chapter 53 - nutrient cycling

what are the 4 major nutrient cycles?

water, nitrogen, phosphorus, and carbon

major reservoir for water?

oceans

major reservoirs for nitrogen?

atmosphere (N₂)

what organisms perform nitrogen fixation?

diazotrophs (bacteria like rhizobia, frankia)

what human process also fixes nitrogen?

haber-bosch industrial fertilizer production

what is eutrophication?

excess N & P→ algal blooms→ oxygen depletion→ fish death

what causes hypoxia (dead zones)?

bacterial decomposition of algal blooms uses up dissolved oxygen

why is phosphorus cycle local?

no gaseous form of phosphorus

what are prairie strips?

perennial vegetation bands that reduce nitrogen (85%) and phosphorus (90%) runoff

major reservoirs in the carbon cycle?

oceans, soils, atmosphere (small but important)

what is the greenhouse effect?

CO₂, CH₄, and N₂O trap heat radiated from earth

what is “peak phosphorus” ?

the point at which global phosphorus production reaches its maximum, after this, supply declines while demand continues, creating agricultural challenges