Characterization and radionuclide sorption of suspended particulate matters in freshwater according to their settling kinetics

Abstract

Abstract. In freshwater, radionuclide transfers depend both on exchanges between liquid and solid phases and on mass transfers between suspended and bottom sediment. Whereas the former ones depend on chemical processes (sorption/desorption, complexation…), the latter ones are regulated by hydrological and sedimentary considerations (dispersion, erosion, deposit…) closely related to the interactions between flow, suspended matter and bed sediment. Previous studies highlight the need to consider the matter heterogeneity and its specific sediment dynamics to correctly report the in homogeneity of fluxes in time and in space. These considerations lead us to develop an experimental method to distinguish the different particle groups present in natural water, mainly according to their settling kinetics. In this context, this paper presents the experimental protocol TALISMEN to characterize a natural bulk suspension according to its main settling kinetics groups. In a first step, this identification is achieved by the use of a settling tank that allows the monitoring of the suspended solid concentrations at various depths, combined to a settling model applying a multi-class approach. In a second step, the particle groups are isolated and characterized. The sorption property of each group toward 137 Cs is determined by estimation of its distribution coefficients (k d ) and sorption kinetics.

Solid/liquid ratios of trace elements and radionuclides during a Nuclear Power Plant liquid discharge in the Seine River: Field measurements vs geochemical modeling

“…The distribution (or partitioning) coefficient (Kd) between soluble and particulate phases is one of the most important parameters used in estimating the mobility of trace elements or radionuclides (TE or RN) in fresh, estuarine and marine waters. Partition coefficients help to assess health and environmental risks because they allow quantifying pathways of environmental transport, spatial and temporal distributions, mobility and bioavailability of trace element and radionuclides (Sibley et al, 1986;Benes et al, 1992Benes et al, , 1994; Ciffroy et al, 2001;Brach-Papa et al, 2005). (Ciffroy et al, 2000(Ciffroy et al, , 2009.…”

A dynamic box model to predict the radionuclide behaviour in rivers for medium and long-term periods

“…Its formulation is given by [12] , the erosion rate. These parameters can be theoretically computed or experimentally measured from experimental devices [7][8][9][10][11][12].…”

“…Because it is well known now that radionuclide speciation is depending on granulometry and the nature of matters [5][6], the model can take into account several matter classes identified and classified according to their settling kinetics [7]. In the bottom sediment, three main layers are classically considered to compute radionuclide transfers in rivers [8]: an interface, an active layer and a passive layer.…”