Binder notes Flashcards
AOU equation
AOU = [O2]sat - [O2]obs
Equation to calculate changes in nitrate and phosphate from AOU
P = Po + (AOU/138) N = No + 16*(AOU/138)
If there is no calcium carbonate production or dissolution, does carbonate alkalinity change?
No.
What elements can be limiting in the ocean?
Fe, N, P, Si
What microbe mediated respiratory process yields almost as much energy as aerobic respiration?
Denitrification
Why is aerobic respiration the favored OM oxidation pathway when O2 is available?
It has the greatest energy yield.
Which ratio(s) are more variable C:P, N:P, or C:N
C:P and N:P
What are two tracers can be used to date younger water masses?
CFCs and C-14
What is the effect of denitrification on the Redfield ratio?
Denitrification strips nitrate from the water column, which decreases the N:P ratio.
Why are preformed nutrient concentrations characteristic of HNLC regions?
Some areas are nutrient limited. Regions like Sub Arctic Pacific, Equatorial Pacific, and Antarctic ocean are iron limited. Thus, not all of the nutrients are used up by primary productivity.
What are preformed nutrients?
Nutrients that were present in a water mass before downwelling.
Preformed nutrients = total nutrients - regenerated nutrients
What does a positive AOU value mean?
O2 used up through aerobic respiration. O2(sat) is greater than O2(obs).
Why does an increase in AOU relate to an increase in nitrate, phosphate, and carbon dioxide?
Because nitrate, phosphate, and carbon dioxide are the inorganic products of OM degradation.
What do microbes use as an e- acceptor during aerobic respiration?
Oxygen
What is the oxidation number of an element in its free uncombined state (or combined with itself)?
Zero.
What does the oxidation state represent?
The total number of electrons which have been removed from an element (a positive oxidation state) or added to an element (a negative oxidation state) to get to its present state.
What is the oxidation state of a monoatomic or polyatomic ion?
The charge of the ion.
Which N form contains nitrogen at its highest oxidation state? What is N’s oxidation number in that form?
Nitrate. +5
Which N form contains nitrogen at its lowest oxidation state? What is N’s oxidation number in that from?
Ammonium, -3
Simple forward/backward reaction for photosynthesis/respiration
CH2O + O2 CO2 + H2O
pH (water): meaning and formula
potential hydrogen ions from the disassociation of water
Negative log of hydrogen ion activity
pH = -log(aH+)
Reaction of CO2 + H2O
H2CO3
Four parameters that define carbonate speciation
TCO2, pCO2, TA, and pH
Why is pH considered the master variable?
Because it drives the relative distribution of carbonic acid, carbonate, and bicarbonate.
Why is pH=7 considered neutral?
Because the concentration of hydrogen ions equals the concentration of hydroxide ions produced from the disassociation of pure water at standard temperature and pressure.
Why is CO2, by definition, an acid?
Because when dissolved in water it produces hydrogen ions.
What happens, in terms of the carbonate equilibrium equations, when the pH of SW is lowered?
The addition of hydrogen ions push the equilibrium expressions to the towards the left, which favors CO2* and consumes carbonate and excess H+.
Effective partial pressure of CO2 in SW
The partial pressure that the gas would have in the overlying atmosphere if an equilibrium is reached with the concentration of [CO2*]
What is the dominant form of dissolved inorganic phosphorus in salt water?
HPO4(2-) phosphoric acid
What drives DIP speciation?
pH
Equation for TCO2 if OM remineralization is equal to CaCO3 dissolution
TCO2 = TCO2o + 2(106AOU)/138
Equation for TCO2 if all OM remineralization and no CaCO3 production or dissolution?
TCO2 = TCO2o + 106*(AOU/138)
If CaCO3 production or dissolution is of equal importance to OM remineralization, then what is the ratio of ALK to TCO2?
How would I get an ALK value from TCO2?
1:1
ALK = TCO2
What sets the regeneration ratio of inorganic species in the open ocean?
Elemental ratio of sinking OM
What makes nitrogen gas stable, but difficult to incorporate by organisms?
Triple bond
What is the redox cascade of electron acceptors in sediments?
Oxygen, nitrate, Manganese(IV), Iron(III), sulfate, carbon (methanogenesis)
What are four likely marine N cycle controls?
1) factors promoting denitrification/anammox 2) suboxic conditions (poor ventilation/high respiration) 3) availability of nitrate 4) availability of OC
How might low O2 in Peru lead to a deviation from the Redfield ratio?
Low O2 leads to low nitrate, but doesn’t affect phosphate
What does the AOU of a water sample represent?
The sum of the biological activity that the sample has experienced since it was last in equilibrium with the atmosphere.
Where have iron experiments occurred?
Galapagos, Southern Ocean, sub arctic.
Primary productivity
photosynthetic formation of organic matter
gross primary production
the amount of carbon fixed (CO2 converted into organic matter) by photosynthetic organisms (per unit time per unit volume)
Net primary production
the total carbon fixed minus the amount respired by the primary producer.
