4.3 nutrient cycling

Energy flow in ecosystems

Energy flows through trophic levels as a one-time, one-way stream.

Biogeochemical cycles

Cycles powered by energy flow that recycle matter and nutrients within and between ecosystems.

Matter conservation

Matter cannot be created or destroyed; it can only be transformed and recycled.

Human impact on biogeochemical cycles

Human activities like mining, burning fossil fuels, and deforestation greatly affect the natural cycles.

Water cycle

The cycle that involves the movement of water through bodies of water, the atmosphere, living organisms, and the earth.

Nutrient cycles

Processes through which nutrients pass through organisms and the environment, critical for life and ecosystems.

Limiting nutrient

Nutrients that are scarce and hard to find, affecting the productivity of an ecosystem.

Carbon cycle

The cycle that involves the movement of carbon through biological, geological, chemical, and human processes.

Nitrogen cycle

The cycle through which nitrogen is converted into various chemical forms, essential for building proteins and nucleic acids.

Denitrification

The process by which certain bacteria convert nitrogen gas from the air into ammonia.

Oxygen in nutrient cycles

Oxygen participates in the carbon, nitrogen, and phosphorus cycles by combining and cycling with these elements.

Biological processes in biogeochemical cycles

Activities performed by living organisms, such as eating, breathing, and excreting waste.

Geological processes

Natural events like volcanic eruptions and the formation of rocks that affect biogeochemical cycles.

Chemical processes

Processes including cloud formation, precipitation, and water flow that influence biogeochemical cycles.

Nitrogen as a limiting nutrient

In oceans, nitrogen is often the limiting nutrient affecting ecosystem productivity.

Phosphorus as a limiting nutrient

In freshwater environments, phosphorus often acts as the limiting nutrient.