Mobilization and Retardation of Uranium DOC Species at Three Mine Piles in Schlema/Alberoda, Saxony, Germany

Abstract

The modeling of geo-chemical processes needs the detailed and comprehensive knowledge of all chemical interactions existing in the flow path of waste dumps, subsoil and aquifer. This includes the adsorption, displacement and transport of heavy metal species of fulvic and humic acids, which represent the main amount of DOC in the liquid/solid system of the flow path. Comparative measurements of DOC concentrations in the input and output flow at the three waste dumps in the district Schlema/Alberoda indicated that DOC is produced and/or supplied within the waste dumps. The speciation of heavy metal compounds of fulvic and humic acids was achieved by means of sequential chromatographic analysis SCA and isoelectric focusing IEF. Between 5% and 20% of uranium exist in the flow path in the form of stable fulvic and humic acid species. Their distribution coefficients are strongly correlated with the pH values of the geo-chemical system.

Enrichment of Uranium in Particulate Matter during Litter Decomposition Affected byGammarus pulexL.

“…Furthermore, increase in DOC resulted in a proportional increase of SAC (Figure b). Therefore, the results in this study may contradict some reports concluding that dissolved humic substances or DOC facilitates mobilization of uranium in aquatic systems . However, Ranville et al show that high DOC concentrations do not induce remobilization of uranium when media had pH values above 7 in the presence of excess carbonates.…”

“…It may also occur as organic complex of humic and fulvic acids as part of dissolved organic carbon (DOC) as well as fixed to colloids. In these forms, uranium is readily transported in flowing water systems , .…”

Distribution of uranium in German bottled and tap water

“…The uranium input is ascribed to agricultural sources (phosphate fertilizers) rather than dumped materials. Franke et al (2000), Bolea et al (2006) and Gottschalch et al (2007) found that chalcophilic elements as well as Ca, Cr and U were enriched in the low-molecular weight fractions of humic substances, corresponding to the molecular weight range of fulvic acid.…”

The role of sediment properties and solution pH in the adsorption of uranium(VI) to freshwater sediments

“…Uranium, in comparison to most cationic metals, has a relatively complex solid-aqueous chemistry, which depends on a number of factors that influence the partitioning of U between the aqueous and solid phases (Ames et al, 1983;Catalano and Brown Jr, 2005;CCME, 2011;Langmuir, 1978;Markich, 2002;US EPA, 1999). Many ligands, such as phosphate, carbonate, and humic and fulvic substances can form complexes that are readily soluble and mobile in aquatic systems (Cheng et al, 2006;Franke et al, 2000;Schaller et al, 2008). However, transport of U can be limited by strong adsorption onto solid phases.…”