the biosphere, atmosphere and hydrosphere?

A

50% atmo
25% both bio and hydro

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13
Q

What is BIFoR face facility?

A

decadal experiment to study the response of a mature temperate deciduous forest ecosystem to elevated CO2

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14
Q

What is the infrastructure at BIFoR?

A

3 no-infrastructure controls (ambient air);
3 ambient-air FACE rings &
3 treatments of +150 ppmv CO2

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15
Q

Will increasing CO2 increase carbon storage?

A

More CO2 will enter bio by photosynthesis but in autumn trees which have made more leave will all fall to ground decay and release CO2 back into atmo

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16
Q

How is the best way that plants can lead to increased CO2 storage?

A

If when photosynthesising more due to increased CO2 levels they transfer it to the soil where it will stay for longer

17
Q

What factors need to be considered when asking if trees can keep pace with CO2 emissions?

A

Maturity
Climate
Nutrient availability
Water availability
Species
Soil type
Sunlight

18
Q

How long does anthropogenic CO2 stay in the atmo?

A

around 200 years to enter the ocean

19
Q

What is the majority of nitrogen in the terrestrial ecosystem like?

A

biologically unavailable (geo and atmo)

20
Q

How much of N is available?

A

1%

21
Q

What is the difference between reactive and non-reactive nitrogen?

A

Reactive (Nr) = inorganic reduced N (ammonia) and inorganic oxidised forms (NOx) and organic compounds (Urea)

22
Q

What have humans done to reactive nitrogen availability?

A

roughly doubled

23
Q

What are the key processes in the nitrogen cycle?

A

Fixation
Mineralisation
Immobilisation
Plant uptake
Nitrification
Denitrification

24
Q

What happens with nitrogen fixation?

A

input N2 to NH3

25
Q

What happens with nitrogen mineralisation?

A

breakdown organic matter to NH3

26
Q

What happens with nitrogen Immobalisation?

A

microbial uptake

27
Q

What happens with nitrification?

A

Conversion NH3 to NO3-

28
Q

What happens with denitrification?

A

NO3- to N2

29
Q

What are riparian buffers?

A

Riparian- adjacent/ on bank of water body or stream
Buffer- reduction impact of surrounding land use

30
Q

Where are riparian buffers commonly used?

A

agricultural areas
Diffuse pollution

31
Q

What will happen to redox over a landscape?

A

Will high O2 area that will transition to a hypoxic area found near water body
Mottled zone in the middle (dominated by drying and flooding)

32
Q

What is the land like above the redox boundary?

A

oxic with occasional flooding and O2 ingress

33
Q

What will happen in the soil as you approach the redox boundary?

A

reduction in oxygen so more limiting for microorganisms as soil becomes hypoxic

34
Q

What will the hypoxia zone be like?

A

Some respiration
Denitrification
Nitrification slowdown

35
Q

What conditions can facultative anaerobes be in?

A

more diverse conditions can use O or other sources but prefer O as more efficient

36
Q

What conditions can oligate anaerobes survive in?

A

Need anoxic (no oxygen)

37
Q

What is the unit for redox potential?

A

mV- millivolts

38
Q

What are the general redox potentials for varying oxidised and reduced soils?

A

Well oxidised soils= +700 - +500
Moderately reduced soils= +400 - +200
Reduced soils= +100 to -100
Highly reduced soils= -100 to -300

39
Q
A