Midterm: Biogeochemical cycles

Biogeochemical cycle

is the continual recycling of nutrients through the air, water, rock, soil, and living organisms; all nutrients are essential to life, and no new molecules are created.

Groundwater

water that sinks into the soil and is stored in aquifers.

Aquifer

a groundwater storage area.

Carbon cycle

the process by which carbon enters the biosphere during photosynthesis and returns to the atmosphere through cellular respiration.

Photosynthesis

the process in which plants use carbon dioxide and water to produce glucose, oxygen, and water.

Cellular respiration

the process in which glucose and oxygen are used to produce carbon dioxide, water, and energy.

Phosphorus cycle

the movement of phosphorus through rocks, soil, water, and living organisms, influenced by human activities such as mining, deforestation, and runoff.

Eutrophication

excess phosphorus and nitrogen in aquatic systems leading to algal blooms, oxygen depletion, and death of aquatic organisms.

Sulfur cycle

the movement of sulfur through the atmosphere, hydrosphere, lithosphere, and biosphere, influenced by volcanic activity, industries, and fossil fuel burning.

Nitrogen cycle

the process through which nitrogen circulates between the atmosphere, soil, and living organisms via fixation, nitrification, assimilation, ammonification, and denitrification.

Nitrogen fixation

bacteria in the soil convert N2 into NH3 so that plants can use it.

Nitrification

bacteria convert NH3 into nitrite (NO2-) and nitrate (NO3-).

Assimilation

plants absorb ammonia and nitrates; animals obtain nitrogen by eating plants.

Ammonification

decomposer bacteria convert organic waste into ammonia.

Denitrification

bacteria convert ammonia, nitrites, and nitrates into N2, which is released into the atmosphere.