Comprehensive Guide to Biogeochemical Cycles: Water, Carbon, Nitrogen, and Phosphorus

Vocabulary flashcards covering the key terms, processes, reservoirs, biological importance, and human impacts of the phosphorus, water, carbon, and nitrogen cycles.

Reservoirs

A place where a material is stored for a period of time.

Sinks

A reservoir that takes in more of a compound than it releases.

Sources

A reservoir that releases more of a compound than it takes in.

Phosphorus Cycle

A biogeochemical cycle that is very slow compared to water, carbon, and nitrogen, and is the only cycle to not involve an atmospheric component.

Phosphorus Reservoirs

Phosphate salts containing phosphate ions, terrestrial rock formations, and ocean bottom sediments.

Phosphate Ions ($PO_4^{3-}$)

An important nutrient incorporated into nucleic acids, ADP, ATP, bones, and teeth.

Eutrophication

An environmental consequence in bodies of water caused by excess phosphates or nitrates ($NO_3^-$) from agricultural fertilizer runoff, animal manure, and sewage discharge.

Water Cycle Reservoirs

Surface water (oceans, rivers, lakes), glaciers, groundwater (aquifers), water vapor atmospheric gas, and living organisms.

Transpiration

The release of water vapor by plants powered by the sun; in rainforests, it serves as the primary source of rainfall.

Carbon Cycle Reservoirs

The ocean (the largest reservoir), calcium carbonate in shells, marine sediments forming limestone, fossil fuels (oil, natural gas, coal), tropical rain forests, tundra (permanently frozen plant matter), the atmosphere, and living organisms.

Nitrogen Reservoirs

The atmosphere, where nitrogen gas ($N_2$) makes up $78\%$ of the air.

Nitrogen Fixation

The process where electrical discharges (lightning) or bacteria and cyanobacteria combine gaseous $N_2$ with hydrogen to produce ammonia ($NH_3$) and/or ammonia ions ($NH_4^+$).

Nitrification

The process where soil bacteria convert ammonia not taken up by plants into nitrate ions ($NO_3^-$) and nitrites, which can be easily absorbed by plant roots.

Assimilation (Nitrogen Cycle)

The process where plants use ammonia or nitrate ions to synthesize proteins, nucleic acids (DNA and RNA), and vitamins, which are subsequently ingested by consumers.

Ammonification

The process occurring upon organism death and decomposition where decomposer bacteria convert organic material into ammonia ($NH_3$) and ammonia ions ($NH_4^+$).

Denitrification

The process in waterlogged soil and lake bottoms where specialized bacteria convert ammonia ($NH_3$) and ammonia ions ($NH_4^+$) back into nitrate ions, and subsequently into nitrogen gas and nitrous oxide gas released to the atmosphere.