Microbial processes influencing the transport, fate and groundwater impacts of fuel ethanol releases

► Ethanol could hinder BTEX attenuation by various biogeochemical mechanisms. ► O2 depletion, enzyme repression and metabolic flux dilution elongate BTEX plumes. ► Elongation is site-specific and is offset by fortuitous growth of BTEX degraders. ► Ethanol migrates through the capillary fringe, a zone of high microbial activity. ► Ethanol-derived CH4 could pose an explosion risk and enhance BTEX vapor intrusion.