What causes hydrogen sulfide gas to form in groundwater?
Decay of organic matter such as vegetation, or chemical reactions with some sulfur-containing minerals in the soil and rock, may naturally create hydrogen sulfide in gas in groundwater. As groundwater moves through soil and rock formations containing minerals of sulfate, some of these minerals dissolve in the water. A unique group of bacteria, called “sulfur bacteria” or “sulfate-reducing bacteria” can change sulfate and other sulfur containing compounds, including natural organic materials, to hydrogen sulfide gas.