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32 Cards in this Set

  • Front
  • Back
CHaracteristics of Water Molecule
--Strong covalent bond between O and H
--Weak H bonds between O and H atoms of adjacent molecules
- Many unusual thermal and physical properties
Properties of water
1.Cohesion (surface tension, viscosity): H bonds hold water molecules together, order structure at air/water interface, low resistace to flow
-Heat Capacity: high 1cal/g/deg C, critical for Earth's temp reg
- Compressibility: very low, volume reduced by 1.7% at 400 atm (4km deep)
-Dissolving ability: separates charged ions, continually transports salts to ocean
- Density: ice less dense, max density at 3.98C (decreases due to molecule arangement in crystalline structure), salt precip out of water during freezing (ice less salty than water)
Changes of State
-Hydrogen bonds: form condensation break in evaporation (540 cal)
-Solid to liquid(uses 80cal), warming (uses 100cal), liquid to gas (uses 540 cal)
Feshwater salinities/ composition
-low: <0.1ppt)
-dominated by calcium, bicarb, and silicate
-exact compostion reflects chemistry of bedrock in watershed
Seawater salinites/ composition
- Dissolved salts 35% (35ppt)
- form ions
-major cinstituents: Cl, Na, So4, Mg, Ca, K, HCO3
- these make up >>99% of dissolved salts
Processes Governing Ion Content in Seawater
1. Biological productivity/ sedimentation
2. Calcium carbonate precipitation
3.Atmospheric salt transport
4. Evaporites
5. Ion Excahnge
6. Hydrothermal vent activity
Biological Productivity/ Sedimentation
-Aragonite: type of CaCO3 animals produce
-shells of dead animals trapped in sediments
-brought up through tectonic activity
Calcium Carbonate precipitation
-Dissolution of CaCO3 depends on temp and pH (high temp and low pH develop solid)
-causes "whiting" in water (cloudy with solid CaCO3)
Atmospheric salt transport
-at oceans: salt in air
-sea sprat (aerosol from waves)
Evaporites
-occurs in closed coastal regions
-water becomes trapped and evaporates, leaving salts behind
Ion exchange
-Ions associated with particles in water (typically neg charge)
-attracts pos ions to soil particle
-takes Ca/Na out of water more than anions
Measuring Ions in Water: Freshwater
1.Total Dissolved Soilds (TDS) - weight of material remaining after evaloprating a filtered sample of known volume
-unites = mg/L
2. Specific COnductance - measures the ability of water sample to conducte electricity
-units = uS/cm (microseimens)

TDS = 0.65 * Spec. Cond (can be used in conductances <1000uS/cm)
Measuring Ions in Water: Seawater
-Expressed as ppt (g/Kg) or psu (practical salinity unit)
1. TDS - not practical
2. Hydromenter: infer salinity fron density
3. Specific COnductance: meter automatically converts conductance to salinity
4. Refractometry: water's ability to "bend" light proportional to salinity
5. Chlorinity: determine total halide content by tritrating with silver nitrate
Dissolved Gases in Seawater
-Gases dissolve & exsolve at air/water interface
-Surface water saturated w/ atmospheric gases
-different equilibrium concentrations for diff gases
-major gases: N2, Co2, O2
-Saturation affected by temp, salinity, and pressure
Temp salinity and pressure relations to solubility
-high temp, low solubility
-high salinity, low solubility
-high pressure, high solubility
Gas Concentrations at depth
1. O2: typically 0-10mL/L in ocean, O2 minimum occurs at intermediate depths (800m), O2 renriched at surface, depleated intermediate, replendished at depth

2. CO2: Depleted at surface water, replenished at depth; biological pump cycles CO2 to deep ocean (caCO3)
Freshwater Littoral Zone
portion of lake where light penetrates to bottom
Macrphytes
large plants (autotrophs)
Psammon
community of organisms living between sand grains on wet endge of lake
Periphyton
small plants growing on larger ones
Limnetic zone
open water where light does not reach the bottom
Neuston
plants and animals living at air/water interface
Ex: duckweek, water strider)
Profundal Zone
very bottom of lake
Marine Systems: water zones
Intertidal: portion between high and low tidea
Pelagic: open water
Benthic: light doesn't penetrate
Abyssal:deepest portions of ocean
Upwelling
where water travels up to surface from bottom
Coriolis Force
due to earth's rotation, water flows to R in N.H. and L in S.H.
-Responsible for coastal upwellings (current moves at 90o from land, makes space for water to move up from depth)
Ekman Spiral
-water at greater dpeths affected more by Coriolis force
-forms spiral by depth
-average flow of water is 90o to the wind direction (parralles coast)
-water moves from high pressure depths to low pressure surface
Dinoflagellates
-phytoplanton
-have hard covering of cellulose plantes
-diagnositic in IDing species
-from vegetative/ normal state can encyst and sink to bottom to survive stress
-Some: autotrophic, heterotrophic, mixotrophic (have chlorophyll but uptake sugar)
Some kleptochloroplastic, toxin-forming, bloom-forming, capable of vertical migrations
-found in symbiosis with: sean anemones, coral (inside cells) and giant clams (in "blood" not cells)
Diatoms
-no flagella
-regular shapes: pennate or centric
-covered with frustrule (2 overlapping silica values held together by membrane)
-frustrule very durable, remains in sediment
-able to detrmine what part diatom pops were by examining sediemtns
-Pennate usually benthic (move using raphe (central groove) which produces mucus and allows movement
-Cnetric usually planktonic
Coccolithophorids
-marine only
-covered with CaCO3 plates (coccoliths)
- found >100m
-plates build up on bottom after organisms die
-plates fuse under pressure forming limestone
Prymnesiophytes
-similar to coccolithophorids w/o CaCO3 plates
Cyanobacteria
-blue-green algae
-more prevalent in freshwater than marine
-some are N fixing (NH2 -> NH3)
-contain Nitrogenase (enable N fixing (anaerobic process, O2 interferes with enzyme)
-Heterocysts: large, thich walled called without chlorphyll, present in some algae and used as a site for N fixation
-source of new Nitrogen