Geogenic CO2 emissions from post-mining landscapes: Environmental and public health implications in rapidly urbanizing zones of Jos, North central Nigeria.

Gas emissions from abandoned mine shafts constitute a significant post-mining environmental and public health concern, particularly in regions where legacy mining sites are located within or near residential areas. This study investigated carbon dioxide (CO2) emissions from abandoned and active mine shafts in the Lowkon and Heipang areas of Plateau State, Nigeria, with the aim of evaluating the influence of meteorological and geochemical factors on gas migration and potential environmental implications. Field monitoring was conducted between August and October 2025, during which CO2 concentration, air velocity, temperature, humidity, and atmospheric pressure were measured at shaft collars (0 m) and above ground level (1 m). The collected soil samples were subjected to geochemical, mineralogical, and organic carbon analyses to evaluate lithological controls and potential gas migration pathways. Regression analysis was applied to evaluate the relationship between abiotic parameters and CO2 flux. The results indicate that CO2 emissions are strongly influenced by subsurface geogenic sources, shaft mineralogy, and atmospheric conditions, particularly wind velocity, while temperature and pressure show comparatively weak influence. CO2 flux values reached 7.94 kg m-2 s-1 in Heipang and 4.94 kg m-2 s-1 in Lowkon, reflecting efficient upward gas transport through fractured and permeable mine structures. The persistent nature of CO2 emission and proximity to residential areas indicate potential long-term exposure risks. The findings highlight the need for systematic monitoring, proper closure of abandoned mine shafts, and the implementation of targeted regulatory policies to mitigate post-mining gas hazards in the Jos Plateau region.