What is the common source of hydrogen sulphide in an underground environment?

The common source of hydrogen sulphide in an underground environment is primarily seam gas from coal deposits. Hydrogen sulphide can form during the process of organic matter decomposition, particularly in anaerobic conditions which are often present in coal seams. The coal itself contains sulfur compounds, and as it undergoes chemical reactions, it can release hydrogen sulphide gas.

This gas poses a significant risk in mining and drilling operations, and its presence can indicate the potential for hazardous conditions. Understanding the origins of hydrogen sulphide in geological environments helps industry professionals develop better safety measures and protocols to manage exposure. The other options, while they may have some relevance in discussions of gas sources and environmental impact, do not provide the direct and significant contribution to hydrogen sulphide formation as seam gas from coal deposits does.