1.6 Phosphorus Cycle APES

Why is it a limiting nutrient?

B/c is cycles slowly, plant growth is limited by P availibility in soil/ water (P is needed for DNA, ATP, bone and tooth enamel)

Major natural source

Weathering of ROCKS (wind and rain break down phosphate PO4^-3

Synthetic human sources

Adding fertilizers and detergents/cleaners

Anthropogenic

Anything that was human caused (Negative)

What returns phosphate to soil

animal waste, plant matter, and other biomass being broken down by bacteria/soil decomposers

Sediment

Large amounts of phosphate forming solid bits that fall to the bottom of water, and can be compressed over time into sed. rock

Geological uplift

Tectonic plate collision forcing up rock layers that form mountains (P cycle can start over again with weathering and release phosphate from rock)

Eutrophication

Limiting nutrients, extra input of N and P, excess nutrients, fuels algae. (Algae bloom covers surface of water, blocking sun and killing plants below surface)

What happens when Algae die off?

Bacteria that break down dead algae use up O2 in the water (b/c decomp=aerobic process)

What do lower O2 levels do?

Kills aquatic life, especially fish (Dissolved oxygen)

Positive feedback loop

Less O2→more dead org.→more bacterial decomp.→less O2

What causes eutrophication

fertilizers, runoff, human/animal waste contamination

Example of positive feedback loop

Tundra storing carbon in soil, and when soil unfreezes, carbon is released