Lecture 16 Respiration

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Lecture 16 Respiration
Aerobic Respiration Apparent Oxygen Utilization
(AOU) Regenerated and Preformed Nutrients Revised
RKR Ratios
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The Ocean Conveyor
What is it conveying? (at the surface? and at
depth?)
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Summary of vertical circulation
What is happening above the thermocline boundary?
Fill in appropriate arrows.
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Sinking and Remineralization
Remineralization keeps the biological pump
pumping!
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Aerobic respiration Oxygen is consumed and
nutrients are released. (CH2O)106(NH3)16(H3PO4)
138 O2 Algal Protoplasm
? bacteria 106 CO2 16 HNO3
H3PO4 122 H2O trace elements The
oxidation of the NH3 in organic matter to NO3
is referred to as nitrification
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Apparent Oxygen Utilization (AOU) Apparent
Oxygen Utilization or AOU. AOU is defined
as AOU O2' - O2 where O2' value of O2
the water would have if it was in equilibrium
with the atmosphere at the temperature and
salinity of the water. This is called
saturation. This implies that all waters are in
equilibrium with the atmosphere (100 saturated)
when they sink to become the deep ocean water.
O2 is the dissolved oxygen actually measured in
the same water sample.
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AOU at 4000m
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Winter Outcrops of Isopycnal Surfaces
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Surface density, isopycnal outcrops
Waters will move mostly along surfaces of
constant density.
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Density Sections
3H penetration depth during GEOSECS
Atlantic
Indian
Pacific
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so 27.0
so 27.5
AOU Section Western Atlantic
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s 27.0
s 27.5
AOU Section Western Pacific
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Nutrients versus AOU
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Oxidative and Preformed Nutrients versus Depth
1 mol O2 106/138 mol CO2 16/138 mol
HNO3 1/138 mol H3PO4 consumed 0.77 CO2
0.12 HNO3 0.0072
H3PO4
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DP PO4 - PO4? RPO4/O2 x AOU DN NO3
- NO3? RNO3/O2 x AOU
on s? 27.0 to 27.2
Takahashi et al, 1985
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Remineralization Ratios versus Depth
average for 400m to 4000m P N C
O2 1 161 11714 17010
Anderson and Sarmiento, 1994)
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It is clear that more O2 (170 moles) is
actually required to respire sinking organic
matter than was originally calculated from the
RKR equation (138 moles). The RKR type organic
matter has an oxidation state as for carbohydrate
(CH2O). Real plankton have 65 protein, 19
lipid and 16 carbohydrate (from NMR
studies) The higher O2 demand suggests that
sinking organic matter has more of a lipid-like
nature. Instead of CH2O O2 CO2
H2O More like CH2 3/2 O2 CO2 H2O
Real plankton biomass is more like
C106H177O37N17S0.4 instead of
C106H260O106N16 Complete oxidation requires 154
moles of O2 instead of 138
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(No Transcript)
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NO, NO3 and O2 versus Salinity
NO 9 NO3 O2
In Western South Atlantic From AAIW to NADW