AICE Environmental Management Paper 2 Practice Exam

Phosphorus moves through rocks, soils, water, and living organisms rather than cycling through the atmosphere, so its cycle is sedimentary and very slow. Phosphate minerals in rocks weather and release phosphates into soils and rivers. Plants take up these phosphates, and phosphorus then moves through food webs as organisms eat and decompose. Waste and detritus return phosphates to soils and waters, where they can settle and become part of sediments and, over long timescales, reform rocks. Because there isn’t a significant gaseous phase for phosphorus under Earth conditions, there’s no large atmospheric pool to drive rapid transfer, making this the slowest of the biogeochemical cycles. Phosphorus is essential for life, in molecules like ATP and DNA, which is why this tightly linked, sedimentary pathway matters for ecosystems.