Ocean Composition Salinity Salinity a measure of the

Ocean Composition

Salinity • Salinity – a measure of the amount of dissolved solids in a given amount of liquid –Measured as grams of dissolved solids per kilogram of water • 1 kg of ocean water contains 35 g of dissolved solids

Where does all that salt come from? • Precipitation – Acid rain breaks down rocks dissolved salts and minerals are carried away (runoff) rain and dissolved salts and minerals are deposited in the ocean

• Hydrothermal Vents – Result of seawater filtering down in the ocean crust where it meets the magma – Minerals in the crust begin to dissolve, adding to the salt content of the ocean • Underwater Volcanoes – Similar to the process with hydrothermal vents, during an underwater eruption, seawater reacts with hot rock and some minerals are dissolved into the ocean water

What affects salinity? • Climate –Coastal water in places with hotter, drier climates has a higher salinity –Coastal water in cooler, more humid places has a lower salinity 1. More fresh water from streams and rivers run into the ocean in these areas 2. Glaciers melting add freshwater to the oceans –Heat INCREASES the evaporation rate. Evaporation removes water but leaves salts and other dissolved solids behind.

• Water Movement – Slower moving areas of water develop higher salinity • Example: bays, gulfs, seas, open ocean without currents moving running through them Dead Sea = Very Salty – 337 PPT (33. 7%) Baltic Sea = Not Very Salty – 10 PPT (1%)

Salinity, Density, and Temperature • Salt makes seawater more dense than freshwater • Oceans with a higher salinity are going to have a higher density • Warmer water = lower density • Colder water = higher density *Water that is cold and high in salt will sink to the bottom of the ocean floor due to its density*