Announcements in class 2/5/07

• Movie Wed. Don’t miss it! Material will be on the exam. Only one showing.

• Problem Set 4 is posted online. Print it out yourself. PS 4 is due in class Monday, 2/12/07

• PS 5 will be posted Mon. 2/12 and due Wed. 2/21

Outline

• f-ratio

• Phosphorous Cycling

• Carbon Cycling

NitratePhytoplankton

Up

wel

lin

gM

ixin

g

Vertical

Flux

N2 FixationRiversDeposition

PONDIN

Euphotic Zone

f-ratio

Upwelling Zone 0.8Gyre 0.1Global Average < 0.5

New Production

New + Regenerated Production

Sediment traps

to catch

sinking particles

Sustainable yields

NitratePhytoplankton

Up

wel

lin

gM

ixin

g

Ver

tica

lF

lux

N2 FixationRiversDeposition

PONDIN

Euphotic Zone

Fishing

New Production

Oligotrophic gyres

Upwelling regions

↑Annual ↓Perennialr-selected K-selected

Chemical Forms – P

• PO43- (Phosphate)

• Organic

The cycling of Phosphorus

Dissolved Inorganic Particulate Organic

uptake

excretion

Runoff

upwelling sinkingdecomposition

Balance maintained via weathering of rock

Chemical Transformations – P

• AssimilationPO4

3- → OrganicPhytoplankton or other autotrophs

• RemineralizationOrganic → PO4

3-

Heterotrophs

• ExcretionOrganic → DissolvedHeterotrophs and Autotrophs

Experimental Lakes Area

Lake 227

Lake 226C, N, PEutrophic algal blooms

C, N

Lake 227

Oligotrophic Lake Eutrophic Lake

25 - 100 micrograms/liter phosphorus > 15 micrograms/liter phosphorus

Chemical forms of Carbon• Inorganic

– CO2

– bicarbonate ion HCO3-

– carbonate ion CO32-

• Organic (fixed …)

• Dissolved (DIC and DOC)

• Particulate (biomass and detritus)

Carbonate Equilibrium

• CO2 «» HCO3- «» CO3

2-

dissolved bicarbonate carbonate

CO2 ↑ HCO3- ↑ CO3

2- ↑ pH ↓

Ocean pH 8.2

Source NASA

Source R. Rohde

C Cycle “Food Web” Diagram

P

Z

BDissolvedInorganicCarbon

DissolvedOrganicCarbon

Main Thermocline

CO2

DissolvedInorganicCarbon

DissolvedOrganicCarbonDeep Remineralization

Sinking Particles

PteropodForaminiferaCoccolithophore

Carbon

• Solubility Pump– Solubility of CO2 is greater in cooler water

– Deep water formation ↑DIC– C pumped from atmosphere to ocean

• Biological Pump– POC and PIC sinking, DOC downwelling– C pumped from surface ocean to depth

Deep Water Formation

Source: USC

Thermohaline circulation

Saharan Dust Storm Over the Atlantic

The Cycling of Silicon

Dissolved Inorganic Particulate Organic

uptake

Runoff

upwelling sinkingdissolution

Balance maintained via weathering of rock