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Origins of Ocean Salts
10%
90% of rainfall is on the oceans
Watershed
River basinDrainage basinCatchment
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.
AmazonWatershed
Atlantic
saltssalts
Watersheds, Erosion and Dissolution
saltssalts
Dissolution of salts; erosion of rocks and minerals
rain rain
Dissolved in water
water
water
water
Minerals and Erosion
KAlSi3O8
CaAl2Si2O8
NaAlSi3O8
K+, Ca2+, Na+, Si4+
Feldspars KAlSi3O8
CaAl2Si2O8
NaAlSi3O8
granite
Dissolved Salts and Minerals
KCl
NaCl
MgCl2
CaCO3
CaSO4
KCl
NaCl
MgCl2
CaCO3
CaSO4
KAlSi3O8
CaAl2Si2O8
NaAlSi3O8
KAlSi3O8
CaAl2Si2O8
NaAlSi3O8
Rivers contain small amounts of dissolved salts that are delivered to the oceans
AmazonWatershed
Atlantic
K
Na
Mg
Cl
Ca
CO3
Ca
SO4
Si
K
Na
Mg
Cl
Ca
CO3
Ca
SO4
Si
Rivers < 500 mg/L
Oceans 35,000 mg/L
If rivers have low salt contents and theyare delivering salts to the oceans, why dooceans have such high salt contents?
Total Salts
Salts left behind
evaporation
The primary factor leading to ocean salinity.
Salts are delivered to the oceans in small amounts
Evaporation removes water from theoceans, but leaves the salts behind.
Rainfall on land dissolves more salts, whichare subsequently delivered to the oceans
What kind of Salts?
KCl
NaCl
MgCl2
CaCO3
CaSO4
KCl
NaCl
MgCl2
CaCO3
CaSO4
River Water35.1520.3912.14 11.675.685.793.412.12
IonCarbonateCalciumSulfate SilicateChlorideSodium
MagnesiumPotassium
River Salt Composition
Dominated by Carbonate, Calcium, Sulfate, and Silicate
KAlSi3O8
CaAl2Si2O8
NaAlSi3O8
KAlSi3O8
CaAl2Si2O8
NaAlSi3O8
Ocean Salt Composition
IonChlorideSodiumSulfate
Magnesium Calcium
Potassium Carbonate
Silicate
Sea Water (%)55.0430.627.683.69 1.151.100.40
.0004
Dominated by Chloride and Sodium
Na+ and Cl-(85% of total)
Cl- Na+
River Water35.1520.3911.6712.14 5.685.793.412.12
Sea Water.40
1.15.00047.68
55.0430.623.691.10
IonCarbonateCalciumSilicateSulfate ChlorideSodium
MagnesiumPotassium
Percentage of Total Dissolved Minerals
}79%
}85%
• Enrich Chloride and Sodium 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 salt dissolution in water
Enriching Sodium and Chloride
Once these types of ions reach the oceans they stay dissolved
IonChlorideSodiumSulfate
Magnesium Calcium
Potassium Carbonate
Silicate
Sea Water (%)55.0430.627.683.69 1.151.100.40
.0004
Both chloride salts and sodium salts areextremely soluble in water and do not
combine with other elements to form solids
• Enrich Chloride and Sodium in ocean water
Remove Silica, Calcium, Carbonate from river water
Alterations
SodiumChloride
Sulfate
Ca+2
Cl-
Na+
CO3-2
SO4-2
solid
Carbonate
Calcium
Precipitation and Carbonate Removal
Calcium and carbonate are at near saturation levels in oceans(amounts are close to a threshold for precipitation)
Ca2+ + CO32- = CaCO3
Corals
Mollusks
CaCO3
MgCO3
Marine Calcium and Magnesium Carbonate
Carbonate Deposition/Sedimentation
Foraminifera
Algae
Diatoms
Life and Silica
• Remove Silica, Calcium, Carbonate
Use silica as structural material
River Water35.1520.3911.675.685.793.412.12
12.14
Sea Water.40
1.15.000455.0430.623.691.107.68
IonCarbonateCalciumSilicateChlorideSodium
MagnesiumPotassium
Sulfate
Percentage of Total Dissolved Minerals
Next: Saltwater to Freshwater
