Deutsch: Schwefel / Español: Azufre / Português: Enxofre / Français: Soufre / Italiano: Zolfo
Sulfur or sulphur (see spelling differences) is a chemical element with symbol S and atomic number 16. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow crystalline solid when at room temperature.

In the context of the environment, sulfur is a chemical element that can have both natural and human-caused sources. Sulfur can have significant impacts on the environment, affecting air and water quality, and the health of ecosystems and human populations.

Here are some examples of sulfur in the environmental context:

1. Sulfur dioxide (SO₂): Sulfur dioxide is a gas that can be emitted into the atmosphere by natural sources such as volcanic activity or human activities, such as burning fossil fuels. SO₂ can contribute to acid rain, which can have negative impacts on forests, lakes, and other ecosystems, as well as on human health.

2. Hydrogen sulfide (H₂S): Hydrogen sulfide is a gas that can be emitted from natural sources, such as swamps and wetlands, as well as from human activities such as oil and gas drilling. H2S is toxic and can have negative impacts on human health and wildlife.

3. Sulfuric acid (H₂SO₄): Sulfuric acid is a strong acid that can form in the atmosphere when SO₂ reacts with other chemicals. Acid rain caused by sulfuric acid can damage buildings, crops, and natural ecosystems, as well as contributing to respiratory problems in humans and animals.

4. Sulfur-containing compounds in water: Sulfur-containing compounds can be present in natural sources of water, such as wells and springs, as well as in wastewater and other industrial discharges. These compounds can produce a foul odor and taste in water, and high concentrations can be toxic to aquatic life.

5. Sulfur in soil: Sulfur is an essential nutrient for plant growth and is naturally present in soils in various forms. However, human activities such as fertilizer application and land use changes can cause changes in the sulfur content of soils, affecting plant growth and potentially contributing to environmental pollution.

6. Sulfur hexafluoride (SF₆): Sulfur hexafluoride is a highly potent greenhouse gas used in a variety of industrial applications. SF₆ can persist in the atmosphere for thousands of years, contributing to global warming and climate change.

In summary, sulfur can have both natural and human-caused sources and can have significant impacts on the environment, affecting air and water quality, as well as the health of ecosystems and human populations. Monitoring and controlling sulfur emissions and ensuring proper management of sulfur-containing substances is essential for protecting the environment and human health.