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32 Cards in this Set
- Front
- Back
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CHaracteristics of Water Molecule
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--Strong covalent bond between O and H
--Weak H bonds between O and H atoms of adjacent molecules - Many unusual thermal and physical properties |
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Properties of water
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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) |
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Changes of State
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-Hydrogen bonds: form condensation break in evaporation (540 cal)
-Solid to liquid(uses 80cal), warming (uses 100cal), liquid to gas (uses 540 cal) |
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Feshwater salinities/ composition
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-low: <0.1ppt)
-dominated by calcium, bicarb, and silicate -exact compostion reflects chemistry of bedrock in watershed |
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Seawater salinites/ composition
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- Dissolved salts 35% (35ppt)
- form ions -major cinstituents: Cl, Na, So4, Mg, Ca, K, HCO3 - these make up >>99% of dissolved salts |
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Processes Governing Ion Content in Seawater
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1. Biological productivity/ sedimentation
2. Calcium carbonate precipitation 3.Atmospheric salt transport 4. Evaporites 5. Ion Excahnge 6. Hydrothermal vent activity |
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Biological Productivity/ Sedimentation
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-Aragonite: type of CaCO3 animals produce
-shells of dead animals trapped in sediments -brought up through tectonic activity |
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Calcium Carbonate precipitation
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-Dissolution of CaCO3 depends on temp and pH (high temp and low pH develop solid)
-causes "whiting" in water (cloudy with solid CaCO3) |
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Atmospheric salt transport
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-at oceans: salt in air
-sea sprat (aerosol from waves) |
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Evaporites
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-occurs in closed coastal regions
-water becomes trapped and evaporates, leaving salts behind |
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Ion exchange
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-Ions associated with particles in water (typically neg charge)
-attracts pos ions to soil particle -takes Ca/Na out of water more than anions |
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Measuring Ions in Water: Freshwater
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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) |
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Measuring Ions in Water: Seawater
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-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 |
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Dissolved Gases in Seawater
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-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 |
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Temp salinity and pressure relations to solubility
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-high temp, low solubility
-high salinity, low solubility -high pressure, high solubility |
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Gas Concentrations at depth
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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) |
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Freshwater Littoral Zone
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portion of lake where light penetrates to bottom
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Macrphytes
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large plants (autotrophs)
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Psammon
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community of organisms living between sand grains on wet endge of lake
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Periphyton
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small plants growing on larger ones
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Limnetic zone
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open water where light does not reach the bottom
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Neuston
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plants and animals living at air/water interface
Ex: duckweek, water strider) |
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Profundal Zone
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very bottom of lake
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Marine Systems: water zones
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Intertidal: portion between high and low tidea
Pelagic: open water Benthic: light doesn't penetrate Abyssal:deepest portions of ocean |
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Upwelling
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where water travels up to surface from bottom
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Coriolis Force
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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) |
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Ekman Spiral
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-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 |
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Dinoflagellates
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-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) |
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Diatoms
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-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 |
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Coccolithophorids
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-marine only
-covered with CaCO3 plates (coccoliths) - found >100m -plates build up on bottom after organisms die -plates fuse under pressure forming limestone |
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Prymnesiophytes
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-similar to coccolithophorids w/o CaCO3 plates
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Cyanobacteria
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-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 |
