Ecology APES Cycles

The Carbon Cycle

The Carbon Cycle includes the movement of molecules that contain (Co2, glucose, CH) between sources and sinks +some steps are very quick (FF combustion) some are very slow (sedimentation + burial) + leads to imbalance in which reservoirs or sinks are storing carbon

• atmosphere is key c reservoir": increasing levels of c in ATM. leads to global warming

Carbon Sink

A carbon reservoir that stores more carbon than it releases

• Ocean (algae, sediments, plants, soil)

Carbon Source

Processes that add c to ATM.

• Fossil fuel (Oil, Coal, Natural gas)

• Animal ag.(cowburps+farts)

• Deforestation releases (C02 from trees)

Fossil Fuels

Coal,oil, and Natural Gas are formed from fossilized remains or organic matter Ex) dead ferns (Coral) or marine algae and plankton (oil)

Steps of the Carbon Cycle

1. Producers convert C02 into sugars

2. Sugars are converted back into C02

3. Some carbon can be buried

4. Human extraction of fossil fuels brings carbon to earths surface were it can be combusted

5. C02 in the atmosphere and C02 dissolved in water are constantly exchanged

6. Combustion converts fossil fuels and plant material into C02

Photosynthesis and cellular respiration

• plants and algae phytoplankton

• Removes C02 from ATM.

• Atmosphere converts it into glucose

• Glucose= biological form of c and stored chemical energy in form of sugar

• Co2

• Done by plants and animals to released stored energy

• uses co2 to break glucose down and release energy

• Co2 source (Adds C02 to ATM.)

• Both processes are very quick

• Cycle c between biosphere and atmosphere in balanced amount (No net c increase ATM.)

The Nitrogen Cycle

The nitrogen cycle includes the movement of molecules that contain

• Movement of N containing molecules between sources and sinks/reservoirs

sources release N into atmosphere; sinks take n out of the atmosphere increasing amounts

• N reservoirs hold N for a relatively short period of time compared to the c cycle. Ex) Plants, Soil, atmosphere

• Atmosphere - main N reservoir, N in ATM exists mostly as N2 gas not usable by plants or animals, N= critical plant+ animal nutrient

Human Impacts

• Climate N20 (Nitrous oxide)= greenhouse gas which earths climate produced by dentrification of nitrate in agricultural soils.

• Ammonia volatization,excess fertilizer use can lead to NH3 gas entering atm.

• Leaching and Eutrophication: synthetic fertilizer use leads to nitrates (No3) leaching, or being carried out of soil by water.

Nitrogen Cycle Steps

Nitrogen Fixation: Process of N2 gas being converted into biologically available (usable by plants) NH3 (Ammonia) or N02 - (Nitrate)

Biotic Fixation: certain bacteria that live in the soil or in symbiotic relationship with plant root nodules, convert N2 into ammonia (NH3) Rhizobacterial live in root nodules of ligumes (Peas+Beans) and fix N for them in return for amino acids from the plant

Abiotic Fixation: Free-living microorganisms fix nitrogen independently in the soil or water without a host plant.

Other Nitrogen Cycle Steps

• Assimilation: plants and animals taking N and incorporating it into their body, plant roots in N03 or NH3 from soil; animals assimilate N by eating plants of other animals.

• Ammonification: Soil,Bacteria,Microbes and decomposers converting waste and dead biomass back into NH3 and returning it into soil

• Nitrification: Conversion of NH4 into nitrate No2 and then nitrate No2 by soil Bacteria

• Dentrification: Conversion of soil N (NO3) into nitrous oxide (N20) has which returns to the atmosphere

The Phosphorus Cycle

Movement of P atoms and molecules b/w sources and sinks/Reservoirs

Phosphorus Sources

Major natural source of P is weathering of rocks that contain P minerals

Assimilation & Excretion/Decomposition

• Absorbed by plant roots and assimilate into tissues; animals assimilate P by eating Plants or other animals

• Form a mini-loop within P cycle just like assimilation and amonification in N cycle photosynthesis and resp. in C cycle

Sedimentation & Geologic Uplift

• Phosphate doesn’t dissolve very well into water; much of it forms solid bits of phosphate that fall to the bottom as sediment (Sedimentation)

• P sediments can be compressed into sedimentary rock over long time periods by pressure of overlying water

Eutrophication (Too much Nitrogen and/or Phosphorus)

Too much Nitrogen and/or Phosphorus→Algae bloom covers surface of water,blocking sunlight+killing plants below the surface → Algae die off, bacteria that break down dead algae use up o2 in water b/c decomp = arobic process → Lower o2 levels (Dissolved oxygen) in water kills aquatic animals especially fish → Bacteria use up even more o2 to decompose dead aquatic animals → Creates Pos feedback loop less o2 means more dead organisms and more decomposition to less o2 again

Steps of the Phosphorus Cycle

1) weathering of uplifted rocks contributes phosphates to the land. Some phosphates make their way back to the ocean

2) Phosphate fertilizer applied to fields can run off directly into streams, become part of soil pool, or be absorbed by plants

3) Excretion by animals and decomposition of both animals and plants release phosphates on land or water.

4) Dissolved phosphates precipitate out of solution and contribute to the ocean sediments. conversion of sediments into phosphate rocks is a very slow process

5) Geologic forces can slowly lift up phosphate rocks from the ocean floor to form mountains

The Hydrolologic (water) cycle

• movement of H20 (in different states) b/w sources and sinks

• State or matter (Solid/liquid/gas) as well as where water is moving are key H20 cycle

• Ex: Precipitation= ATM (gas)→ land or surface water (liquid)

• Energy From sun drives the H20 cycle Ex) heat from sun causes liquid water in ocean to become a gas (evaporation) in ATM.

• Ocean=largest water reservoir

• Ice caps and groundwater are smaller reservoirs but contain fresh usable water for humans

Transpiration + Evapotranspiration

Transpiration: Process plants use to draw groundwater from roots up to leaves

Evapotranspiration: Amount of H20 that enters ATM. from transpiration and evap. Combined

• Both driven by the sun

Runoff and Infiltration

Precipitation (Rain) either flows over earths surface into a body of water (runoff) or trickles through soil down into groundwater aquifiers (Infiltration)

• Ground water aquifiers + surface waters (lakes/rivers) are important freshwater reservoirs for Humans+Animals.

Steps of water cycle

1) Groundwater can flow up to plant uptake

2) Transpiration

3)Evaporation)

4)Precipitation

5)Surface runoff

6) infiltration into groundwater

7)Aquifier to groundwater flow

8) evaporation

9) condensation

10) surface runoff