SEA WATER SEA WATER ENVIRONMENTENVIRONMENT

OCEANS OCEANS The earth’s oceans make up The earth’s oceans make up more than 70% of its total more than 70% of its total

surface area.surface area.

OCEANS OCEANS Global oceans participate in the global Global oceans participate in the global energy balance ...energy balance ... by transporting heat energy, which is preferentially received in the tropics by solar radiation, toward the polar regions. Over half of the solar energy reaching the earth is first absorbed by oceans and then transmitted to other regions.

OCEANS OCEANS Global oceans take excess COGlobal oceans take excess CO22 from from the atmospherethe atmosphere ......

at a rate that depends on ocean at a rate that depends on ocean temperature. temperature. The partial pressure of CO2 in cold water is depressed by enhanced solubility and (in the spring bloom) phytoplankton growth making cold water a sink for atmospheric CO2 .

OCEANS OCEANS Global oceans play a significant role in Global oceans play a significant role in determining where and how much determining where and how much water vapor enters the atmospherewater vapor enters the atmosphere which in turn influences the global energy balance. Ocean processes are slow in comparison to atmospheric processes, so changes in ocean structure can introduce slow changes of climate.

OCEANS OCEANS There are actually just three distinctly separate oceans There are actually just three distinctly separate oceans in the world today: the World Ocean, the Black Ocean in the world today: the World Ocean, the Black Ocean and the Caspian Sea.and the Caspian Sea.

The largest ocean on earth is the World Ocean, which is continentally divided into five smaller parts, which include the Atlantic Ocean, the Pacific Ocean, the Indian Ocean, the Arctic Ocean and the Antarctic Ocean. Smaller portions of these oceans are typically classified as either seas, gulfs or straits.

The Mediterranean Sea unofficially became the world’s fourth ocean.

OCEANS OCEANS Pacific OceanPacific Ocean

the largest ocean; covers 35% of the earth; is almost half of all the oceans, as big as the other four oceans combined. As the earth spins around, there is a viewpoint from outer space where all you can see is the Pacific Ocean.

Atlantic OceanAtlantic Ocean

is the second largest ocean; covers 21% of the earth; is a little bigger than half as big as the Pacific Ocean.

PACIFIC YESTERDAYPACIFIC YESTERDAY

OCEANS OCEANS Indian OceanIndian Oceanis the third largest ocean; covers 15% of the earth.

Antarctic OceanAntarctic Oceanalso called the Southern Ocean; circles the globe and surrounds the southern continent of Antarctica.

Arctic OceanArctic Oceancovers the earth's north pole; is so cold that its surface is often frozen during the winter.

SEA WATER SEA WATER

PropertiesProperties- physical- physical- chemical- chemical- biological- biological

TemperatureTemperature

Tropical ocean water is warm, provides a stable environment for solidified calcium carbonate. Corals, clams and other sea creatures make hard body parts from calcium carbonate salts

dissolved in the water. Solidified calcium carbonate tends to dissolve faster in cold water.

VERTICAL MIXING

Equatorial surface currents collect heat, which is ultimately shed to the Equatorial surface currents collect heat, which is ultimately shed to the atmosphere by the time the surface currents reach the North Atlantic. Once atmosphere by the time the surface currents reach the North Atlantic. Once

cooled, the water sinks to the ocean bottom, reemerging ahundred or more years cooled, the water sinks to the ocean bottom, reemerging ahundred or more years later in the Indian or Pacific Oceans.later in the Indian or Pacific Oceans.

RESIDENCE TIMES OF WATER

Reservoir Typical residence timesGlaciersSeasonal Snow Cover Soil Moisture Groundwater: Shallow Groundwater: Deep Lakes Rivers

20 to 100 years2 to 6 months1 to 2 months100 to 200 years10,000 years50 to 100 years2 to 6 months

SEA WATER SEA WATER

SEA WATER SEA WATER

Sea water has been defined as a weak solution of almost

everything !

COMPOSITION COMPOSITION

Water in oceans and Water in oceans and seas is salty !seas is salty !

Salt builds up in the ocean because the only way water can leave the ocean is

through evaporation. And when the water evaporates it doesn't take the salt with it.

Salts dissolved in sea waterSalts dissolved in sea water

55% Cl55% Cl30,6% Na30,6% Na

7,7% SO7,7% SO44

3,7% Mg3,7% MgCaCa KK Minor saltsMinor salts

Six major ions make up >99% of the total Six major ions make up >99% of the total dissolved in seawater.dissolved in seawater.

They are sodium ion (Na+), chloride (Cl-), sulfate (SO4

2-), magnesium ion (Mg2+), calcium ion (Ca2+), and potassium ion (K+).

SALINITYSALINITY

Salinity is related to the concentration of dissolved salts in seawater.

Salinity has no units. The PSU or "practical salinity unit" is incorrect, although frequently used. Salinity is approximately equal to the weight, in grams, of salt dissolved in 1000 g of seawater. This would be the salt concentration in parts per thousand (o/oo).

COMPOSITIONCOMPOSITION

One of the most baffling questions in modern science is why

the oceans maintain an almost the oceans maintain an almost constant compositionconstant composition

including every element known to man. And these proportions never

seem to change.

COMPOSITION IS COMPOSITION IS CONSTANT CONSTANT

CONCENTRATION IS DIFFERENT

Average salinity of the oceans is 35 Average salinity of the oceans is 35 oo//oo.oo.

