FRESHWATER MID

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