Variability of CO₂, CH₄, and O₂ Concentration in the Vicinity of a Closed Mining Shaft in the Light of Extreme Weather Events—Numerical Simulations

With climate change, more intense weather phenomena can be expected, including pressure drops related to the arrival of an atmospheric front. Such drops of pressure are the main reason for gas emissions from closed mines to the surface, and a closed, empty mine shaft is the most likely route of this emission. Among the gases emitted, the most important are carbon dioxide and methane, creating a twofold problem—greenhouse gas emissions and gas hazards. The work presented in this paper simulated the spread of the mentioned gases near such an abandoned shaft for four variants: model validation, the most dangerous situations found during measurements with or without wind, and a forecast variant for a possible future pressure drop. It was found that a momentary CO₂ emission of 0.69 m³/s and a momentary CH₄ emission of 0.29 m³/s are possible, which for one hour of the appropriate drop would give hypothetically 2484 m³ CO₂ and 1044 m³ CH₄. In terms of gas hazards, the area that should be monitored and protected may exceed 25 m from a closed shaft in the absence of wind influence. The wind spreads the emitted gases to distances exceeding 50 m but dilutes them significantly.