Salinity

What is the difference between a fish and a piano? You can't tuna fish.

Objectives Students will be able to discuss the sources of, and variations in, the oceans salinity.

Salinity The amount of dissolved salts in ocean water Average of 3.5% Indicator solutions can be used to determine if salt is present (AgNO3) Salinity can be measured quantitatively with a hydrometer.

Salinity Variations

Salinity Variations Average salinity of ocean is 34.7 Parts per thousand (‰) Salinity varies with latitude: At 20° North latitude, and 20° South latitude the salinity is 36‰ Less precipitation, more evaporation. Slightly more salty than the equator

Variation Continued Fresh water from rivers or streams and rainwater runoff lowers salinity

Depth and Salinity Salinity varies with depth Salinity at the bottom is greater than the surface Halocline - layer of water between 100 and 200m which displays a rapid change in salinity Colder water down deep causes salt ions to move closer together, increasing salinity

Where does the salt come from? Sodium Chloride (NaCl) Salts erode from stream and river beds and flow towards ocean Hot water thermal vents on the ocean floor spew hot water containing dissolved minerals, including sodium and chloride

Questions How does the salinity of ocean water vary with depth? How does the salinity of the ocean vary with latitude? Describe some sources of the salt found in the sea.