A summary of the lectures of Marine Sciences 3, Utrecht University (2020) given by Appy Sluijs and colleagues.
Contains images from the lectures which increases the number of pages.
Carbon in the Ocean
Pre-industrial pCO2~ 280 ppmv
2020 pCO2~ 413 ppmv
~ 1/3 of anthroprogenic C in ocean)
(ppmv=ppm by volume)
Carbonation: increase in DIC by CO2 dissolving in the ocean en dan krijg je
deze reactie
Acidification: increase of hyrodrogen ions
Increase in carbonation, results in increase of acidification
,Slide 30: largest uncertainty how much CO2 we are going to emit, graph a
gedeelte tussen rood en blauw is de uncertainity
Slide 32: surface veel primaire productie
Onder bepaalde zone, alleen respiratie nog dus
CO2 accumuleert
Slide 33:
Solubility pump: changes in solubility due to temperature decrease with
increasing depth; responsible for 1/3 of the gradient
Biological pump: responsible for 2/3 of the gradient
• Organic carbon pump: fixation of CO2 by photosynthesis, net flux of
CO2 from atmosphere to ocean
• Carbonate counter pump: calcification takes place which produces CO2
resulting in export of CO2 from ocean to atmosphere
→ transport of CO2 between atmosphere and ocean surface layer happens
through Henry’s law
Henry’s law: a gas law that states that the amount of dissolved gas in a liquid is
proportional to its partial pressure above the liquid, meaning that a higher
concentration in one medium results in transport of the gas to the other medium
,The Marine Organic Matter Cycle
GPP: gross primary production, total rate of carbon fixation/oxygen release by
phytoplankton
NPP: Net primary production, as GPP is partly used for respiration (Ra) by
phytoplankton
Ra: respiration of phytoplankton
Rh: consumption of organic matter by heterotrophs for growth and respiration
NEP: the remaining organic matter which is available for export
-NPP most relevant for euphotic zone food web functioning
-NEP most relevant for biological pump and benthic food webs
Slide 38: ezelsbrug: stel de getallen voor als geld (getallen van linker afbl 50 t
0.2)
, E-ratio= Export Production / Net Primary
Production
• Temperature determines the degree to
which NPP organic matter is exported,
• Magnitude of NPP is also important;
higher NPP → higher e-ratio
→ Higher temperature results in lower E-
ratio meaning less biomass reaches the sea
floor so less food availability for benthic
life
Biological response to pH
Processes:
• Calcification: needs carbonate (CO3 2-)
• Primary production: needs CO2 or HCO3-
• Nitrogen fixation, Nitrification
• And more…
Ocean acidification, Biology and Earth System
• OA stimulates primary production and export → CO2 sink
• OA limits calcite production → less CO2 production
→ results in ocean being a stronger CO2 sink and becomes more acid
Ocean CO2 uptake in future
• Oceans take up about 25-30% now
• Increase because of CO2 stimulated growth of phytoplankton and/or less
calcification (biology)
• Decrease because of decline in buffer capacity (chemistry)
• Decrease because of warming and stratification (phyics)
→ long-term fate of anthropogenic carbon depends on physics, chemistry
and biology
Slide 58: despite many uncertainties a long-term drop of nutrients in the open
ocean and NPP is expected
Part 2
IPCC: Intergovernmental Panel on Climate Change
Slide 71: clouds cause uncertainties
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