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

Abstract

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.

Biogeochemistry of uranium in the soil-plant and water-plant systems in an old uranium mine

“…The biogeochemical fate of uranium in polluted sites has been studied considering several aspects, such as the effect of microbial activity (e.g., Beazley et al, 2011;Hu et al, 2016), the plant-soil interaction (e.g., Tandy et al, 2013), the speciation, retention, mobility and bioavailability phenomena (e.g., Crawford and Liber, 2015;Du et al, 2016;Leermakers et al, 2016), the distribution in plants at the cellular level (e.g., Nie et al, 2015), the toxicity and biochemical responses in plants (e.g., Alves et al, 2009;Hogan et al, 2010;Horemans et al, 2016;Srivastava et al, 2010), the distribution in environmental compartments (e.g., Baumann et al, 2014;Kubrová et al, 2014;Pereira and Neves, 2012;Roivainen et al, 2011), the toxicity risk to biota, including humans (Caetano et al, 2014;Lottermoser, 2011;Pereira et al, 2014;Sheppard et al, 2005), and the prospects for U accumulation potential plant (e.g., Jha et al, 2016;Li et al, 2011;Pratas et al, 2014;Ramaswami et al, 2001).…”

Assessing fate and bioavailability of trace elements in soils after digestate application

“…Furthermore, its accumulation capability allows the detection of very low concentrations of labile TE. Finally, DGT can be also used to obtain a depth profile or TE repartition in soils, with an even higher resolution than piezometric sampling (Leermakers et al, 2016;Luo et al, 2013). Such profiles may be helpful to understand the mechanisms of TE release and allow the detection of TE microniches, corresponding to localized highly concentrated mobile TEs, which is not possible with conventional techniques.…”

Diffusive gradients in thin films: devices, materials and applications

“…Chelex-100 resin is the most widely used solid binding adsorbent and has been applied for the measurement of trace metals in sediments, soils and waters (Divis et al 2007;Song et al 2018a;Zhang et al 1998b). The most notable advantage of Chelex-100 resin is that it can determine a large number of metals, to date, the Chelex-100 is typically used to measure cationic metals with DGT, including Fe, Mn, Cd, Co, Cu, Ni, Pb, Zn and Al (Garmo et al 2003;Leermakers et al 2016;Song et al 2018b;Turner et al 2012;Wu et al 2011). Other available materials have also been reported for the determination of metals, such as adsorbent suspended particulate reagent-iminodiacetate (SPR-IDA) and activated carbon (Davison et al 1997;Lucas et al 2012Lucas et al , 2014.…”