Steps of the Phosphorus Cycle

Phosphorus

• Is a limiting factor in soils and streams– Is an important component of DNA, RNA, and

ATP – the molecule cells use to get energy– Organisms can’t grow/function without

Phosphorus

• When you have too much = pond scum• Basically a one-way street (because of time

scales and element properties, etc.)• Phosphorus is NEVER in the atmosphere

Sulfur Cycle

• The Sulfur Cycle contributes to acid rain

Reservoir

• Reservoir: pool of stock of material• source (emits), sink (takes in), can be both• Flux: rate of transfer between reservoirs per unit time• Average residence time: time taken for material to cycle

through system• average residence time = total size of reservoir/rate

of flow• short residence time: small reservoirs, high transfer

rates, easy to impact• long residence time: large reservoirs, slow transfer,

slower to change