Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MONITORING COASTAL AND ESTUARINE SYSTEMS > Coastal carbon cycle > Flashcards

Coastal carbon cycle Flashcards

1
Q

What are the forms of carbon in the ocean?

A
  • Dissolved inorganic carbon (DIC)
  • Dissolved organic carbon (DOC)
  • Particulate organic carbon (POC)
  • Total organic carbon (TOC) = DIC + POC
  • Particulate inorganic carbon (PIC)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the allochthonous inputs of carbon to estuaries?

A
  • rivers
  • seawater
  • submarine groundwater discharge
  • bordering wetlands (mangroves and fresh/salt water marshes

come from somewhere, not in situ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the autochthonous inputs?

A
  • plankton
  • emergent & submergent aquatic vegetation in estuary (e.g. seagrasses)
  • secondary production (zookplankton, fish, benthic animals)

produced in situ, within the coastal ocean

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Explain the riverine inputs of carbon to the ocean.

A
  • close to 1Gt of carbon discharged via rivers annually; around 40% DIC
  • fluxes are primarily regulated by discharge; DOC is affected by temp too
  • hydrologic events have a disproportionate effect; tropical storms can be responsible for more than 40% of the average annual riverine DOC export, and single large flood events can export 80-90% of POC from mountainous regions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Explain the terrestrial DOC sources to the ocean.

A
  • derived from terrestrial vegetation and soils
  • historically considered recalcitrant, hence conservative in estuaries
  • largely composed of aromatic carbon (lignin inputs from vascular plant material)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Explain the terrestrial POC sources to the ocean.

A
  • plant biomass
  • physical erosion of catchment rocks; in estuaries, coagulation occurs due to increasing abundance of cations
  • phases most easily leached out are low MW carbohydrates, proteins and fatty acids
  • most refractory phases are cellulose and lignin
  • black carbon; oxidation products of fossil fuel and biomass combustion. occurs in fine particulate and colloidal form. direct aerosol deposition in rivers and estuaries
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What sort of carbon signficant source to coastal waters is submarine groundwater discharge?

A

DOC

20-30% of river flux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What latitudes to salt marshes and mangroves occur at and what is their significance to productivity?

A

salt marshes = mid to high latitude
mangroves = low latitude

among the most productive ecosystems on earth 400-2250g C m-2 yr-2
they produce and lock up a lot of carbon

some of this carbon is exported to estuaries

but these habitats are experiencing a steep decline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the transformations of C in estuaries?

A
  • mineral sorption & desorption & photochemical dissolution can lead to INTERCHANGE between DOC and POC
  • loss of org carbon by microbial degradation and photochemical oxidation, scavenging, sedimentation & salinity-induced flocculation of DOC & POC
  • outgassing of CO2 derived from OC respiration & DIC inputs from rivers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

DOC may behave conservatively or non-conservatively during estuarine mixing. When is there conservative behaviour?

A
  • if riverine DOC is non-reactive
  • if estuarine residence time is short compared to the DOC reactivity
  • estuarine sources of DOC are small
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the additional inputs of DOC?

A
  • mangroves, saltmarshes etc

- resuspension events

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the removal processes of DOC?

A

flocculation (e.g. HMW humics)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Explain CO2 exchange in estuaries

A
  • estuarine waters are signif sources of CO2 to the atmosphere (around 0.25Pg C yr-1)
  • estuaries are HETEROTROPHIC; they respire more org C than they produce, and there is a DIC/CO2 excess
  • only 10-50% of riverine DOC is respired in estuaries, and most POC deposited offshore, so CO2 loss is likely largely supported by MICROBIAL DECOMPOSITION of org C produced in coastal wetlands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the fate & transformation of C on continental shelves?

A
  • continental shelves occupy 7-10% of global ocean area, but contribute 10-30% of global prim production, 30-50% of inorganic carbon & around 80% of organic C burial in sediments, which could contribute up to ~50% of OC supplied to deep ocean.

see the diagram in notes
- transformations include microbial degradation and flocculation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Explain the CO2 exchange in shelf waters.

A
  • estuaries and inner shelf waters close to land tend to be CO2 sources, due to high resp rates of terrestrial & estuarine organic C, and lateral transport of high CO2 waters from inshore systems
  • whereas mid to outer shelf waters are CO2 sinks, due to decreased terrestrial organic C supply, increased prim production as light conditions improve offshore, and increased nutrient accessibility from upwelling and mixing across the shelf break
  • the CO2 sink in the coastal ocean is around 0.36Pg C yr-1; 21% of global ocean net air-sea CO2 flux
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Between which latitudes are sources/sinks of CO2?

A
  • shelves located betw 30 and 90* latitude tend to be CO2 sinks
  • shelves betw equator and 30° lat tend to be sources of CO2
17
Q

What is the difference between the trophic state of continental shelves of pre-industrial times vs today?

A

pre-industrial times = continental shelves were probably heterotrophic

today, shelves are a CO2 sink, so autotrophic

18
Q

What are the possibilities of why today’s shelves are CO2 sinks?

A
  • result of enhanced biological uptake of CO2 due to stimulation of shelf prim production by increased anthropogenic inputs from land
  • or, increased physical uptake of atmospheric CO2 as atmos CO2 levels have increased more than those of shelf waters
19
Q

What trophic state are estuaries in? What does this contrast with?

A

Heterotrophic; they’re CO2 sources to the atmosphere.

this contrasts with shelves, which are autotrophic as they’re CO2 sinks.

20
Q

How much does the COASTAL OCEAN SINK constitute the global ocean sea-air flux?

A

around 21%

21
Q

What is the principle allochthonous source of carbon to the coastal ocean?

A

Rivers. around 55% is in inorganic carbon form, and 45% in organic carbon.

MONITORING COASTAL AND ESTUARINE SYSTEMS (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions