Use of Illite Clay for In Situ Remediation of ¹³⁷Cs-Contaminated Water Bodies:  Field Demonstration of Reduced Biological Uptake

Abstract

We hypothesized that adding micaceous minerals to 137Cs-contaminated aquatic systems would serve as an effective in situ remediation technique by sequestering the contaminant and reducing its bioavailability. Results from several laboratory studies are presented from which an effective amendment material was chosen for a replicated field study. The field study was conducted over a 2-year period and incorporated 16 3.3-m diameter column-plots (limnocorrals) that were randomly placed in a 137Cs-contaminated pond. The limnocorrals received three rates of amendment treatments to their water surfaces. The amendment material was a commercially available mineral with high sorption (Kd > 9000 L kg(-1)) and low desorption (<20%) characteristics for cesium, even in the presence of high concentrations of the competing cation, NH4+. In the treated limnocorrals, 137Cs concentrations were reduced some 25-30-fold in the water, 4-5-fold in aquatic plants, and 2-3-fold in fish. The addition of the amendment did not adversely affect water chemistry, although increased turbidity and subsequent siltation did alter the aquatic macroinvertebrate insect community. This in situ technology provides a valuable, less-environmentally intrusive alternative to costly ex situ technologies that require the contaminated sediment to be excavated prior to treatment, or excavated and disposed of elsewhere.

Molecular dynamics simulations of cesium adsorption on illite nanoparticles

“…In the Fukushima region, in particular, 137 Cs is the main source of external radiation dose five years after the nuclear disaster of March 2011. The most important process controlling the solubility and mobility of cesium in soils, sediments, and sedimentary rocks is the formation of strong surface complexes with clay minerals [1] and particularly with the micaceous minerals, illite, vermiculite, and mica [28,40,11,63,65]. Cesium adsorption on illite is of particular importance in the geologic storage of radioactive waste, because illite often dominates the mineralogy of finegrained sedimentary rocks considered for use as host formations [94,35,17].…”

Toxicodynamic modeling of 137Cs to estimate white-tailed deer background levels for the Department of Energy's Savannah River Site

“…However, a component that cannot be ignored that will affect the soils ability to retain 137Cs especially in sandy soils is rainfall. During drought years, 137Cs is much more bioavailable in many soil types (Golmakani et al 2008;Goor et al 2003;Heckman and Kamprath 1992;Hinton et al 2006;Leigh and Johnston 1983;Nimis 1996). This is most likely demonstrated in the variability of the data for nonindustrial impacted compartments throughout the SRS.…”

Reduced Plant Uptake of 137Cs Grown in Illite-amended Sediments

“…Additionally, while the actual uptake of 137 Cs varied between the two plant species, the general trends were similar, demonstrating the effectiveness of this treatment among plant species. A field demonstration study research at SRS demonstrated the potential for 137 Cs concentrations to be reduced in the water column, aquatic plants, and fish by the addition of illite (Hinton et al 2006). This remediation strategy could provide a less environmentally destructive and more cost effective alternative to conventional contaminant removal methods (Hinton et al 2006).…”

“…This will be discussed in more detail below. Previous research at SRS evaluated the ability of different clays to sequester 137 Cs and verified that Todd Light Illite is among the most effective (Hinton et al 2006).…”

“…Comparison of other US sites with 137 Cs contamination, such as Oak Ridge, TN and Hanford, WA, provides evidence that sediment composition influences the mobility of 137 Cs within the system, and clay soils more effectively sequester 137 Cs than other types of soils (Sharitz et al 1975;Evans et al 1983;Carlton et al 1992;Guivarch et al 1999;McKinley et al 2001). Since 137 Cs is most strongly sorbed to the clay fraction of soils or sediments, the amount of clay and the type of clay present affects its mobility (Sawhney 1972;Comans and Hockley 1992;Hinton et al 2001;Sanchez et al 2002;Hinton et al 2006).…”