Sulfur Cycle
Sulfur is found in every living cell as it is part of the molecules that form amino acids. It is necessary for the formation of collagen, skin, nails and cartilage.
Sulfur is found mostly in rocks. Weathering and erosion of rock release sulfur, turning it into sulfates. Eruptions of volcanos release sulfur from deep down the ground. Burning of fossil fuels also releases sulfur into the air as sulfur dioxide. This gas dissolves in rainwater and becomes sulfuric acid. Plants absorb the sulfated from the soil and convert them into organic forms.
When animal eat the plants, sulfur is moved through the food chain. When the animal and plants die, they decay and release sulfur compounds into the soil. Some are absorbed by plants and some get trapped in sediments or rock formation again.