Gasses and Climate

Question 1

What is solubility of gas dependent on?

Answer 1

Temperature and alinity

Question 2

Higher temperature = (salts)…

Answer 2

More solubility- increased energy means solute particles aren’t as tightly bound and solvent molecules can more easily dissolve them

Question 3

Higher temperature = (gases)…

Answer 3

DECREASES solubility. Gas molecules gain kinetic energy making them more likely to escape from the liquid and return to gas phase

Question 4

Sources of gases in the ocean

Answer 4

–> Ocean-gas exchange through diffusion- CO2, O2, N2
–> Biological activity (photosynthesis, decomposition)
–> Underwater vents (release H2S, CH4, CO2)

Question 5

Sinks of gases in the ocean

Answer 5

–> Air-Sea exchange (CO2 and O2 released- e.g. abundant phytoplankton)
–> Sedimentation - can trap organic matter and CO2
–> Chemical reactions e.g. coccolithophores CaCO3

Question 6

Wave and current turbulence - regulating concentration of gases in water

Answer 6

Increases the exchange of seawater gases with the atmosphere

Question 7

Difference in gas concentration- regulating concentration of gases in water

Answer 7

Gases diffuse across the air-sea interface from high to low areas of concentration until chemical equilibrium is attained

Question 8

Salinity - regulating concentration of gases in water

Answer 8

A rise in salinity decreases the solubility of gases

Question 9

Pressure - regulating concentration of gases in water

Answer 9

Increased pressure increase solubility of gases

Question 10

pH - regulating concentration of gases in water

Answer 10

Controls the relative concentrations of various species of CO2 in water (HCO3-)

Question 11

Oxygen minimum zone (OMZ)

Answer 11

Naturally hypoxic water. O2 < 0.45ml/L, 20umol/L

Question 12

Biological Pump

Answer 12

Phytoplankton etc. take up O2 for photosynthesis and when they die they take O2 with them and bacteria consume O2

Question 13

Strong thermal stratification

Answer 13

Warmer water forms a distinct layer on top of cold water reducing vertical mixing in the ocean and limits gas exchange with atmosphere

Question 14

Predication for O2 levels in the ocean

Answer 14

Global warming= increased ocean temp= decreased O2 solubility
= warmer waters= stratification increased= reduced mixing

Question 15

CO2 gas dissolves in water to form

Answer 15

CO2 (aq) - henry’s law

Question 16

What happens to CO2(aq) once in water?

Answer 16

CO2 (aq) + H2O <–> H2CO3
H2CO3 <–> HCO3- + H+
HCO3- <–> CO32- + H+

Question 17

Total CO2 =>

Answer 17

CO2 (aq) + HCO3- + CO32-

Question 18

Bicarbonate buffer:
Sea water too basic –>

Answer 18

H2CO3–> HCO3- + H+ (pH drops)

Question 19

Bicarbonate buffer :
Sea water too acidic –>

Answer 19

HCO3- + H+ –> H2CO3 (pH rises)

Question 20

Alkalinity

Answer 20

The ability of a solution to neutralise addition of acid

Question 21

Addition of CO2 from respiration/ other methods

Answer 21

Increases DIC and lowers pH

Question 22

Dissolution of CaCO3

Answer 22

will add CO32- and INCREASE ALKALINITY and DIC

Question 23

Higher pH (less H-)

Answer 23

Changes the speciation away from CO2 and therefore concentration of CO2 will decrease

Question 24

Formation of CaCO3

Answer 24

Lowers alkalinity and lowers pH

Question 25

POC

Answer 25

Particulate Organic Carbon

Question 26

PIC

Answer 26

Particulate Inorganic Carbon

Question 27

Downward flux of carbon

Answer 27

PIC sinks faster than POC and is less susceptible to remineralisation

Question 28

Higher PIC : POC ratio

Answer 28

Indicates a more efficient carbon pump in terms on pCO2 reduction

Question 29

Factors determining the proportioning of C between atmosphere and the ocean

Answer 29

• Temperature
• Efficiency of the biological pump
• Ventilation of deep ocean

Question 30

PETM

Answer 30

Paleocene-Eocene Thermal Maximum (PETM)

Question 31

What happened at the PETM?

Answer 31

A massive influx of C into the ocean-atmosphere, lowering the pH of the ocean