Gasses and Climate Flashcards
(31 cards)
What is solubility of gas dependent on?
Temperature and alinity
Higher temperature = (salts)…
More solubility- increased energy means solute particles aren’t as tightly bound and solvent molecules can more easily dissolve them
Higher temperature = (gases)…
DECREASES solubility. Gas molecules gain kinetic energy making them more likely to escape from the liquid and return to gas phase
Sources of gases in the ocean
–> Ocean-gas exchange through diffusion- CO2, O2, N2
–> Biological activity (photosynthesis, decomposition)
–> Underwater vents (release H2S, CH4, CO2)
Sinks of gases in the ocean
–> Air-Sea exchange (CO2 and O2 released- e.g. abundant phytoplankton)
–> Sedimentation - can trap organic matter and CO2
–> Chemical reactions e.g. coccolithophores CaCO3
Wave and current turbulence - regulating concentration of gases in water
Increases the exchange of seawater gases with the atmosphere
Difference in gas concentration- regulating concentration of gases in water
Gases diffuse across the air-sea interface from high to low areas of concentration until chemical equilibrium is attained
Salinity - regulating concentration of gases in water
A rise in salinity decreases the solubility of gases
Pressure - regulating concentration of gases in water
Increased pressure increase solubility of gases
pH - regulating concentration of gases in water
Controls the relative concentrations of various species of CO2 in water (HCO3-)
Oxygen minimum zone (OMZ)
Naturally hypoxic water. O2 < 0.45ml/L, 20umol/L
Biological Pump
Phytoplankton etc. take up O2 for photosynthesis and when they die they take O2 with them and bacteria consume O2
Strong thermal stratification
Warmer water forms a distinct layer on top of cold water reducing vertical mixing in the ocean and limits gas exchange with atmosphere
Predication for O2 levels in the ocean
Global warming= increased ocean temp= decreased O2 solubility
= warmer waters= stratification increased= reduced mixing
CO2 gas dissolves in water to form
CO2 (aq) - henry’s law
What happens to CO2(aq) once in water?
CO2 (aq) + H2O <–> H2CO3
H2CO3 <–> HCO3- + H+
HCO3- <–> CO32- + H+
Total CO2 =>
CO2 (aq) + HCO3- + CO32-
Bicarbonate buffer:
Sea water too basic –>
H2CO3–> HCO3- + H+ (pH drops)
Bicarbonate buffer :
Sea water too acidic –>
HCO3- + H+ –> H2CO3 (pH rises)
Alkalinity
The ability of a solution to neutralise addition of acid
Addition of CO2 from respiration/ other methods
Increases DIC and lowers pH
Dissolution of CaCO3
will add CO32- and INCREASE ALKALINITY and DIC
Higher pH (less H-)
Changes the speciation away from CO2 and therefore concentration of CO2 will decrease
Formation of CaCO3
Lowers alkalinity and lowers pH
