DGT as a useful monitoring tool for radionuclides and trace metals in environments impacted by uranium mining: Case study of the Sagnes wetland in France.
The Diffusive Gradients in Thin films (DGT) technique was used to analyse U, (226)Ra and other trace metals in stream water and soil porewater in a wetland in France impacted by uranium mining. High resolution profiles of metals in soil porewater obtained by DGT could be measured for the first time up to a depth of 75 cm by the construction of a novel DGT holder. In stream water, the DGT technique was compared to speciation carried out by filtration (0.45 μm) and ultrafiltration (UF) (500 kDa/100 kDa/10 kDa) and DGT porewater profiles were compared with piezometer data obtained in a parallel study. An increase in the trace concentrations of dissolved (0.45 μm) and particulate U, (226)Ra, and elements such as Al, Fe, Mn and Ba was observed in the stream water as it passes through the bog as a results of mobilization from the wetland. The porewater results indicate DGT labile metals species to be present in porewater and mobilization of uranium and other elements linked to the presence of enriched clays. In stream water, colloids and particles govern the behavior of U, Al and Fe, whereas Mn, Ba and Ra are essentially transported as truly dissolved metal species with DGT labile concentrations accounting for 100% of the dissolved fraction. The combined approaches of DGT and UF allow us to obtain a better understanding on the biogeochemical processes involved in the retention and mobility of U and (226)Ra in the wetland.
Vrije Universiteit Brussel VUB, Department Analytical, Environmental and Geochemistry (AMGC), Brussels, Belgium. Electronic address: mleermak@vub.ac.be.
Martine
M
Leermakers
AREVA Mines - R&D Dpt., Tour AREVA,1 Place Jean Millier, 92084 Paris La Défense, France.
Vannapha
V
Phrommavanh
Vrije Universiteit Brussel VUB, Department Analytical, Environmental and Geochemistry (AMGC), Brussels, Belgium.
Jagoda
J
Drozdzak
Vrije Universiteit Brussel VUB, Department Analytical, Environmental and Geochemistry (AMGC), Brussels, Belgium.
Yue
Y
Gao
AREVA Mines - R&D Dpt., Tour AREVA,1 Place Jean Millier, 92084 Paris La Défense, France.
Jérémy
J
Nos
AREVA Mines - R&D Dpt., Tour AREVA,1 Place Jean Millier, 92084 Paris La Défense, France.
Michael
M
Descostes
D003102:Colloids / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D005602:France; D008906:Mining; D011868:Radioisotopes / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D014131:Trace Elements / Q000737:chemistry*; D014462:Ultrafiltration; D014501:Uranium / Q000737:chemistry*; D014867:Water / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000737:chemistry; D014875:Water Pollutants, Radioactive / Q000737:chemistry; D053833:Wetlands
D003102:Colloids; D011868:Radioisotopes; D012987:Soil; D014131:Trace Elements; D014874:Water Pollutants, Chemical; D014875:Water Pollutants, Radioactive; D014867:Water; D014501:Uranium
DGT; Diffusive gradient in thin films; Radium; Ultrafiltration; Uranium; Uranium mines; Wetland