15.2 lecture

15.2 Seawater15.2 Seawater

Pages 392 - 398Pages 392 - 398

Goal 1Goal 1

Discuss the chemical and Discuss the chemical and physical properties of physical properties of

seawaterseawater

GasesGases OxygenOxygen NitrogenNitrogen Carbon dioxideCarbon dioxide

NutrientsNutrients NitratesNitrates PhosphatesPhosphates SilicatesSilicates

Salts (see table 15-1 page 392)Salts (see table 15-1 page 392) Salinity 35 ppt = 3.5% Salinity 35 ppt = 3.5% Salt ionsSalt ions

ChlorideChlorideSodiumSodiumSulfateSulfateMagnesiumMagnesiumCalciumCalcium

Salinity Variation (figure 15-10 page Salinity Variation (figure 15-10 page 393)393) High salinity (up to 37 ppt)High salinity (up to 37 ppt)

EvaporationEvaporationHotHotLow precipitationLow precipitation

Low salinity (down to 32 ppt)Low salinity (down to 32 ppt)Low EvaporationLow EvaporationHigh precipitationHigh precipitationFreshwater influxFreshwater influx

Glacier meltGlacier meltRiver mouthRiver mouth

Sources of SaltsSources of Salts Volcanic gasesVolcanic gases Weathered Rocks & MineralsWeathered Rocks & Minerals

Removal of saltsRemoval of salts Precipitate (become solid) in dry Precipitate (become solid) in dry

areasareas Sea Spray deposited inlandSea Spray deposited inland Marine organismsMarine organisms

Physical PropertiesPhysical Properties More dense than freshwaterMore dense than freshwater Freshwater = 1.00 g /mLFreshwater = 1.00 g /mL Seawater = 1.02 g/mL to 1.03 Seawater = 1.02 g/mL to 1.03

g/mLg/mL Freezing point = -2° CFreezing point = -2° C

Light absorption (see figure 15-14 Light absorption (see figure 15-14 page 396)page 396) Seawater absorbs lightSeawater absorbs light RYO (Long wavelengths) 50 mRYO (Long wavelengths) 50 m Green to 100 mGreen to 100 m Photosynthesis ??Photosynthesis ??

Goal 2Goal 2

Explain ocean layeringExplain ocean layering

See page 397See page 397

Warm water = less dense = floatsWarm water = less dense = floats

Cold water = more dense = sinksCold water = more dense = sinks

Temperature decrease with depthTemperature decrease with depth Surface layer (top layer)Surface layer (top layer)

~ 100 m depth~ 100 m depth Nonexistent at polesNonexistent at poles Warm Warm Temperature varies Temperature varies EquatorEquator

Thermocline (middle layer)Thermocline (middle layer) Depth location variesDepth location varies Nonexistent at polesNonexistent at poles Temperature rapidly decreasesTemperature rapidly decreases

Bottom layer (bottom layer)Bottom layer (bottom layer) Depth variesDepth varies Very cold <4° C Very cold <4° C Near freezing tempsNear freezing temps

Goal 3Goal 3

Explain deep water Explain deep water massesmasses

Deep water mass formationDeep water mass formation Polar areasPolar areas

Cold Salty water = very dense Cold Salty water = very dense Salts do not freeze out of waterSalts do not freeze out of waterSinks Sinks Migrates toward equatorMigrates toward equator

Movement of salty water to polesMovement of salty water to polesCoolsCoolsMore salty = more denseMore salty = more denseSinksSinks

Three major water massesThree major water masses

1.1. Antarctic Bottom WaterAntarctic Bottom Water Antarctic winterAntarctic winter Freezing, salt concentrationFreezing, salt concentration ColdestColdest densestdensest

Three major water massesThree major water masses

2.2. North Atlantic DeepwaterNorth Atlantic Deepwater GreenlandGreenland Freezing, salt concentrationFreezing, salt concentration 22ndnd Coldest Coldest 22ndnd Densest Densest

Three major water massesThree major water masses

3.3. Antarctic Intermediate WaterAntarctic Intermediate Water Antarctic winterAntarctic winter Temperature decreaseTemperature decrease 33rdrd Coldest Coldest 33rdrd Densest Densest

Atlantic oceanAtlantic ocean Affected by all 3 deep water Affected by all 3 deep water

massesmasses

Pacific OceanPacific Ocean Affected by only 2 Affected by only 2 Which one does not ???Which one does not ???

THETHE

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