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Ponds
Are small (< 5 ha, 2.5 acres), shallow (< 5 m), permanent or temporary, natural or human made, with < 30% emergent vegetation (70% open water)
Streams
Kill comes from Middle Dutch kille meaning "riverbed" or "water channel“(Catskills, WallKill, FishKill, etc)
Ice Off
The first day were the ice is completely melted
Ice On
First day with 100% ice cover
Linear Regression Line
y = m*x + b
y = Dependent variable: Day of ice-off
m = Slope of line: Day/Year (-) = getting earlier (+) = getting later
x = independent variable: Year
b = Intercept: Day of the year
What is shown by the R2 value?
R2 close or equal to ~0: 0% of variance
R2 close or equal to ~1: 100% of variance: perfect line
Properties of water
1.) Chemical and physical properties
2.) Relationships among water viscosity, inertia, and physical parameters
3.) Movement/ forces of movement of water
Chemical and physical properties of water
1.) Hydrogen bonding (polarity, dipolar)
2.) High density, surface tension, heat of vaporization, heat capacity, liquid at earth’s surface, excellent solvent (important for weathering)
3.) Ions more soluble in warmer water, gasses less
4.) Unusual relationship between temperature and density
How can lizards and other creatures walk and run on water?
Due to high surface tension
Why is measuring temperature at depth important?
Able to determine mixing
If the temperature is isothermal throughout the profile, we can assume that the water column is able to mix
Why is mixing important?
Oxygen
Nutrients
Organisms and other particles
Thermocline
Its the depth of the lake where the temperature changes the most
As the lake gets warmer, thermocline gets shallower.
Epilimnion
Top of the lake
Metalimnion
Middle of the lake
Hypolimnion
Bottom of the lake
Why is there warmer water at the surface?
Because it is less dense
Stability
The degree of which lake stratification resists mixing by wind.
Stability depends on the difference in density between layers
Schmidt Stability
Quantity of work required to mix the entire volume of water to a uniform temp.
Dimictic
two periods of mixing per year:
summer stratification
fall turnover (mixing)
winter inverse stratification
spring turnover (mixing)
Typical of northern latitudes:
Must have winter ice cover.
Monomictic
On period of mixing
Warm monomictic
Stratifies in the summer and mixes all winter
no ice
Cold monomictic
Stratifies in the winter and mixes in the summer
has ice cover
Polymictic
Mixes frequently throughout the year
Amictic
Never mixes, always stratified
ALWAYS covered in ice
Oligomictic
Thermally stratified much of the year, but cools for rare short mixing periods
Usually the tropics
The buoys of GLEON
Sensor platforms from around the world
Used to measure max depth, and surface area of a lake.
Why is light important to lakes?
Photosynthesis driven by light
UV increases are important
Water is heated by light
Oligotrophic lake
Blue colored lake
Eutrophic lake
Contain very high concentrations of phytoplankton (microscopic plants) and the water is green
Light is Attenuated More Rapidly in Eutrophic Lakes
Tea colored lake
Due to all the dissolved organic carbon flowing into the lake
ABSORBS ALL THE COLORS
Example.) Glacial flour from melting glacier with rocks and slit and clay particles gets distributed with the water molecules, it’s reflecting light back so that’s why it’s that color.
Absorption
Conversion of light to heat
Transmission
Amount of light left after absorption
Attenuation
Diminution of light energy with depth due to absorption and scattering
Secchi Disk
Measures transparency
Telling us what color = age
Depth = Secchi depth
What is hard vs. easily dissolved in water?
Easy: Ca, Na ions
Hard: Fe, Mn ions
How does temperature effect dissolved ions?
Ions are more soluble in warmer water
In most salts, the addition of more heat facilitates the dissolving reaction
Provides more energy to break bonds in the crystal structure.
How does temperature effect dissolved gasses?
At warmer water, molecules are moving faster, less soluble
Gases are more likely to escape attraction
Return to gas phase
Why does the Dead Sea have stratification?
Halocline – salt-based stratification
Salty water is way more dense than freshwater
Hypersaline – when salt cannot evaporate = become salt deposits and stay on the edge of the salt lake, salt is now used for health care purposes and for food (Dead Sea)
Redox Potential is measured in?
Free electron availability
High = few available electrons
Low = lots of available electrons
Eh (measured in mV)
How does dissolved oxygen effect redox reactions?
because it has high affinity for free electrons (electron acceptor)
If DO is present, redox is high, oxidizing environment
If DO is not present, redox is lower, but still can have oxidation of organic carbon with inorganic electron acceptors other than O2
When oxygen is present redox reactions are?
high
Lower numbers of free electrons in solution.
When oxygen is depleting redox reactions are?
low
Increased number of free electrons in solution
Redox and biotic processes
Oxidation reactions yield energy under oxidizing conditions. Ammonium high, Nitrate low
Reduction reactions yield energy under reducing conditions. Ammonium low, Nitrate high
Reverse reactions require energy inputs.
Microbe Mediated Redox Reactions
Oxidation and reduction reactions are “Coupled”; one needs the other!
Many reductions here couple with the oxidation of organic matter, even when there is no O2 in the environment.
When the oceans get more acidic, what happens to bicarbonate?
Becomes carbon dioxide
Acidity becomes lower
What happens to seashells made of calcium carbonate (CaCO3)?
