Introduction to the Living World — Biogeochemical Cycles

Vocabulary flashcards covering key terms related to biogeochemical cycles and the hydrologic, carbon, nitrogen, phosphorus, and sulfur cycles.

Microbes

Microorganisms (bacteria, single-celled protists, and fungi) that recycle nutrients; can be beneficial or harmful to health and ecosystems.

Phytoplankton

Photosynthesizing microorganisms that produce much of the Earth's atmospheric oxygen.

CHONPS

The six major elements—carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur—that make up the majority of biomass.

Biogeochemical cycles

The continuous cycling of major nutrients through living organisms and the physical environment (carbon, hydrologic, nitrogen, phosphorus, sulfur cycles).

Reservoirs/Sinks

Locations where nutrients accumulate or are stored during their cycle.

Hydrologic cycle

Water cycle; movement of water through evaporation, precipitation, transpiration, and runoff, driven by the sun.

Evaporation

Process by which liquid water becomes water vapor from bodies of water.

Transpiration

Water taken up by plant roots is released as water vapor from leaves via stomata.

Stomata

Openings in leaf surfaces that regulate gas exchange and water loss.

Precipitation

Water returned to Earth's surface as rain, snow, etc., which can become surface runoff or infiltrate soil.

Surface runoff

Water that flows over the land into rivers and lakes, with some infiltrating to become groundwater.

Aquifers

Porous layers of soil/rock that store groundwater.

Groundwater

Water stored underground in soil or rock, part of the hydrologic cycle.

Carbon cycle

Movement of carbon among atmosphere, organisms, oceans, and sediments; includes assimilation, respiration, sequestration, and storage.

Carbon dioxide (CO2)

Greenhouse gas involved in the carbon cycle; produced by respiration and burning, absorbed by photosynthesis.

Carbon sequestration

Removal and storage of CO2 from the atmosphere in sinks like oceans, rocks, and biomass.

Fossil fuels

Stored carbon from ancient organisms; burning them releases CO2 into the atmosphere.

Primary producers

Autotrophs (plants, algae) that fix carbon via photosynthesis to form glucose, cellulose, and starch.

Assimilation

Uptake of inorganic carbon (CO2) and inorganic nitrogen by producers to form organic compounds.

Oceanic carbon reservoir

Major carbon reservoir in the oceans, including dissolved CO2, bicarbonate, carbonate, and carbon stored in sediments.

Nitrogen cycle

Movement of nitrogen through the atmosphere, soil, water, and living organisms; includes fixation, assimilation, ammonification, nitrification, denitrification.

Nitrogen fixation

Conversion of N2 to ammonia/ammonium (NH3/NH4+) by bacteria in soil, on legume roots (Rhizobium), and cyanobacteria in water."

Ammonification

Decomposers convert organic matter into ammonia and ammonium (NH3/NH4+).

Nitrification

Bacteria convert ammonia/ammonium to nitrite (NO2-) and then nitrate (NO3-).

Denitrification

Bacteria convert nitrate to nitrogen gas (N2) and nitrous oxide (N2O) in anaerobic conditions.

Ammonium (NH4+)

Inorganic form of nitrogen produced during ammonification and used by plants.

Nitrates (NO3-)

Inorganic nitrogen that plants take up after nitrification.

Nitrogen gas (N2)

Diatomic nitrogen making up about 78% of the atmosphere; largely unavailable to most organisms without fixation.

Nitrous oxide (N2O)

Greenhouse gas produced during denitrification and other processes.

Eutrophication

Over-enrichment of nutrients (N or P) in water leading to algal blooms and oxygen depletion.

Phosphorus cycle

Movement of phosphorus through ecosystems; no atmospheric phase; largest reservoirs in oceanic sediments and rocks; essential for DNA, ATP, and phospholipids; a limiting nutrient in freshwater.

Phosphate (PO4^3-)

Biologically usable form of phosphorus taken up by producers; cycles through food web.

Limiting nutrient

Nutrient that limits primary productivity in a given ecosystem (often phosphorus in freshwater).

Phosphate role in biomolecules

Phosphates are components of DNA, ATP, phospholipid bilayer, and bones/teeth.

Phosphate rock formation

New phosphate-containing rock forms at the bottom of aquatic systems via sedimentation of phosphates.

Detergent phosphate ban

Phosphates were restricted in laundry detergents in parts of North America due to eutrophication concerns.

Sulfur cycle

Movement of sulfur through the atmosphere, hydrosphere, and lithosphere; major reservoirs in oceanic sediments and rocks; involved in various gases and compounds.

Sulfur dioxide (SO2)

Gas released from volcanic activity and burning of fossil fuels; forms sulfuric acid in the atmosphere.

Hydrogen sulfide (H2S)

Sulfur-containing gas produced by anaerobic bacteria.

Dimethyl sulfide (DMS)

Volatile sulfur compound released by marine algae; can affect cloud formation.

Ammonium sulfate

A sulfate salt formed in the atmosphere and precipitation processes.

Sulfuric acid (H2SO4)

Strong acid formed from SO2 in the atmosphere; a major component of acid rain.

Acid deposition

Acid rain and related deposition caused by sulfur and nitrogen emissions.