Heavy metals across the coal lifecycle covering sources, environmental pathways and global remediation strategies

Coal remains a vital component of global energy production. However, its lifecycle from mining and processing to combustion and waste disposal releases heavy metals (HMs) and metalloids that pose a global threat to environmental integrity and public health. This comprehensive review integrates global research on the sources, concentrations, distribution, and speciation of major toxic HMs (As, Cd, Cr, Hg, Pb) associated with coal extraction and utilization. It emphasizes the geochemical behaviour, mobility, bioavailability, and long-term persistence of these contaminants within ecosystems impacted by mining activities. Particular attention is given to key environmental pathways to HM release, particularly acid mine drainage (AMD) and fly ash dispersion. These pathways play critical role in contaminant migration through soil water systems, subsequently facilitating entry into ecological and human food chains at both regional and global scales. The review further evaluates the broader environmental consequences, including ecosystem degradation, biomagnification, and the spectrum of health risks ranging from neurotoxicity to carcinogenicity. In addition, it critically assesses current and emerging remediation technologies worldwide, including adsorption, membrane-based treatments, bioremediation, and advanced methods such as flash Joule heating, highlighting their potential application across diverse coal dependent economies. Collectively, the findings reinforce the urgent global need for integrated, science-driven management strategies that combine robust policy frameworks with innovative remediation solutions and a progressive shift toward sustainable energy systems to mitigate HMs pollution throughout the coal lifecycle.