Nutrient Cycles

Introduction to Nutrient Cycles

Nutrient cycles are the processes that move essential elements and compounds through ecosystems.
Biogeochemical cycles are the term for nutrient cycles that involve both living (biotic) and non-living (abiotic) components of ecosystems.

There are several different types of nutrient cycles, but three of the most significant are the carbon cycle, the nitrogen cycle, and the water cycle.
These cycles ensure that essential elements and compounds are continually available to organisms.

The carbon cycle describes how carbon moves through an ecosystem.
Photosynthesis by plants and algae takes carbon dioxide (CO2) from the atmosphere and uses it to produce glucose, which is then used to provide energy for the plant or alga.
Animals obtain carbon by eating plants or other animals. Carbon is returned to the atmosphere as CO2 when animals respire.
Decomposers also play a role in the carbon cycle. When organisms die, decomposers break down their bodies and release carbon back into the environment.

The nitrogen cycle explains how nitrogen moves through ecosystems.
Nitrogen in the atmosphere is fixed by bacteria into a form that plants can use, in a process called nitrogen fixation.
Animals then get the nitrogen they need by consuming plants or other animals.
Like the carbon cycle, the nitrogen cycle also involves decomposers breaking down dead organisms and returning nitrogen to the soil.

The water cycle describes the movement of water within the Earth’s hydrosphere.
It includes the processes of evaporation, transpiration, condensation, and precipitation.
The cycle begins when the sun’s heat causes water to evaporate from the Earth’s surface (land and bodies of water) and from plants (transpiration).
Water vapour collects in the atmosphere, cools and condenses to form clouds.
This water returns to the Earth’s surface as rain, snow, or other forms of precipitation.

Human activities have a significant impact on all of these cycles.
For example, burning fossil fuels increases the amount of carbon in the atmosphere, contributing to climate change.
Use of artificial fertilisers can disrupt the nitrogen cycle, leading to environmental problems such as eutrophication.
Overuse and pollution of water supplies can disrupt the water cycle.

These cycles are essential for maintaining life on Earth.
They ensure that critical elements and molecules are continuously renewed and remain available to sustain ecosystems.
Understanding nutrient cycles can help us make decisions that lead to a more sustainable interaction with our planet.