09 Biogeochemical Cycles Free Online FlashCards

What does a biogeochemical cycle describe?

A biogeochemical cycle describes how matter moves among living organisms and nonliving parts of Earth, such as the atmosphere, water, soil, and rocks.

How does matter’s movement through ecosystems differ from energy’s?

Matter is continually recycled through ecosystems. Energy flows through them and is eventually lost as heat.

What is evapotranspiration?

Evapotranspiration is the combined movement of water vapor from evaporation at water surfaces and transpiration by plants.

How does photosynthesis move carbon in the carbon cycle?

Photosynthesis moves carbon from the atmosphere or water into plants and algae.

How does fossil-fuel combustion affect the carbon cycle?

Combustion of coal, oil, and natural gas transfers long-stored carbon to the atmosphere.

What is nitrogen fixation?

Nitrogen fixation converts atmospheric $\mathrm{N_2}$ into biologically available forms, including ammonia or ammonium.

Which processes move sulfur among its reservoirs?

Sulfur cycles through organisms, soil, water, rocks, and the atmosphere. Weathering, decomposition, volcanic activity, and fossil-fuel burning move it among these reservoirs.

What distinguishes the phosphorus cycle’s pathway through ecosystems?

Unlike the water, carbon, and nitrogen cycles, the phosphorus cycle has no major gaseous stage, so its movement through ecosystems is often relatively slow.

How can excess nutrients harm aquatic life?

Excess nutrients can promote algal blooms. When the extra organic matter decomposes, decomposers use oxygen, potentially leaving too little for aquatic life.

What can happen to water after precipitation reaches land?

It may flow over land as runoff, soak into soil and replenish groundwater, or be taken up by organisms.

How do respiration and decomposition return carbon?

Respiration and decomposition return carbon to the atmosphere or water as $\mathrm{CO_2}$.

What happens during ammonification?

Ammonification occurs when decomposers return organic nitrogen from waste or dead organisms to the soil as ammonium.