APES Notes 1.6 - Phosphorus Cycle

Overview and Reservoirs00:00:00

The phosphorus cycle is a slow process involving the movement of phosphorus between rocks, sediments, and living organisms. Unlike carbon and nitrogen, phosphorus lacks a gas phase, which is why it cycles much more slowly.

The Role of Weathering00:02:45

Weathering occurs when wind and rain break down phosphorus-containing rocks, releasing phosphate into the soil and water. Phosphorus is critical for all living things as it is a component of ATP, DNA, and skeletal structures.

Human Impact and Assimilation00:03:41

Humans influence the cycle by mining rocks for fertilizers and detergents. These phosphates can wash into water bodies, causing an influx of nutrients. Plants absorb phosphorus through roots, which then moves through the food chain and returns to the soil via decomposition.

Sedimentation and Geological Uplift00:05:19

Phosphorus settles at the bottom of bodies of water through sedimentation, eventually compressing into sedimentary rock. Tectonic activity then performs geological uplift, bringing this rock to the surface to restart the weathering process.

Eutrophication and Dead Zones00:06:26

Excess phosphorus and nitrogen inputs lead to eutrophication, causing algal blooms. When algae die, decomposers use up the water's oxygen, creating a positive feedback loop that results in 'dead zones' where aquatic life cannot survive.