1. 15 – 2 Sea water

2. Chemical Properties of Sea Water Sea water is 96.5% water, 3.5% salts Sea water is 96.5% water, 3.5% salts Salinity: Salinity: –Measures the amount of dissolved salts in sea water –Expressed in ppt (parts per thousand) –35 ppt = 3.5% –Most abundant salt in the ocean is sodium chloride (NaCl) –Others include magnesium sulfate (MgSO 4 ) and Calcium Chloride (CaCl 2 )

3. Salinity Variations Actual salinities vary from place to place Actual salinities vary from place to place Regions of high evaporation have greater salinity Regions of high evaporation have greater salinity –37-38 ppt Regions of low evaporation have lower salinity Regions of low evaporation have lower salinity –32-33 ppt

4. Salinity Sources Salinity not much different then years ago Salinity not much different then years ago Evaporation leaves salt behind Evaporation leaves salt behind Calcium shells of marine organisms dissolve Calcium shells of marine organisms dissolve Weathering of rocks produces salinity Weathering of rocks produces salinity

5. Removal of Salts Small salty spray droplets from breaking waves are picked up by wind and deposited on land Small salty spray droplets from breaking waves are picked up by wind and deposited on land Marine organisms remove the ions to make their shells Marine organisms remove the ions to make their shells

6. Physical Properties of Sea Water Denser than fresh water Denser than fresh water –Salt ions heavier than water molecules Freezing point is lower Freezing point is lower –Salt lowers Freezing point (about -2 o C)

7. Physical Properties Water Absorbs light: Water Absorbs light: –Water is clear but gets dark going down Which color travels furthest? Which color travels furthest? –Light only penetrates water in first 100 m down Photosynthesis only good at top Photosynthesis only good at top

8. Ocean Layering Surface Temps. -2 o C – 30 o C Surface Temps. -2 o C – 30 o C Layers due to density difference Layers due to density difference Temps decrease with depths Temps decrease with depths –Surface (0-100 m ) relatively warm –Thermocline: rapid decrease in Temp. –Bottom Cold Temps near freezing (4 o C)