1. Physical Oceanography Salinity

2. Salt has always been a valuable commodity to mankind. Its antiseptic and preservative powers have long been known. Salt has always been used as currency and the word ‘salary’ is derived from the word ‘salt.’ Even today, many tropical societies use salt as currency.

3. Seawater Average seawater is composed of three things: water (96.5%), salt (3.5%) and trace amounts of cosmic dust. The most abundant ions in salt are chlorine (Cl - ) and sodium (Na + ), which together make up about 86% of all salts in the ocean.

4. What is Salinity? Salinity = total mass (grams) of dissolved material in 1 kg of seawater Average salinity = 35g salt/kg of seawater = 35 parts per 1000 = 35‰, or 3.5% This is equivalent to 2.5 teaspoons of salt in 1 L of water

5. Examples of Salinity Bottom of Dead Sea270 ‰ Great Salt Lake, Utah280 ‰ Red Sea37-46 ‰ Persian Gulf35-40 ‰ Sargasso Sea (world’s saltiest open ocean water) 38 ‰ Black Sea18 ‰ Baltic Sea (numerous rivers run into it) < 10 ‰

8. Terminology Hypersaline Water: salinity > 47 ‰ Brine: salinity from 36-47 ‰ Brackish Water: salinity < 17 ‰ (mixture of fresh and salty, mostly in bays, inlets and river mouths)

9. Are the following hypersaline, brine, brackish, normal, or a combination? Bottom of Dead Sea270 ‰ Great Salt Lake, Utah280 ‰ Red Sea37-46 ‰ Persian Gulf35-40 ‰ Sargasso Sea38 ‰ Black Sea18 ‰ Baltic Sea< 10 ‰

10. Bottom of Dead SeaHypersaline270 ‰ Great Salt Lake, UtahHypersaline280 ‰ Red SeaBrine37-46 ‰ Persian GulfBrine/normal35-40 ‰ Sargasso SeaBrine38 ‰ Black SeaBrackish/ normal 18 ‰ Baltic SeaBrackish< 10 ‰

11. How is Ocean Salinity Measured 1.How well it conducts electricity A salinometer: a water sample is placed in it – you get a digital readout of the salinity Greater Conductivity = Higher Salinity

13. 2. Measure the refraction of light A refractor is used to measure the amount of ‘bending’ that occurs when light passes through water. Greater Refraction = Higher Salinity

15. 3.CTD Sensor Lowered over the side of a ship, it measures conductivity, temperature and pressure/density all at once.