During the water cycle, when rainwater flows over mountain surfaces, which type of biogeochemical cycle does it help mobilize elements such as phosphorus into aquatic ecosystems?

Correct answer: The sedimentary cycle

Correct answer: B, the sedimentary cycle. Phosphorus is mainly stored in rocks, minerals, and sediments rather than having a major atmospheric gaseous phase. Weathering breaks down phosphate-bearing rocks, and rainwater can dissolve or carry the released phosphate particles and ions through runoff into soils, rivers, lakes, and other aquatic ecosystems. Organisms then incorporate phosphorus into biological molecules, and it may later return to sediments. This is why phosphorus is classically associated with a sedimentary biogeochemical cycle. A is too narrow and concerns nitrogen in a different form. C does not identify the relevant classification, and D ignores erosion and runoff. Memory cue: phosphorus comes mainly from rocks, so remember “P for phosphate in particles and sediments.”