Seawater Chapter 15 Section 2

Chemical Properties Seawater = 96.5% water and 3.5 % salts Salinity is the measure of the amount of dissolved salts in seawater; expressed in ppt (parts per thousand) 3.5% = 35ppt Nutrients and dissolved gases in seawater greatly affect sea life Salinities can vary from place to place

Sources of Sea Salt Volcanic gases – sulfate and chloride ions Weathering Na and Ca come from feldspars Fe and Mg Flushed into rivers and transported to oceans Salts are removed from the ocean at the same rate they are added

Physical Properties Higher density than freshwater Ranges from 1.02 g/mL to 1.03 g/mL Density varies according to salinity Cold water is denser than warm water Freezing point of seawater is lower than freshwater (-2 degrees Celsius) Oceans are dark because water absorbs light

Ocean Layering Average surface temp. = 15 degrees Celsius Temperature profile Figure 15-15 (397) Three layers Figure 15-16 (397) Surface layer - warm Thermocline - transitional Bottom layer - cold

Water Masses Three water masses in the deep water of the Atlantic Ocean. Antarctic Bottom Water North Atlantic Deep Water Antarctic Intermediate Water Indian and Pacific contain only two water masses