Authors

Abstract

: Wetlands have several important roles in the hydrological cycle, includingmaintaining water quality by removing surface and groundwater contaminants. Over time,the wetlands themselves can become contaminated, posing a secondary environmentalthreat. The objective of this study was to calculate the inventory of uranium (U)remaining in a wetland 50 years after the Fuel Fabrication Facility on the Savannah RiverSite located in South Carolina released 43.5 Mg of U into the nearby environment. Over232 700 gamma spectra and their associated global positioning system (GPS) coordinateswere collected and collated into a map of the contaminated land area. Five core sampleswere also collected that contained U concentrations as high as 14 099 mg/kg(background levels are about 2.7 mg/kg U). The contaminated area was 278 000 m²,and it contained 36.2 Mg U, about 83% of the U released. About 80% of the U in thewetland was concentrated in a former beaver pond, a 73 000 m² area (26% of thecontaminated area). This contaminated wetland area was almost 2 km from the source,indicating that it comprised unique hydro-biogeochemical properties for immobilizing the released U. To the best of our knowledge,this is the first data-rich study to quantify the long-term effectiveness of a wetland to immobilize inorganic contaminants. Significantenvironmental changes to the system, such as those associated with hydrology, forest fires, or anthropogenic land use, may alter thecomplex hydro-biogeochemical interactions necessary for the long-term immobilization of the U.