Ocean Water
Why is the ocean salty?Why is the ocean salty?
What is a salt?
Salts are made from Ions
Elements
Electrons (-)
Protons (+)
Elements in the periodictable have equal numbersof protons (+) and electrons (-).
They are electrically neutral
Ions
Ions are stable forms of elements that acquirean 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 thanelectrons and becomes positively charged.
Na - 1e- = Na+
Na11 protons
e-
e-
e-
e-
e-
e-
e- e-
e- e- e-
+
Na+
Sodium Na
2Na + 2H20 2Na+ + 2 OH- + H2
http://video.google.com/videoplay?docid=-2158222101210607510&ei=syO5SuaVBJLiqgKWif37AQ&q=sodium+explosion&hl=en#
Ions
Ions are stable forms of elements that acquirean 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 thanprotons and becomes negatively charged.
Cl + 1e- = Cl-
Cl17 protons
e-
e-
e-
e-
e-
e-
e- e-
e- e-
e-
e-
e-
e-
e- e-
e-e- _
Cl-
Chlorine
Elements that lose electrons and becomepositively charged are called cations.
Na+, K+, Ca2+, Mg2+, Cu2+, Fe3+
Elements that gain electrons and becomenegatively charged are called anions.
Cl-, Br-, F-, I-
CO32-, SO4
2-, PO4-3
oxoanions
Salts
KCl, NaCl, MgCl2, CaCO3, CaSO4
Cations: K+, Na+, Mg2+, Ca2+
Anions: Cl-, CO3-2, SO4
-2
Salts are formed by combining cations andanions 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
KCl K+ + Cl-
NaCl Na+ + Cl-Water
Water
solid solution
CaCO3
CaSO4
Ca+2 and CO3-2
Ca+2 and SO4-2
NaCl
Cl-
Na+
Na ClCl
ClCl
Dissolution
Oceans have enormous amountsof salt (ions) dissolved in the water.
Where does it come from?
10%
90% of rainfall is on the oceans
Overland Flow (Runoff)
Evaporation / Transpiration
Aquifers/ Groundwater
Infiltration to Soil/Soil flow
Fate of Precipitation to Land
Streams, Rivers, LakesStreams, Rivers, Lakes
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 ErosionMinerals 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 SaltsTotal 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
Microcosm: The Dead Sea
34% salt content
Elevation: 1400 ft below sea level
Endorheic sea
Lowest dry elevation on earth
59 inches of Evaporation/yr
10% of naturalflow now reaches the sea.
Sea levels are dropping by 3 ft/yr
Salt Works
1973
1987
2000
The Dead Sea is Dying
Great Salt Lake
5 to 27% Salt Content5 to 27% Salt Content
Railroad causeway
Remnant of Lake Bonneville (15,000 years ago)
one inch to six feet thick
JordanWeberBear
The Aral Sea (up to 8% salinity)
Amu Darya and Syr Darya rivers
60% loss in area80% loss in volume
Oceans and Rivers
4 billion tons of dissolved salts to the ocean annually
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, Sodium, and Sulfate
2.9% Na+ and Cl-
(85% of total)
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%
Carbonate, calcium and silicate are disappearingChloride and sodium are appearing
River Water has high amounts ofCalcium, Carbonate, and Silicate
Ocean Water has high amounts ofSodium and Chloride
If ocean salts come from rivers, some processis removing calcium, carbonate, and silicates from the river water, and sodium and chlorideare being enriched in ocean waters.
• 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
Ca2+ + CO32- = CaCO3
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
Other Constituents in Ocean Water
The Oceans and Carbon Dioxide
Chemical interaction between the Oceans and the Atmosphere
Gases Dissolve in Water
GasGases
dissolution
Composition of the Atmosphere
Gases
Nitrogen 78.1%Oxygen 20.9%Argon 0.93%CO2 0.038%
Oxygen
Solubility: 0.043 g/L(20oC)
Carbon Dioxide
C
O
O-
-
+
Carbon Dioxide
Middle Ages
IndustrialRevolution
ocean removed about 118 billion metric tons.
Between 1800 and 1994, the
48 percent of all fossil fuel emissions
380 ppm
Solubility = 1.69 g/L
CO2
(Oxygen Solubility: 0.043 g/L)
GasGases/Heat
Present and Future Problems
Solubility = 1.69 g/LOxygen Solubility: 0.043 g/L
Carbon Dioxide also is an Acid
CO2
WaterAcid
CO2 + H2O H2CO3
H2CO3 H+ + HCO3-
H+ is acid
Acids (H+) are reactive and dissolve a number of substances
Dissolution of Carbon Dioxide
Copper and Silver Cleaning:
CuO + 2HCl → CuCl2 + H2O
Ag2O + 2 HCl → 2 AgCl + H2O
CaCO3 + H+ Ca2+ + HCO3-
Fe2O3 + 6H+ 2Fe3+ + 3H2OFe2O3
CaCO3
Invertebrate shells and skeletons largely CaCO3
Corals, “lithic” plankton, clams, oysters
http://www.npr.org/templates/story/story.php?storyId=17243164
CaCO3 + H+ Ca2+ + HCO3-
CO2
WaterH+
Acidification of the oceans Inhibits the calcification and
growth of invertebrates
Analysis of coral cores shows a steady drop in calcification over the last 20 years
pH change: 8.179 to 8.104
Coral Reef Bleaching
Corals live in very nutrient poor waters and have certain zones of tolerance to water temperature, salinity, UV radiation, opacity, and nutrient quantities.
Anthropogenic Inputs
Homework II Oceanic Dead ZonesThis is an excerpt from a news story from June 21 by the AP concerning recent
Mid-west flooding and its potential impact on the dead zone in the Gulf of Mexico.
Flood, size of gulf dead zone linkedExtra farm runoff in the Mississippi to increase area with no oxygen
Associated Press June 21, 2008
WASHINGTON - Floodwaters loaded with farm runoff are heading down theMississippi River, and scientists fear that the deluge will sharply increase the expected
dead zone this summer in the Gulf of Mexico, covering an area the size of Maryland.
The dead zone is a region of the gulf that becomes starved for oxygen during much of the summer and cannot support fish or other sea life.
There are hundreds of dead zones around the world that wreak havoc on marine ecology and cut off vast areas for commercial fishing. The zone in the gulf
is the largest in the Western Hemisphere.