Ocean Chemistry

Chemical Properties

Physical Properties

Foundations

Aristotle Robert Boyle Edmund Halley Count Luigi

Ferdinando Marsigli Antoine Laurent

Lavosier Joseph Louis Gay-

Lussac Alexander Marcet

Johann Georg Forchhammer

William Dittmar Justus von Liebig James Johnstone Vladimir Ivanovich

Vernadsky Alfred Redfield

Forms of Matter

The Water Molecule

The Water Molecule

The Water Molecule

Dissolving Ability

Universal solvent Polar nature & hydrogen bonding

Conservative ions Major constituents have very constant ratios

to one another Not generally removed or added by living

organisms

Nonconservative ions Change concentrations depending on

season, locale and biological processes

Dissolved Gases

The most abundant gases in the atmosphere and in the oceans: Nitrogen (N2) Oxygen (O2) Carbon dioxide (CO2)

Dissolved Gases Saturation concentration

The maximum amount of any gas that can be held in solution

Temp, salinity & pressure Solubility has an inverse relationship with

temp and salinity Solubility has a direct relationship with

pressure

Distribution with Depth Photosynthesis

Sunlight + H2O + CO2 C6H12O6 + O2

Respiration Organics + O2 CO2 + H2O + Energy

Decomposition Uses up oxygen

O2

Hypoxic Anoxic Anaerobic

O2 and CO2

CO2

45 – 54 mL/L

Oxygen minimum zone

Sources of Salt Continental weathering

Riverine input Volcanic gases

Source (& Sink) of Salt Hydrothermal vents

Discovered in 1977 Geyser on the seafloor Spews super-hot, mineral-rich water Very biodiverse

Source (& Sink) of Salts Hydrothermal vents

Black Smokers Hottest of the vents Spew iron and sulfide,

which combine to form iron monosulfide (FeS)

White Smokers Cooler temp Barium, Calcium and

Silicon

Regulating the Salt Balance - Sources & Sinks

Residence Time RT =Amount of

ionRate of

input or removal

CO2 and The World Ocean

The pH of Seawater H+

Hydrogen cation OH-

Hydroxide anion

H+ = OH- H+ < OH- H+ > OH-

Neutral Alkaline Acidic

Buffering Capacity of CO2

Buffer Substance that prevents sudden, or large,

changes in acidity or alkalinity of a solution

CO2 + H2O H2CO3 H+ + HCO3- 2H+ + CO3

2-

Fig. 6.18

Fig. 6.19

Fig. 6.20

Fig. 6.21

Page 103