Oxidation of groundwater arsenic and iron

The behaviors of dissolved arsenic and iron are significantly decoupled in groundwaters beneath a closed landfill in southern Maine and in laboratory experiments using these groundwaters. At this site naturally-occurring arsenic is mobilized from the glacial sediments under reducing conditions induced and promoted by landfill leachate. Differences in arsenic and iron behavior were seen in laboratory titration experiments which progressively oxidize groundwater from this site and in field data for groundwater composition in the area surrounding this former landfill. The persistence of elevated levels of dissolved arsenic in groundwaters where dissolved iron is relatively low provides direct indication of the difficulty of preventing transport of arsenic from this type of site.