Week 7 Flashcards
Key sources of dissolved iron (dFe) to the oceans:
-atmospheric deposition (Fe from mineral dust, combustion)
-marine sediments (Fe flux proportional to POM loading)
-hydrothermal vents (key source in deep ocean)
-riverine inputs (smaller source)
The flux of dust from the land to the atmosphere is a function of ____________, ______________, ____________, and _________________.
wind speed
soil moisture
soil texture
vegetation cover
Iron is deposited on the oceans from both __________ pattern and from _____________
combustion sources
mineral dust
____________________________ is a major source of the combustion aerosols
greenhouse gas combustion
Reducing greenhouse gas emissions, will ________ atmospheric Fe deposition to the oceans, potentially ____________ the biological pump and providing a positive feedback for global warming
reduce
weakening
Martin and colleagues suggested that the micronutrient iron was responsible for the observed _______________________ (______) conditions in the subarctic North Pacific, the equatorial Pacific, and in the Southern Ocean
High Nitrate, Low Chlorophyll (HNLC)
John Martin’s idea was ultimately proved correct by the open ocean ___________________
iron fertilization experiments
John Martin also proposed the “_____________” for _________________ cycles. Namely that higher dust/iron inputs to the oceans during ice ages, increased the efficiency of the biological pump, thus lowering atmospheric CO2 concentrations
Martin Hypothesis
glacial-interglacial
Where dissolved Fe concentrations exceed ligand concentrations, iron losses to particle scavenging _______________.
increase rapidly
Redfield N/P is 16
Deposition N/P > 1600
Excess ___ inputs
N
Diatoms N/Si is about 1, ranging from ~0.5 - 5.0
Deposition N/Si > 1000
Excess __ inputs
N
Phytoplankton N/Fe varies ~10,000 - 100,000
Deposition N/Fe < 1000
Excess ___ inputs
Fe
