Which natural process contributes to sulfur levels in the atmosphere?

Volcanic eruptions significantly contribute to sulfur levels in the atmosphere. When a volcano erupts, it releases various gases, including sulfur dioxide (SO2), into the air. This gas can lead to the formation of sulfuric acid in the atmosphere, which plays a role in acid rain and can have broader implications for air quality and climate.

The process of volcanic eruptions introduces vast amounts of naturally occurring sulfur into the environment, emphasizing its role as a natural source of sulfur. Other processes, such as photosynthesis, animal respiration, and plant decay, do not contribute appreciably to atmospheric sulfur levels compared to volcanic activity. These processes are important in their own right but primarily focus on carbon and oxygen cycling rather than sulfur.