Sulfur Cycle

Sedimentary and Gaseous

• Sedimentary cycle– Weathering of rock and leaching of its minerals,

transport, deposition and burial.• Gaseous Cycle– A biogeochemical cycle with the main reservoir or

pool of nutrients in the atmosphere and ocean

Sulfur enters the biosphere through

• Natural Activity

Weathering of rocks and decomposition

Carried through terrestrial environments in salt

solution.

PlantsConsumers

Sulfur enters the atmosphere through

• Natural Activity

Volcanic eruptions, gases released by decomposition

• Human Activity

Burning of fossil fuels, acidic drainage from mines

Enters atmosphere as H2S and reacts with oxygen to

form SO2

SO2 is soluble in H2O Acid rain (H2SO4)

plantsconsumers

Death of consumers Sulfur to the atmosphere

soilPonds, lakes, seas and oceans

Different kinds of bacteria process this sulfur

Non-photosynthetic photosynthetic

Colorless sulfur bacteria

Purple bacteria

Green bacteria

Sulfur

Iron

Ferrous sulfide (FeS2)

Sulfur from the oceans

Released in the atmosphere as Dimethyl sulfide ((CH3)2S )

Go back to the atmosphere by bacteria fixation, or sea

sprays