Cycling of Matter

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Cycling of Matter
in ecosystems
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Biogeochemical Cycles

• Recall The particles that make up matter cannot
  be created or destroyed.
• This means that all water and nutrients must be
  produced or obtained from chemicals that already
  exist in the environment.

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Biogeochemical Cycles

• This happens in a series of cycles in which
  chemicals are continuously consumed, rearranged,
  stored and used.
• Because these cycles involve living (bio)
  organisms and occur on Earth (geo), they are
  called biogeochemical cycles.

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Biogeochemical Cycles

• Every particle in every organism is part of a
  biogeochemical cycle!

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The Water Cycle

• Water cycle the series of processes that cycles
  water through the environment
• Most of the water that is present in the water
  cycle is found in the abiotic environment.

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The Carbon Cycle

• Carbon moves between the abiotic and biotic parts
  of an ecosystem in the carbon cycle.
• Most of this exchange occurs between carbon
  dioxide (either in the atmosphere or dissolved
  in water) and photosynthesizing plants and micro
  organisms.

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Carbon Deposits

• While large quantities of carbon cycle through
  photosynthesis and cellular respiration, most of
  Earths carbon is not cycled.

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Carbon Deposits

• Instead, it is stored in carbon-rich deposits
  such as fossil fuels (coal, oil, natural gas
  etc.) that form when decomposed organisms are
  compressed over millions of years.

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• Carbon is also stored for millions of years as
  limestone formed from dead marine organisms.

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Carbon Deposits

• Large quantities of carbon are also contained in
  plant tissue and as dissolved carbon dioxide in
  the worlds oceans.

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Carbon Deposits

• These locations are referred to as carbon sinks
  because carbon can enter or leave them over
  relatively short periods of time.

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Human Impact

• Human activities have a dramatic impact on the
  carbon cycle.
• By burning fossil fuels, humans release the
  stored carbon into the atmosphere, which is
  contributing to global climate change.

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• Deforestation also increases the concentration of
  carbon dioxide in the atmosphere.

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Nitrogen Cycle

• Nitrogen is extremely abundant in the atmosphere,
  however it is not easy to acquire directly from
  the abiotic environment.

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Nitrogen Cycle

• Nitrogen enters and leaves the atmosphere through
  a complex biochemical pathway called the nitrogen
  cycle.

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Nitrogen Cycle

• Most of the nitrogen used by living things is
  taken from the atmosphere by certain bacteria in
  a process called nitrogen fixation.

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Nitrogen Cycle

• These micro-organisms convert nitrogen gas into a
  variety of nitrogen-containing compounds,
  including nitrates, nitrites and ammonia.

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• Lightning and UV light also fix small amounts of
  nitrogen.

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Nitrogen Cycle

• In addition, humans add nitrogen to the soil as
  fertilizer.

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Nitrogen Cycle

• Once in the soil ecosystem, the nitrogen-rich
  compounds are available to producers.
• After the nitrogen is absorbed, it is passed from
  producer to consumer and moves up the food chain.

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Nitrogen Cycle

• Many animals consume more nitrogen than they can
  use, and excrete the excess in the form of urea
  or ammonia.

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• A dead organisms nitrogen-rich compounds are
  taken in by decomposers, or are released back
  into the environment.

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Nitrogen Cycle

• These compounds are either recycled again by soil
  micro-organisms, or they are converted by
  denitrifying bacteria back into nitrogen gas
  which then re-enters the atmosphere.

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