This session seeks contributions that describe subsurface arsenic contamination cases (with a focus on mobilization mechanisms) and that report recent advances in subsurface contamination issues from alternative fuels. The recent U.S. EPA rule, which lowered the maximum arsenic contaminant limit in public water facilities from 50 to 10 ppb (in par with WHO guidelines), has led to an immediate increase in water quality violations. It is generally recognized that host rock and aqueous concentrations of arsenic are not strongly correlated and that elevated dissolved arsenic concentrations require some mobilization mechanism. Arsenic mobilization mechanisms include reductive dissolution of iron oxides and iron oxide sorption destabilization. Other processes such as evaporation could also play a role. This session also focuses on recent advances in all aspects of subsurface contamination from alternative fuels, including alcohols and blends of 85% or more of alcohols with gasoline; coal-derived liquid fuels; natural gas and liquid fuels domestically produced from natural gas; hydrogen; biodiesel; and fuels derived from biological materials.