Chemical Cycles in the Ecosystem

By: Marissa Pioso, Amanda Clark, and Harry Cramer

Chemical Cycling: What is it?

• What it sounds like, the cycling of chemicals in an ecosystem

• 3 main cycles: carbon-oxygen, nitrogen, and water• Each cycle has three components:

o Chemicals from the nonliving environment are synthesized into organic compounds by Producers

o Consumers eat the producers, and inorganic chemicals are incorporated into consumers bodies (some chemicals are released as waste)

o Decomposers supply soil, water, air with inorganic chemicals by breaking down dead organisms (the producers gain a new supply of materials, completing the cycle)

Carbon and Oxygen Cycle          Producer Step:• Carbon is found in the atmosphere in CO2 (Carbon Dioxide)

and water in its dissolved form (HCO3-). • Carbon and Oxygen are used during photosynthesis to form

organic compounds• This is why their cycles are often referred to as the Carbon-

Oxygen cycleo Both gases are used in the same processes

(photosynthesis, cellular respiration, breathing etc)           Consumer Step:• Consumers eat plants, and obtain the carbon from the plants• Producers are used as fuel (ie. animals eating plants)

Decomposer Step:• During cellular respiration, organic compounds (sugars)

are broken down, which releases CO2 as waste

Other Sources of CO2:• Breakdown of Detritus (fecal and dead matter), CO2 is

released• Burning Fossil fuels/forest fires also releases CO2

• Volcanoes can release CO2

Carbon and Oxygen Cycle Continued

Nitrogen Fixation• Certain types of bacteria use this process (nitrogen

fixing bacteria)• 80% of atmosphere is N2

• Converts this nitrogen naturally found to ammonium (NH4-)

• Bacteria live in soil, nodules, roots of plants (peas, beans, alfalfa, clover)

Nitrification• Other bacterium convert the ammonium to

nitrates (NO3-) through nitrification

The Nitrogen CycleProducer Step:• Nitrogen fixation and nitrification must occur first (in order for

producers to use nitrogen)• Producers absorb ammonium and nitrates to create nucleic acids,

amino acids, proteinsConsumer Step:• Consumers eat producers and obtain nitrogen (in form of organic

molecules)Decomposer Step:• Some bacteria convert nitrates into nitrogen and release it into the

atmosphere• Nitrogen is released as ammonium from waste and decaying

bodies of organisms• This ammonium then goes through nitrogen fixation and

nitrification and the process repeats itself

Water Cycle• Water evaporates from land and water surfaces resulting from

the heat of the sun and also through transpiration• Transpiration is the evaporation of water from leaves• Through evaporation from the sun and transpiration, water vapor

is added to the atmosphere• Water vapor condenses from the atmosphere, and returns to

earth (soil) as precipitation (rain, sleet etc.)• Plants absorb the water from the soil• Consumers obtain water by eating and drinking• Other water from the atmosphere either runs into rivers/streams

or restores groundwater• This water can re-enter atmosphere through evaporation, and

the cycle repeats***There are not 3 clear components of the water cycle since the water is not produced by an organism, like oxygen, or carbon dioxide, and it is not decomposed in order to begin the cycle once again

Thanks         For           Listening!