Delineating landfill leachate discharge to an arsenic contaminated waterway.
Discharge of contaminated ground water may serve as a primary and on-going source of contamination to surface water. A field investigation was conducted at a Superfund site in Massachusetts, USA to define the locus of contaminant flux and support source identification for arsenic contamination in a pond abutting a closed landfill. Subsurface hydrology and ground-water chemistry were evaluated in the aquifer between the landfill and the pond during the period 2005-2009 employing a network of wells to delineate the spatial and temporal variability in subsurface conditions. These observations were compared with concurrent measures of ground-water seepage and surface water chemistry within a shallow cove that had a historical visual record of hydrous ferric oxide precipitation along with elevated arsenic concentrations in shallow sediments. Barium, presumably derived from materials disposed in the landfill, served as an indicator of leachate-impacted ground water discharging into the cove. Evaluation of the spatial distributions of seepage flux and the concentrations of barium, calcium, and ammonium-nitrogen indicated that the identified plume primarily discharged into the central portion of the cove. Comparison of the spatial distribution of chemical signatures at depth within the water column demonstrated that direct discharge of leachate-impacted ground water was the source of highest arsenic concentrations observed within the cove. These observations demonstrate that restoration of the impacted surface water body will necessitate control of leachate-impacted ground water that continues to discharge into the cove.
National Risk Management Research Laboratory, US Environmental Protection Agency, Office of Research and Development, 26 W Martin Luther King Dr., Cincinnati, OH 45268, USA. ford.robert@epa.gov
Robert G
RG
Ford
Steven D
SD
Acree
Bob K
BK
Lien
Kirk G
KG
Scheckel
Todd P
TP
Luxton
Randall R
RR
Ross
Aaron G
AG
Williams
Patrick
P
Clark
D001151:Arsenic / Q000032:analysis*; D001464:Barium / Q000032:analysis; D002118:Calcium / Q000032:analysis; D004784:Environmental Monitoring; D005290:Ferric Compounds / Q000737:chemistry; D005618:Fresh Water / Q000737:chemistry*; D019015:Geologic Sediments / Q000032:analysis; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D012044:Regression Analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
D005290:Ferric Compounds; D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; C000499:ferric oxide; D001464:Barium; D001151:Arsenic; D002118:Calcium