biogeochemical cycles

Vocabulary flashcards for key concepts in environmental systems, matter, energy, and biogeochemical cycles.

Biogeochemical Cycle

The movement of matter (nutrients) through the biotic (living) and abiotic (non-living) components of an ecosystem. These cycles are critical for sustaining life and often involve biological, geological, and chemical processes.

Nutrient Cycling

The overarching process describing the continuous movement and reuse of essential chemical elements (like Carbon, Nitrogen, Phosphorus) between living organisms and the physical environment, ensuring their availability for biological processes within an ecosystem.

Hydrologic Cycle (Water Cycle)

The continuous movement of water on, above, and below the surface of the Earth. Key processes include: 1. Evaporation (water vaporizing from surfaces). 2. Transpiration (water released by plants). 3. Condensation (vapor forming clouds). 4. Precipitation (water returning to Earth as rain, snow). 5. Runoff (water flowing over land). 6. Infiltration (water soaking into the ground).

Carbon Cycle

The flow of carbon through the atmosphere, oceans, terrestrial biosphere, and geological formations. Major reservoirs include: 1. Atmosphere (CO\text{2}). 2. Oceans (dissolved CO\text{2}, carbonates). 3. Land (biomass, soil organic matter). 4. Rocks (limestone, fossil fuels). Processes include photosynthesis, respiration, decomposition, combustion, and ocean absorption/release.

Nitrogen Cycle

The process through which nitrogen is converted between its various chemical forms, circulating between the atmosphere, terrestrial, and marine ecosystems. Key stages: 1. Nitrogen Fixation (atmospheric N\text{2} to ammonia/ammonium by bacteria). 2. Nitrification (ammonia to nitrites then nitrates). 3. Assimilation (plants absorb nitrates/ammonia). 4. Ammonification (decomposers convert organic nitrogen to ammonia). 5. Denitrification (nitrates back to N\text{2} gas).

Phosphorus Cycle

The movement of phosphorus through the lithosphere, hydrosphere, and biosphere. Unlike carbon and nitrogen, the phosphorus cycle does not have a significant atmospheric gaseous phase. It primarily involves: 1. Weathering of rocks (releasing phosphate). 2. Absorption by plants from soil. 3. Transfer through food webs. 4. Decomposition (returning phosphate to soil/water). 5. Sedimentation (forming new rocks over geological time).

Sulfur Cycle

The cycle through which sulfur moves between rocks, waterways, and living systems. Sulfur is found in atmospheric gases (e.g., SO\text{2}, H\text{2}S), dissolved in water (sulfates), and incorporated into organic matter. Processes include: 1. Weathering of sulfur-containing rocks. 2. Volcanic eruptions. 3. Bacterial activity (converting sulfur forms). 4. Industrial emissions (contributing to acid rain). 5. Plant uptake.