Inferences About Radionuclide Mobility in Soils Based on the Solid/Liquid Partition Coefficients and Soil Properties

Abstract

To assist transport modeling in assessments of the radiological impact of a geological repository for radioactive wastes, the mobility of various elements was studied in arable and wetland soils in the Forsmark region, Sweden. Pore water and total element contents were determined for five types of unconsolidated deposits (regolith), spanning a wide range of soil properties with respect to pH and organic matter content. Two soil depths were sampled to capture element mobility in regolith layers affected and unaffected by soil-forming processes. The solid/liquid partition coefficients (Kd values) for most elements varied significantly among regolith types. For most elements, the observed variations in Kd values could be explained by variations in soil properties. For many elements, mobility increased with decreasing soil pH. The results provide a significant addition of data on radionuclide retention in soils, taking account of soil properties and processes.Electronic supplementary materialThe online version of this article (doi:10.1007/s13280-013-0408-4) contains supplementary material, which is available to authorized users.

Conceptual and Numerical Modeling of Radionuclide Transport and Retention in Near-Surface Systems

“…With the exception of Se, the computed K d values in the till system are one or several orders of magnitude lower than the measured K d in Forsmark till soils (see Sheppard et al 2011 and Sohlenius et al 2013 for methodology and results on site-specific K d ). Computed K d values of Ni and Cs in the clay system are in the range of those reported by Engdahl et al (2008) for Forsmark lake sediments, whereas those for Th and Sr are one order of magnitude lower and those for U two orders of magnitude lower.…”

“…In these and other applications involving contaminant transport by groundwater, solid/liquid distribution coefficients ( K d ) are widely used to describe the retention of contaminants, i.e., sorption and other processes retarding their migration (Sohlenius et al 2013). The application of K d -based models relies on assumptions of linearity and equilibrium of the processes involved.…”

Humans and Ecosystems Over the Coming Millennia: Overview of a Biosphere Assessment of Radioactive Waste Disposal in Sweden

“…Thus, PDFs based on these studies can have long tails reflecting the low number of observations and variations due to the use of data from various sites obtained by different methods. In contrast, for many elements, the site studies in the SKB program (Lindborg 2006) have produced a limited range of CR and K D values using consistent methods, as shown by Sohlenius et al (2013). …”

“…These different soil properties affect the sorption ( K D ) of radionuclides in different soils. From the studies of K D of soils and soil depths by Sohlenius et al (2013) and Nordén et al (2010), radionuclide accumulation and mobility can be rescaled within the future landscape mosaic. This rescaling of measured retention factors is further supported by mechanistic understanding implemented in reactive-transport models by Piqué et al (2013).…”

Natural radionuclides in plants, soils and sediments affected by U-rich coal mining activities in Brazil

“…An understanding of the mobility of natural radionuclides in soils and their TFs to different plants requires knowing their interactions with soils (Shtangeeva, 2010). The uptake of trace elements by biota can be affected by the electrical conductivity (EC), cation exchange capacity (CEC), total organic carbon (TOC), nutrients, mineralogy and climate, in addition to (bio)chemical processes such as complexation, precipitation and redox reactions (Sohlenius et al, 2013;Gupta et al, 2014;Zhao et al, 2016). However, in about 50% of the investigations focusing on the TF, these characteristics were not considered (Vandenhove et al, 2009), which limits our understanding on the metal uptake by the biota.…”