Earth’s Oceans
◦70-71% of Earth’s crust covered by ocean water
◦4 Major OceansPacific – largest and deepestAtlantic- little larger than the Indian
Indian – same depth as Atlantic, but smaller
Arctic – smallest and shallowest
World’s Oceans
How is the ocean the largest source of fresh water?
Water Cycle
◦Ocean water: a mixture of dissolved gases and solids in pure water
◦ Contains 85 of 90 naturally existing elements
◦96.5% pure water; 3.5% dissolved minerals
Properties of Ocean Water
◦Salinity – amount of dissolved salts in ocean waterexpressed in ppt (parts per thousand)
# of grams of salts dissolved in 1 kg of ocean water
Properties of Ocean Water
◦Sources of minerals - (NaCl the most common)Volcanic activityErosion from land (upstream)Waves breaking on the land
Properties of Ocean Water
Precipitation, runoff, and melting sea ice and icebergs - result in lower salinity
Formation of sea-ice and evaporation – result in higher salinity
Salinity is usually the same; differences result from
N, CO2, and O Amount varies with depth – cold water holds more gases
Oxygen/ CO2 cycle between plants and animals same as on land
Most abundant gases in ocean water