Ocean chemistry and physics

Salt wedge estuary

freshwater flows in over the denser saltwater

well-mixed estuary

tidal and wind forces water to mix top to bottom

partially-mixed estuary

interaction btw. these forces in combination with shape of basin creates intermediate types

fjord estuary

fjords result from glacial action that creates deep channels and shallow sills near the mouth

reverse estuary

inverted estuaries occur when evaporation concentrates salt in dry river bed-inland water saltier than ocean

seawater

1. pH>8

2. high ionic content

3. low nutrients

4. low organic matter

5. high sulfate

freshwater

1. pH 4-8

2. low ionic content

3. high nutrients

4. high organic matter

5. low sulfate

role of estuaries in biogeochem

estuaries trap particles and org. matter, release phosphate that was previously trapped on particles, convert nitrogen to N2 and DON (in wetlands), decrease ratio of inorganic N:P in dissolved phase

Where do cations and anions in the ocean come from

1. weathering of crustal rock

2. substances released by volcanoes

what do calcium carbonate precipitates do

remove Ca

What does the carbonate buffer system do

can fix the resulting charge imbalance quickly

What is most of the inorganic carbon in the ocean

bicarbonate (HCO3) at pH of ocean

What must be removed from seawater to balance the loss of calcium due to calcification?

2 bicarbonates

What does calcification result in regarding atmospheric and dissolved CO2?

Disequilibrium

What is the effect of calcification on the amount of inorganic carbon in ocean water?

Ocean water holds less inorganic carbon

How is pH affected by calcification?

It is complicated

What is in dynamic equilibrium in addition to CO2

dissolved and atmospheric CO2

what is the balance between species determined by

pH of ocean

Consequences to CO2 addition

1. increasing CO2 in atmosphere results in increasing dissolved CO2 in the ocean

2. disequilibrium of the carbonate buffer system results

3. at pH of ocean usually means conversion of H2CO3 to HCO3 which slows increase in H (decrease pH) and decreases CO3 and increases HCO3

declining atmospheric CO2

1.results in ocean pH increases as dissolved CO2 is lost to atmosphere

2. carbonate ion increases in response to increasing pH

3. calcium carbonate deposition increases

4. pH goes down again

increasing atmospheric CO2

1. CO2 invades and converts to bicarbonate, releasing protons

2. ocean pH decreases

3. carbonate ion decreases in response to decreasing pH

4. calcium carbonate dissolution occurs

5. pH goes up again

hydrothermal vents

usually located at spreading zones btw. tectonic plates

role of hydrothermal vents in ocean chemistry

1. deoxygenation

2. precipitation

3. weathering at high temps

4. precipitation

net effects of hydrothermal vents

K and SO4 removed, trace metals introduced (CU, Fe, Zn)

What are surface currents arranged into in oceans

gyres

ekman transport

effect of winds on currents modified by coriolis effect

what does the ekman transport do

determines current direction at top and bottom of gyres

1. easterly trade winds force equatorial currents west

2. westerlies force north atlantic current east

3. water piles up in southwest and northeast atlantic

seasonal winds and coastal upwelling

1. summer makes ocean cool relative to land

2. warm air over land rises-leads to low pressure

3. air from land and hadley cell sink over ocean-leads to high pressure

4. air descends and spreads outward from high pressure areas, coriolis causes CYCLONIC circulation

which direction do south and northwinds go

south-east coast

north-west coast

upwelling

if winds along coast force water offshore, surface water must get replaced by colder deep water

downwelling

if winds along coast force water onshore, surface water is forced deeper

hurricanes

1. need warm water

2. need coriolis effect

3. only start poleward of 10N and 10S and over warm water

4. follow prevailing winds