biogeochemical cycle

Examples of biogeochemical cycle in the following topics:

• Sources and Sinks of Essential Elements

  • Biogeochemical cycles are pathways by which essential elements flow from the abiotic and biotic compartments of the Earth.
  • Flows of nutrients from living to non-living components of the Earth are called biogeochemical cycles.
  • Ecosystems hinge on biogeochemical cycles.
  • The nitrogen cycle, the phosphorous cycle, the sulfur cycle, and the carbon cycle all involve assimilation of these nutrients into living things.
  • This flow from abiotic to biotic compartments of the Earth is typical of biogeochemical cycles.

• Role of Microbes in Biogeochemical Cycling

  • Microbes form the backbone of every ecological system by controlling global biogeochemical cycling of elements essential for life.
  • Nutrients move through the ecosystem in biogeochemical cycles.
  • A biogeochemical cycle is a pathway by which a chemical element (such as carbon or nitrogen) circulates through the biotic (living) and the abiotic (non-living) factors of an ecosystem.
  • Elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another through these biogeochemical cycles.
  • Ecosystems have many biogeochemical cycles operating as a part of the system.

• Ocean Floor

  • Microbial life plays a primary role in regulating biogeochemical systems in virtually all of our planet's environments, including some of the most extreme, from frozen environments and acidic lakes, to hydrothermal vents at the bottom of deepest oceans, and some of the most familiar, such as the human small intestine.
  • These microbes play a vital role in biogeochemical cycles.
  • The nitrogen cycle, the phosphorus cycle and the carbon cycle all depend on microorganisms in one way or another.

• Planktonic Food Webs

  • Aside from representing the bottom few levels of a food chain that supports commercially important fisheries, plankton ecosystems play a role in the biogeochemical cycles of many important chemical elements, including the ocean's carbon cycle.

• Microbes and Ecosystem Niches

  • By virtue of their omnipresence, microbes impact the entire biosphere; indeed, microbial metabolic processes (including nitrogen fixation, methane metabolism, and sulfur metabolism) collectively control global biogeochemical cycling.

• Planktonic Communities

  • Aside from representing the bottom few levels of a food chain that supports commercially important fisheries, plankton ecosystems play a role in the biogeochemical cycles of many important chemical elements, including the ocean's carbon cycle.

• Acetyl CoA and the Citric Acid Cycle

  • The citric acid cycle, shown in —also known as the tricarboxylic acid cycle (TCA cycle) or the Krebs cycle—is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate—derived from carbohydrates, fats, and proteins—into carbon dioxide.
  • The NADH generated by the TCA cycle is fed into the oxidative phosphorylation pathway.
  • Components of the TCA cycle were derived from anaerobic bacteria, and the TCA cycle itself may have evolved more than once.
  • Theoretically there are several alternatives to the TCA cycle, however the TCA cycle appears to be the most efficient.
  • If several alternatives independently evolved, they all rapidly converged to the TCA cycle.

• Hyperthermophiles from Submarine Volcanic Habitats

  • Groups that include conspicuous or biogeochemically-important taxa include the sulfur-oxidizing gamma and epsilon proteobacteria, the Aquificaeles, the methanogenic archaea and the neutrophilic iron-oxidizing bacteria.

• The Reverse TCA Cycle

  • The reverse TCA cycle utilizes carbon dioxide and water to form carbon compounds.
  • The citric acid cycle (TCA) or Krebs cycle, is a process utilized by numerous organisms to generate energy via the oxidation of acetate derived from carbohydrates, fats, and proteins into carbon dioxide .
  • However, there are numerous organisms that undergo reverse TCA or reverse Krebs cycles.
  • The chemical reactions that occur are the reverse of what is seen in the TCA cycle .
  • The following is a brief overview of the reverse TCA cycle.

• The Iron Cycle

  • Iron is an important limiting nutrient required for plants and animals; it cycles between living organisms and the geosphere.
  • Iron (Fe) follows a geochemical cycle like many other nutrients.
  • The Terrestrial Iron Cycle: In terrestrial ecosystems, plants first absorb iron through their roots from the soil.
  • The Marine Iron Cycle: The oceanic iron cycle is similar to the terrestrial iron cycle, except that the primary producers that absorb iron are typically phytoplankton or cyanobacteria.
  • Thus far, the results of iron fertilization experiments have been mixed, and there is concern among scientists about the possible consequences of tampering nutrient cycles .