Which statement best describes the sulfur cycle?

Which statement best describes the sulfur cycle?

• A. It describes sulfur movement within the atmosphere only.
• B. It explains how sulfur circulates through the biosphere including SO4 2- in deep ocean sediments, rock, H2S from bogs, SO2 from volcanoes, and H2SO4 from the atmosphere to land.
• C. It is the cycle of sulfur between soil and plants only.
• D. It involves sulfur exclusively as sulfide minerals in rocks.

Answer: (D)

Sulfur moves through air, water, soil, rocks, and living organisms, changing among several chemical forms as it cycles. It appears as sulfate in oceans and minerals, hydrogen sulfide in anaerobic soils and wetlands, sulfur dioxide emitted from volcanoes, and sulfuric acid formed in the atmosphere that returns to land via precipitation. Rocks and minerals release sulfates through weathering, microbes shuttle sulfur between sulfate and sulfide forms, and atmospheric processes transport sulfur around the globe before it is deposited again. This broad circulation—involving the biosphere, hydrosphere, lithosphere, and atmosphere with multiple sulfur forms—best describes the sulfur cycle. The other options are too narrow: focusing only on the atmosphere, only on soil and plants, or portraying sulfur exclusively as sulfide minerals omits many other important reservoirs and forms involved in the cycle.

Sulfur moves through air, water, soil, rocks, and living organisms, changing among several chemical forms as it cycles. It appears as sulfate in oceans and minerals, hydrogen sulfide in anaerobic soils and wetlands, sulfur dioxide emitted from volcanoes, and sulfuric acid formed in the atmosphere that returns to land via precipitation. Rocks and minerals release sulfates through weathering, microbes shuttle sulfur between sulfate and sulfide forms, and atmospheric processes transport sulfur around the globe before it is deposited again. This broad circulation—involving the biosphere, hydrosphere, lithosphere, and atmosphere with multiple sulfur forms—best describes the sulfur cycle. The other options are too narrow: focusing only on the atmosphere, only on soil and plants, or portraying sulfur exclusively as sulfide minerals omits many other important reservoirs and forms involved in the cycle.