ECOL 3505H Lecture Notes - Lecture 22: Ocean Acidification, Biological Pump, Denitrification
19 Oct 2016
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CO2 water chemistry drives C flux
Compare CO2 in the oceans and the atmosphere
Oceans and the air → equilibrium CO2
CO2 + H2O <-> H2CO3 <-> H+ + HCO3- <-> 2H+ + CO32-
Bicarbonate is the major form of carbon in the oceans
More CO2 in the air → less available calcium
(Ocean acidification)
Oeans hae een a sink for anthropogeni CO2, or here CO2 an settle in.
Oceans absorb a lot of energy without increasing in temperature and can absorb a lot of CO2 as well
Global C cycles depends on biotically and abiotically driven fluxes
Different components of the C cycle operate on very different timescales
Humans are quickly increasing CO2 in the atmosphere – rapid response tied to residence time
C uptake in the ocean is driven biotically and abiotically
What else limits the rate of this biological pump?
Nitrogen is also critical for life and has a cycle driven by life
N required for proteins and other structural molecules
Most N is in the atmosphere but N2 is directly unusable by life
16 ATP required to break the N-N triple bond
Unlike for photosynthesis, light cannot be used to N → what can be used as an energy source?
N, also critical for life, has a more complicated cycle driven by life than C
Like C, N is transformed under aerobic and anaerobic conditions
-But there are more pathways making the whole cycle more complex
-Oxygen is not the only electro acceptor in this cycle
Figure 23.11 part 2
Nitrogen excretion – if organisms have excess N, they dump it (NH3)
Decomposition → N release from amino acids (amine → NH3 → NH4+)
→production of NH3 and NH4+ (reduced forms)
NH3 can be oxidized to nitrate (NO3) to generate energy
Nitrogen uptake – almost always as inorganic species (NO3 and NH4)
Nitrate (NO3) can be used to generate energy as well, but when??
NO3 → NO2 → NO → N2O → N2
-This is known as denitrification
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Document Summary
Compare co2 in the oceans and the atmosphere. Co2 + h2o h2co3 h+ + hco3- 2h+ + co32- Bicarbonate is the major form of carbon in the oceans. More co2 in the air less available calcium (ocean acidification) O(cid:272)eans ha(cid:448)e (cid:271)een a (cid:862)sink(cid:863) for anthropogeni(cid:272) co2, or (cid:449)here co2 (cid:272)an settle in. Oceans absorb a lot of energy without increasing in temperature and can absorb a lot of co2 as well. Global c cycles depends on biotically and abiotically driven fluxes. Different components of the c cycle operate on very different timescales. Humans are quickly increasing co2 in the atmosphere rapid response tied to residence time. C uptake in the ocean is driven biotically and abiotically. Nitrogen is also critical for life and has a cycle driven by life. N required for proteins and other structural molecules. Most n is in the atmosphere but n2 is directly unusable by life.