Dissolve and go left to be more acidic and become carbon dioxide
Feedback loop
Sources of carbon
Atmosphere
Weathering reactions
Plants, biomass/organic carbon via photosynthesis
Respiration
Sinks of carbon
Atmosphere: degassing of the atmosphere
Burial in sediments
Export (outlets, GW): Lake Sunapee/Groundwater (losing system)/water table is lower
Transformation of carbon
Respiration
Oxidation
Fermentation
Methanotrophy
Methanogenesis
Oxygenic and anoxygenic photosynthesis
Fermenation
No outside electron acceptor
Organic molecules used as acceptor
Products are often organic acids
Methanotrophy
are aerobic organisms that oxidize methane and carbon monoxide.
Very important in global carbon cycle
Methanogenesis
make methane from CO2 and H2 at very low redox.
Important in global methane cycle
Phosphorus cycle
Phosphorus is a major constituent of nucleic acids, phospholipids, and ATP
The largest reservoirs are sedimentary rocks of marine origin, the oceans, and organisms
NO gaseous P
Forms of phosphorus
Total P (TP)
Dissolved Inorganic P
Dissolved organic P (DOP)
Breakdown products of living/decomposing organisms
Particulate organic phosphorus (POP)
Organic chemicals in living or decomposing organisms
NO gaseous form of P
Phosphorus Enrichment Feedback Loop
TP is mostly tied up in biomass in epilimnion
Phosphate cycles rapidly so is often below detection
Phosphate builds up in de-oxygenated hypolimnia (internal loading)
Entrainment can transport P into epilimnion
What is Nauru
Coral atoll (bathroom break for marine birds) over 1 million years ago
Bird waste from other locations, baking in tropical sun, under tropical forests becomes pure phosphate
Started about 1960s, strip mining for P ensued
1990s bubble burst – P deposits were finite resource
Now most of Nauru is missing, down to coral skeleton
Other Sources of Phosphorus
Non-agricultural fertilizers and eroding sediment from stream banks in urban and suburban areas. Phosphorus often attaches to soil and sediment particles on land, entering surface water years later when stream banks erode.
Manure from agricultural lands
Treated wastewater released from municipal and industrial wastewater facilities
Chemical fertilizers from agricultural lands
Natural sources, including forests and wildlife
Eutrophication
Process where a waterbody exhibits higher concentrations of nutrients and biomass of photosynthetic organisms (e.g., algae)
Especially (P) and (N).
Natural eutrophication
slow-aging process for a water body
time scale: centuries or much longer
Anthropogenic eutrophication
Human activity greatly speeds up the process.
Time scale: decades or shorter
Could occur due to fertilizer run-off, sewage, and industrial waste flowing into lakes.
Structural Metric
Lake attributed measured at a discrete point in time
Assumed to reflect current status or condition of ecosystem
Functional Metric
Capture system dynamics through repeated measurements that quantify processes or rates
Lake Metabolism
A functional metric of lake ecosystem health
Integrated measure of rates of production (GPP) and consumption (R) of organic matter
Gross primary production (GPP)
Refers to the production of biomass by all photosynthesizing organisms per unit time
Total autotrophic conversion of inorganic carbon (CO2) to organic matter via photosynthesis
Driven by algae & plants
Ecosystem respiration (R)
Refers to breakdown of organic matter through aerobic respiration by the whole community (plants, algae, fish, bacteria, zooplankton, etc.) per unit time
Oxidation of organic matter to inorganic carbon (CO2) by both heterotrophic and autotrophic organisms
Driven by algae, plants, bacteria, zooplankton, fish
Viscosity
the resistance to change in form (internal friction)
Inertia
Resistance to a change of a state of motion
Objects traveling fast have greater inertial force
Objects that are dense have greater inertial force
Objects with bigger surface area have greater inertial force
Reynolds Number
Re = Inertia/Viscous
Re goes up with increases in density, velocity, length
Re goes down with increases in dynamic viscosity
Laminar Flow
unidirectional flow
inertia is important
Turbulent Flow
flow in many directions
viscosity is important
Archaea
As different from bacteria as eukarya
Morphologically similar to bacteria
Originally thought to be mainly extremophiles (hyperthermic, halophilic, anaerobic)
Now known to occur in all habitats
Essential in nutrient cycling
Bacteria
Most important organisms in nutrient cycling on earth
Can only culture < 1% of all species
Most species only have few morphologies
Most identification based on metabolic or chemical characteristics
Phytoplankton
Microscopic photosynthesizing organisms
Diatoms
Unicellular & colonial forms
Centric vs. pennate (wing)
Require silica for frustules
Often have large blooms immediately after ice-out
Can be a high-quality food for zooplankton
Chlorophyates/Green Algae
Unicellular, filamentous, and colonial forms
Flagellated & non-flagellated forms
Most are a high-quality food for zooplankton
Dinoflagellates
Unicellular, flagellated
Several are mixotrophic
Photosynthetic
AND eats other organisms
Big concern in marine systems
red tides
brown tides
Chrysophytes
Unicellular & colonial forms
Flagellated
Mixotrophic
Can be a high-quality food, when shape permits
Cryptophytes
Unicellular flagellates
Very high quality food
Increase w/eutrophication
Euglenoids
Unicellular
Some flagellates
Very high quality food
More in eutrophic systems
Cyanobacteria/Blue-Green Algae
Prokaryotes
Unicellular, filamentous, and colonial forms
Many can control buoyancy
Relatively inedible
Conventional wisdom: consequence of eutrophication