Why is the ocean salty?

Rainfall and Rainfall Types Frontal Orographic Convective

In each case, water evaporates, moves into the atmosphere, cools and condenses. The water that condenses as rainfall is freshwater How does the ocean become salty?

What is a salt?

Ions

Elements Electrons (-) Protons (+) Elements in the periodic table have equal numbers of protons and electrons. They are electrically neutral

Ions Ions are stable forms of elements that acquire an electrical charge by gaining or losing electrons Elemental Sodium (Na) 11 protons (+), 11 electrons (-) Sodium ion (Na + ) 11 protons (+), 10 electrons (-) By losing an electron, sodium has more protons than electrons and becomes positively charged. Na - 1e - = Na +

Ions Ions are stable forms of elements that acquire an electrical charge by gaining or losing electrons Elemental Chlorine (Cl) 17 protons (+), 17 electrons (-) Chloride ion (Cl - ) 17 protons (+), 18 electrons (-) By gaining an electron, chlorine has more electrons than protons and becomes negatively charged. Cl + 1e - = Cl -

Elements that lose electrons and become positively charged are called cations. Na +, K +, Ca 2+, Mg 2+, Cu 2+, Fe 3+ Elements that gain electrons and become negatively charged are called anions. Cl -, Br -, F -, I - CO 3 2-, SO 4 2-, PO 4 -3 oxoanions

Salts KCl, NaCl, MgCl 2, CaCO 3, CaSO 4 Cations: K +, Na +, Mg 2+, Ca 2+ Anions: Cl -, CO 3 -2, SO 4 -2 Salts are formed by combining cations and anions to form solids that have no charge. K + + Cl - = KCl Na + + Cl - = NaCl

Conversely, if solid salts are mixed with water they dissolve and the ions go into solution KClK + + Cl - NaClNa + + Cl - Water solid solution

KCl NaCl CaCO 3 CaSO 4 K + and Cl - Na + and Cl - Ca +2 and CO 3 -2 Ca +2 and SO 4 -2 Solid Dissolved Solution ions Dissolution

Oceans have enormous amounts of salt dissolved in the water. Where does it come from?

10%

Overland Flow (Runoff) Evaporation / Transpiration Aquifers/ Groundwater Infiltration to Soil/Soil flow Fate of Precipitation to Land Streams, Rivers, Lakes

Watershed River basin Drainage basin Catchment Total land area that drains surface water to a common point. Rain that falls anywhere within a given body of water's watershed or basin will eventually drain into that body of water.

Atlantic

salts Watersheds, Erosion and Dissolution salts Dissolution of salts; erosion of rocks and minerals rain

Dissolved in water water Minerals and Erosion KAlSi 3 O 8 CaAl 2 Si 2 O 8 NaAlSi 3 O 8 K +, Ca 2+, Na +, Si 4+ Feldspars KAlSi 3 O 8 CaAl 2 Si 2 O 8 NaAlSi 3 O 8

Dissolved Salts and Minerals KCl NaCl MgCl 2 CaCO 3 CaSO 4 KCl NaCl MgCl 2 CaCO 3 CaSO 4 KAlSi 3 O 8 CaAl 2 Si 2 O 8 NaAlSi 3 O 8 KAlSi 3 O 8 CaAl 2 Si 2 O 8 NaAlSi 3 O 8 Rivers contain small amounts of dissolved salts that are delivered to the oceans

Total Salts Rivers < 500 mg/L Oceans35,000 mg/L (3.5% salt) Evaporating 1 cubic foot of sea water yields about 2 pounds of salt

Rivers < 500 mg/L Oceans35,000 mg/L If rivers have low salt contents, why do oceans have such high salt contents? Evaporation

Salts left behind evaporation

condensation

Salts are delivered to the oceans in small amounts Evaporation removes water from the oceans, but leaves the salts behind. Rainfall on land dissolves more salts, which are subsequently delivered to the oceans

Microcosm: The Dead Sea 35% salt content Elevation: 1400 ft below sea level Endorheic sea

Great Salt Lake 5 to 27% Salt Content Railroad causeway Remnant of Lake Bonneville one inch to six feet thick Jordan Weber Bear

The Aral Sea (up to 8% salinity) Amu Darya and Syr Darya rivers 60% loss in area 80% loss in volume

Oceans

What kind of Salts?

KCl NaCl MgCl 2 CaCO 3 CaSO 4 KCl NaCl MgCl 2 CaCO 3 CaSO 4 River Water Ion Carbonate Calcium Sulfate Silicate Chloride Sodium Magnesium Potassium River Salt Composition Dominated by Carbonate, Calcium, Sulfate, and Silicate KAlSi 3 O 8 CaAl 2 Si 2 O 8 NaAlSi 3 O 8 KAlSi 3 O 8 CaAl 2 Si 2 O 8 NaAlSi 3 O 8

Ocean Salt Composition Ion Chloride Sodium Sulfate Magnesium Calcium Potassium Carbonate Silicate Sea Water (%) Dominated by Chloride, Sodium, Sulfate, and Magnesium 2.9% Na + and Cl - (85% of total)

River Water Sea Water Ion Carbonate Calcium Silicate Sulfate Chloride Sodium Magnesium Potassium Percentage of Total Dissolved Minerals } 79% } 85%

Enrich Sodium, Chloride in ocean water Remove Silica, Calcium, Carbonate from river water Alterations

sodium, potassium, and ammonium salts are soluble chloride, bromide and iodide salts are soluble. NaCl Solubility 350 g/L Solubility: ease of dissolution in water Enriching Sodium and Chloride Once these types of ions reach the oceans they stay dissolved

Calcium Carbonate Removal Incorporate into shells of marine invertebrates Remove Silica, Calcium, Carbonate Ca 2+ + CO 3 2- = CaCO 3

Diatoms Life and Silica Remove Silica, Calcium, Carbonate Use silica as structural material

River Water Sea Water Ion Carbonate Calcium Silicate Chloride Sodium Magnesium Potassium Sulfate Percentage of Total Dissolved Minerals

Next: Freshwater