nutrient cycle

A nutrient cycle, also known as a biogeochemical cycle, describes the natural pathways by which essential elements circulate through Earth's living and nonliving components. These cycles are crucial for ecosystems to survive, as they ensure the continuous recycling of chemical elements.1

There are two main types of biogeochemical cycles:
* Gaseous cycles: These involve elements that cycle through the atmosphere or oceans, such as nitrogen, oxygen, carbon, and water.1
* Sedimentary cycles: These involve elements that cycle through Earth's crust, like iron, calcium, phosphorus, and sulfur.1

Nutrients are elements and compounds that organisms need for growth. Key elements like hydrogen, oxygen, carbon, nitrogen, phosphorus, and sulfur form the core of living cells. These elements move between inorganic and organic states as they cycle through the atmosphere, lithosphere (soil and crust), hydrosphere (water), and biosphere (living things). For instance, the same atoms of carbon or nitrogen can move between organisms, the atmosphere, soil, and oceans over time.2

Human activities, such as deforestation, burning fossil fuels, and excessive fertilization, can disrupt these natural cycles, leading to environmental issues like increased atmospheric carbon dioxide and nutrient enrichment in aquatic systems (eutrophication).34