The saltiest water (40 o/oo) occurs in the Red Sea and the Persian Gulf, where rates of evaporation are very high. Of the major oceans, the North Atlantic is the

saltiest; its salinity averages about 37.9 o/oo. Low salinities occur in polar seas where the salt water is diluted by melting ice and continued precipitation.The Baltic Sea ranges in salinity from about 5 to 15 o/oo. The salinity of the Black Sea is less than 20 o/oo.

SALINITYSALINITY

SALINITY CHANGESSALINITY CHANGES

CONSEQUENCES OF CONSEQUENCES OF CONSTANT COMPOSITIONCONSTANT COMPOSITION

Measure Cl-concentration and ... calculate salinity because of seawater's constancy of chemical composition, the total salinity can be determined from the concentration of the chloride

ion since the ratios of sodium to chloride to magnesium to calcium and to any other major constituent remain constant

SEA WATER AND RIVER WATERSEA WATER AND RIVER WATER

obviously are very different from obviously are very different from each othereach other

(1) Sodium and chloride (the components of common table salt) constitute a little more than 85 % of the dissolved solids in ocean water and give to the water its characteristic salty taste, but they represent less than 16 % of the salt content of river water.

SEA WATER AND RIVER WATERSEA WATER AND RIVER WATER

obviously are very different from obviously are very different from each othereach other

(2) Rivers carry to the sea more calcium than chloride, but the oceans nevertheless contain about 46 times more chloride than calcium.

SEA WATER AND RIVER WATERSEA WATER AND RIVER WATER

obviously are very different from obviously are very different from each othereach other

(3) Silica is a significant constituent of river water but not of sea water.

SEA WATER AND RIVER WATERSEA WATER AND RIVER WATER

obviously are very different from obviously are very different from each othereach other

(4) Calcium and bicarbonate account for nearly 50 % of the dissolved solids in river water yet constitute less than 2 % of the dissolved solids in ocean water.

GASESGASESIN THE OCEANSIN THE OCEANS

COCO22

Carbon dioxide is considered a trace gas in the atmosphere because it is much less abundant than oxygen or nitrogen. However, this trace gas plays a vital role in sustaining life on Earth and in controlling the Earth's climate by trapping heat in the atmosphere.

OCEAN IS A SINK FOR COOCEAN IS A SINK FOR CO22

The oceans play an important role in regulating the amount of CO2in the atmosphere because CO2 can move quickly into and out of the oceans. Once in the oceans, the CO2 no longer traps heat. CO2 also moves quickly between the atmosphere and the land biosphere (material that is or was living on land).

Of the three places where carbon is stored — atmosphere, oceans, and land biosphere — approximately 93 % of the CO93 % of the CO22 is found in the is found in the oceans. oceans.

OxygenOxygen dissolves in ocean surface water from the atmosphere. Photosynthesis is also a source of oxygen to ocean surface waters. Oxygen is consumed by respiration. Rarely, animals and bacteria use all of the oxygen in sub-surface waters, which become anoxic. This can only happen if the waters are isolated from the atmosphere in some way.

Carbon dioxideCarbon dioxide is consumed during photosynthesis and released during respiration. It can also be exchanged with (dissolved from and released to) the atmosphere. Carbon dioxide can react with water to form bicarbonate and carbonate ions.CO2 + H2O HCO3

- + H+ CO32- + 2H+

These reactions control the acidity (pH) of seawater.

pH of sea waterpH of sea water

pH of sea waterpH of sea water

CO2 + H2O HCO3

- + H+

CO32- + 2H+

these reactions control the acidity (pH) of water

pH of sea waterpH of sea water

normal pH values in seawater are about normal pH values in seawater are about 8.2 at the surface and decrease to about 8.2 at the surface and decrease to about

7.7 in deep water7.7 in deep water

the different salts in sea water tend to buffer the water

HYDROLOGIC OPTICS

Hydrologic optical principles determines the penetration of

biologically damaging ultraviolet light underwater.

HYDROLOGIC OPTICS

The depth to which sunlight penetrates into the water determines the transparency of a water

body. Light penetration is dictated by the composition of the water. Water itself strongly

absorbs light in the red region of the light spectrum, which is why clean, clear waters are

blue. Other components in the water that impact its optical properties, include colored dissolved

organic matter (CDOM), decaying organic matter, inorganic particulate matter, such as silt and clay,

and phytoplankton.

At about 20 feet deep, this diver's red weight belt is At about 20 feet deep, this diver's red weight belt is nearly colorless, while the color in his blue flotation nearly colorless, while the color in his blue flotation

vest is solid and true.vest is solid and true.

LIGHT PENETRATION

Light from the sun

TOTAL SUSPENDEDTOTAL SUSPENDEDSOLIDS (PARTUCULATES)SOLIDS (PARTUCULATES)

DISSOLVEDDISSOLVEDORGANICSORGANICS

PHYTOPLANKTONPHYTOPLANKTON

A b s o r b e d l i g h tA b s o r b e d l i g h t

ScatteredScatteredlightlight

The intensity of this light decreases rapidly The intensity of this light decreases rapidly with water depth, for example:with water depth, for example:

* only only 73%73% of the surface light reaches a depth of of the surface light reaches a depth of 1 centimeter1 centimeter

* only only 44.5%44.5% of the surface light reaches a depth of the surface light reaches a depth of of 1 meter1 meter

* 22.2%22.2% of the surface light reaches a depth of of the surface light reaches a depth of 10 10 metersmeters

* 0.53%0.53% of the surface light reaches a depth of of the surface light reaches a depth of 100 meters100 meters

* 0.0062%0.0062% of the surface light reaches a depth of of the surface light reaches a depth of 200 meters200 meters