THE PHOSPHORUS CYCLE: ESSENTIAL NUTRIENT DYNAMICS IN TERRESTRIAL AND AQUATIC ECOSYSTEMS

The phosphorus cycle describes the movement of phosphorus — an essential macronutrient — through the lithosphere, hydrosphere, and biosphere. Unlike other major biogeochemical cycles, the phosphorus cycle does not have a significant gaseous phase, and phosphorus primarily moves through weathering, absorption by organisms, and sedimentation. Phosphorus is critical for cellular functions, including energy transfer (ATP), nucleic acids (DNA/RNA), and membrane structure (phospholipids). Human activities, particularly agriculture and fertilizer application, have significantly altered phosphorus flows, contributing to freshwater and coastal eutrophication. This article reviews the mechanisms of the phosphorus cycle, its ecological significance, and the environmental consequences of anthropogenic perturbations.