Sequential Extractions for the Study of Radiocesium and Radiostrontium Dynamics in Mineral and Organic Soils from Western Europe and Chernobyl Areas

Abstract

To study radiostrontium (RSr) and radiocesium (RCs) aging in soils, three sequential extraction schemes were used on Mediterranean loamy and loam-sandy soils, podsols and peaty podsols from the area near Chernobyl, and peats from Western Europe. Aging was quantified by changes in radionuclide distribution. Two factors were thought to affect radionuclide distribution: time elapsed since contamination and drying−wetting cycles. Changes in radionuclide distribution were of low significance in Mediterranean loamy and loam-sandy soils in the short term, even after drying−wetting cycles. In the short term, podsols and peaty podsols showed a decrease in the RSr exchangeable fraction in the laboratory samples (20−25% decrease), whereas samples taken 6 years after contamination did not show any further decrease. For RCs in podsols and peaty-podsols, the application of drying−wetting cycles for 9 months led to observe a 2−3-fold decrease in the exchangeable fraction, whereas time alone did not lead to any change. No RCs aging was observed in peats with a low or almost negligible content of mineral matter, low base saturation and low interception potential for RCs, even after drying−wetting cycles. Finally, changes in the radionuclide exchangeable fraction over time in these soils corresponded to changes in transfer factors over a similar period.

Evaluation of the possibility to use the plant–microbe interaction to stimulate radioactive 137Cs accumulation by plants in a contaminated farm field in Fukushima, Japan

“…The remaining part can be qualified as an unavailable fraction as it was evidently split between the strongly fixed and the residual fractions. This finding is in accordance with those found previously in many reports (Forsberg and Strandmark 2001;Matsunaga et al 2013;Rigol et al 1999;Tsukada et al 2008), where most of the radiocesium was found to be bound to persistent and residual fractions.…”

Stable strontium accumulation by earthworms: A paradigm for radiostrontium interactions with its cationic analogue, calcium

“…This suggests the possibility that for soils with high strontium levels, earthworm uptake of the cation approaches saturation in a fashion analogous to that convincingly demonstrated for strontium uptake by a freshwater fish species [43]. In the absence of detailed information regarding strontium (and calcium) extractable fractions in the field soils (see Rigol et al [42] for methods), and mindful that the physiology and molecular biology of calcium transport in earthworms is poorly known, the present worm data must not be overinterpreted. It is evident, however, that whereas strontium may, to some extent, mimic calcium, the overall accumulation patterns of the two elements differ, and that these patterns reflect the ability of worms to regulate tissue calcium, but not strontium, burdens.…”

“…A number of authors [40][41][42] have shown that organic matter content and cation-exchange capacity influences strontium equilibria and bioavailability, particularly to plants. The CF values integrated in our study across eight sites and four earthworm species encompassed the range reported by Krivolutsky et al [24] but spanned from 0.10 to 1.42, with the highest values being recorded in soils with low strontium concentrations, and vice versa.…”

Temporal variations of accumulated cesium in natural soils after an uncharacteristic external exposure

“…The effects of elapsed time following the contamination of soils with 137 Cs were observed during our study of the 133 Cs contaminated samples [9,59,62]. The lower hydration energies of the ionic cesium resulted in the augmented occurrence of cesium in the interlayer or frayed edge sites of the soil particles [45][46][47].…”

“…Sequential extraction methods have often been used to evaluate the bioavailability and mobility of radionuclides in soils based on the distribution of the physico-chemical forms of radiocesium. The solid-phase fractionation patterns of 133 Cs-loaded and simulated Japanese soils follow fractionation patters that are similar to 137 Cs, with a higher rate of accumulation in the residual soil fraction [9,[58][59][60].…”