• nitrogen 
• oxygen
• sulfur
• water
• carbon (functionally)
• sulfur (functionally)

give examples of imperfect cycles mentioned in powerpoint:

• phosphorous
• magnesium
• iron
• calcium 
• potassium 

1. release from rocks through weathering
2. loss of nutrients to aquatic ecosystems through leaching
3. recirculation of nutrients through terrestrial and aquatic ecosystems. 
4. release to atmosphere and fixation or return from the atmosphere
5. loss for long periods as ocean sediments

Nitrogen cycle

The global nitrogen cycle is unique in that it consists of:

1. a large well-mixed pool of N2 in the atmosphere
2. a smaller quantity of nitrogen bonded to carbon, oxygen, and/or hydrogen that cycles among plants, animals, soils, sediments, & solutions
3. a set of relatively small, largerly biologically mediated transfers among these pools

1. in order fo rthe bacteria to proliferate in the soil they must have a source of carbon, that is, a substrate
2. since the reduction of nitrogen from N2 ot NH4+ must take place in an anaerobic environment within the nodule, the amount of oxygen is closely regulated

fill in the blank:

When ___ _____ is taking place, the ____ appear to red, which is an indiciation of the presence of ____ molecules

This form of nitrogen is not very reactive and must be fixed (made into ammonia or oxides of nitrogen), either by high-energy fixation (lightning, cosmic radiation, etc) or by biological fixation.

this is the breakdown of protein and amino acids to CO2 and NH3

it is a function of decomposter organisms, but all eukaryotic cells can accomplish it as well.

• nitrosomonas: is able to oxidize ammonium to nitrite (NO2-), releasing energy for use by the bacterium
• nitrobacter: can oxidize nitrite further to nitrate (NO3-). Plants readily take up these compounds, especially nitrate

1. first, the main reserves of phosphate are in rock, from which elements are leached for biological uptake
2. second, its movement is linked directly with the movement of water (called the hydrologic cycle)

the sulfur cycle is another complex cycle, similar to that of carbon, in which there are significant terrestrial desposits, but there are also actively circulating atmospheric components

• S2
• SO2
• H2S

the carbon cycle is a gaseous cycle with sedimentary components

*It is tied to energy flow in ecosystems. 

Carbon cycle

dominant forms

1) land masses inorganic:

• mostly carbonate compounds
• limestone (calcium carbonate, CaCO3)
• dolomite (magngeisum carbonate, MgCO3)

carbon cycle:

dominant forms

2) Land Masses Organic origin:

• fossil fuels (coal, peat, oil, shale)
• living organic material (cellulose, lignin, fibers, etc. in leaves and wood)

carbon cycle:

1) Atmosphere

2) Oceans

1) Atmosphere: carbon dioxide gas

2) oceans: dissolved carbon dioxide, biomass, carbonate ions (CO32-)

• precipitation
• particulate fallout from atmosphere (dust)
• biotic immigration
• fixation from atmosphere
• weathering of substrate
• human effects: pollution and fertilizer applications 

From the Hubbard Brook study, what are exports?

• run-off and stream outflow
• particulate loss by wind erosion
• biotic emigration
• release to the atmosphere 
• loss by leaching to lower soil layers beyond root zone
• human effects: harvest of forest