The

Sulfu

r Cyc

le

Jacob CardenasAndrew Schreiber

Ruben Trillo

The Sulfur Cycle

Natural Process

• Mineralization of organic sulfur into inorganic forms, such as hydrogen sulfide (H2S), elemental sulfur, as well as sulfide minerals.

• Oxidation od hydrogen sulfide, sulfide, and elemental sulfur (S) to sulfate (SO4-2).

• Reduction of salfate and sulfide.• Incorporation of sulfide into organic

compounds.

Natural Reservoirs

• Reservoirs of sulfur atoms: The largest physical reservoir is the Earth’s crust where sulfur is found in gypsum and pyrite.

• The largest reservoir of biologically useful sulfur is found in the ocean as sulfate anions, dissolved hydrogen sulfide gas, and elemental sulfur.

Natural Reservoirs Continued

• Other reservoirs include:• 1. Freshwater – contains

sulfate, hydrogen sulfide and elemental sulfur.

• 2. Land – contains sulfate• 3. Atmosphere – contains

sulfur oxide, and methane sulfonic acid; volcanic activity releases some hydrogen sulfide into the air

Importance

• Sulfur is important for the functioning of proteins and enzymes in plants and also in animals. The plants absorb sulfur when it is dissolved in water, while the animals consume the plants that have received the sulfur nutrient.

Human Impact• Human activities have a major effect

on the global sulfur cycle. The burning of coal, natural gas, and other fossil fuels has greatly increased the amount of Sulfur in the atmosphere and ocean.

• Sulfur cycle is affected everywhere around the earth because of humans. Acid rain is a well known environmental problem. Acid rain is ultimately associated with large emissions of sulfur dioxide to the atmosphere by human sources, such as oil- and coal-fired power plants, metal smelters, and the burning of fuel oil to heat homes.

Human Impact Continued• Humans also increase the flow of sulfates to the atmosphere.

Coal contains relatively large quantities of sulfur, up to 5 percent, which varies by coal type. When coal is burned without scrubbers, its sulfur is released into the atmosphere. There the sulfur can form aerosol particles that reflect sunlight and affect the heat balance of the planet

• “The Tuslequah Chief Mine in British Columbia, Canada, with ore deposits of copper, lead, zinc, gold, and silver, started production in 1951 and lasted until 1957. The mine and its buildings were abandoned and left to rot, with no pollution abatement for the acid mine drainage runoff coming straight from the mine and flowing into the Tulsequah River, where it severely degrades water quality.”

Human Impact Image

Human Activities

• Sulfate is released into the air by the burning of coal.

• Sulfate comes down as dry or wet decomposition.

• In the soil, the plants take in the sulfate.• When it comes into the water, the sulfate goes

into the sediment in the water. • This action also effects the microorganisms in

the soil.

Human Activities Continued