Fosforcycli

Fosforcycli, commonly referred to in English as the phosphorus cycle, describes the movement of phosphorus through the Earth’s systems, including rocks, soils, water, and living organisms. Unlike many other biogeochemical cycles, phosphorus has no significant atmospheric reservoir; most of its cycling occurs in solid and aqueous phases.

The largest reservoirs of phosphorus are in sedimentary rocks and mineral deposits. Weathering and erosion release phosphate into soils and rivers, from which plants can take up inorganic phosphate. Phosphorus then moves through the food chain as organisms consume plants and each other, and is returned to the soil and water through decomposition and excretion. In aquatic environments, phosphate can precipitate or be incorporated into sediments, where it may remain for long periods before re-entering the cycle via geological processes such as uplift and erosion.

Key chemical forms of phosphorus in the cycle include phosphate ions (such as H2PO4− and HPO4^2−) that plants and microorganisms assimilate. The availability of phosphate often limits primary productivity, particularly in freshwater systems, due to adsorption to soil particles and mineral surfaces.

Human activities have significantly altered fosforcycli. The mining and processing of phosphate rock for fertilizers increase the global supply of phosphate to ecosystems, often accelerating eutrophication in lakes and coastal zones through runoff and wastewater discharges. Phosphorus is also considered a finite resource with environmental and geopolitical implications, highlighting the need for sustainable management of fertilizers, wastewater treatment, and phosphorus recycling.

In scientific research and environmental management, the phosphorus cycle is used to understand nutrient limitation, ecosystem health, and the long-term fate of phosphorus in landscapes and oceans.