Ocean Properties and Chemistry

Ocean Properties

Physical Properties of Water

• Importance of water: We are made of 70% of water and some ocean organisms are made up to 90% water

• Polar• Excellent solvent• Hydrogen bonds

(makes water sticky= cohesion, keeps water stable at different temps.

• Specific heat (ability to hold onto heat)

• Ability of light to penetrate water

Ability of light to penetrate water

150 meters

150 meters

900 meters

900 meters

1000 meters or more

1000 meters or more

Chemical Properties of Water

• Acidity and alkalinity• pH scale– 0-7 acidic– 7 neutral– 7-14 alkaline

• Seawater is slightly alkaline between 8.0-8.6 on average– Acid:_amount of hydrogen ions H+– Base:_amount of hydroxide ions OH-

More Chemistry

Importance of pH in the oceans• When carbon dioxide (CO2) is absorbed by

seawater, chemical reactions occur that reduce seawater pH, and saturation states of biologically important calcium carbonate minerals

No calcium Carbonate, No shells

• Projected sea water in 2100 will dissolve the shells of all sea life

Gases in Seawater

• Gases from biological processes– Photosynthesis________– Cellular respiration______– Decomposition________

• Oxygen-minimum zone• Solubility of gases in seawater• Environmental variables affect amount

of gases:__________

Oxygen Levels In the ocean 700 m -1200 m OMZ

Composition of Seawater• Ionic salts– Sodium (Na+)– Magnesium (Mg2+)– Calcium (Ca2+)– Potassium (K+)– Chloride (Cl-)– Sulfate (SO4

2-)

• Trace elements

Salinity

Salinity: How much salt is dissolved in water, it is measured in ppt (parts per thousand) oceans are around 30 ppt

• 3.5% salt and 96.5% water by mass

Salinity• Salinity changes due to:• evaporation: high salinity • precipitation and runoff: low salinity

Salinity in Bays and Estuaries• Less than 25 ppt is called brackish, meaning a

combination of salt water and fresh water. • Bays and Estuaries have Brackish water

Tides (Changes Salinity)• Low Tide: Low

salinity• High Tide: Normal

Salinity• (Bays Estuaries)

Physical Properties of Water1. List 5 physical properties of ocean water2. What is Salinity? Where does it change in the

oceans?3. How does the oxygen content change in the

ocean?4. What is the difference between an acid and a

base?5. Describe how light travels in water.6. Give an example of a polar molecule and how it

dissolves other polar substances.