Migration and bioavailability of 137Cs in forest soil of southern Germany

Hochschule Ravensburg-Weingarten, University of Applied Sciences, Germany.
Journal of Environmental Radioactivity (Impact Factor: 2.48). 02/2009; 100(4):315-21. DOI: 10.1016/j.jenvrad.2008.12.010
Source: PubMed


To give a quantitative description of the radiocaesium soil-plant transfer for fern (Dryopteris carthusiana) and blackberry (Rubus fruticosus), physical and chemical properties of soils in spruce and mixed forest stands were investigated. Of special interest was the selective sorption of radiocaesium, which was determined by measuring the Radiocaesium Interception Potential (RIP). Forest soil and plants were taken at 10 locations of the Altdorfer Wald (5 sites in spruce forest and 5 sites in mixed forest). It was found that the bioavailability of radiocaesium in spruce forest was on average seven times higher than in mixed forest. It was shown that important factors determining the bioavailability of radiocaesium in forest soil were its exchangeability and the radiocaesium interception potential (RIP) of the soil. Low potassium concentration in soil solution of forest soils favors radiocaesium soil-plant transfer. Ammonium in forest soils plays an even more important role than potassium as a mobilizer of radiocaesium. The availability factor - a function of RIP, exchangeability and cationic composition of soil solution - characterized reliably the soil-plant transfer in both spruce and mixed forest. For highly organic soils in coniferous forest, radiocaesium sorption at regular exchange sites should be taken into account when its bioavailability is considered.

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    • "Further, the laboratory studies revealed that clay mineral composition, especially abundance of the micaceous clay mineral (or illite), can also have influence on long-term 137 Cs stabilization (Konopleva et al. 2009; Giannakopoulou et al. 2012), although its effects on initial Cs dynamics have not been observed from the field survey (Matsunaga et al. 2013). Of a variety of clay minerals, mica and its weathered products may play important roles in Cs retention in soil profiles due to a high layer charge of 2:1 phyllosilicate (Hird et al. 1996; Konopleva et al. 2009). Illite exhibits the highest selectivity of Cs sorption (Delvaux et al. 2001). "
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    ABSTRACT: In forest soils contaminated by radiocesium (134Cs and 137Cs), deposition from the Fukushima nuclear accident, clay minerals might play important roles in long-term cesium (Cs) dynamics through sorption. To determine whether radiocesium can be retained within the organic layer and the upper mineral soil layers in the Fukushima region, we investigated the vertical distribution of 134Cs and 137Cs and the clay mineral composition in five soil profiles of varying radiocesium deposition levels and vegetation types. X-ray diffraction analyses and oxalate extraction suggested that hydroxy-interlayered vermiculites and shortrange-ordered aluminum (Al) and iron (Fe) compounds (i.e, allophane and ferrihydrite) were major clay mineral species of the upper soil layers. The vertical soil distribution of 134Cs and 137Cs suggested that most of them were retained in the organic layer and upper mineral soil layer under different levels of deposition. Within 1.5 years after the accident, both 134Cs and 137Cs were leached from the organic layer, and most of these (59–73%) were accumulated in the upper soil layer (0–5 cm). The proportion of 137Cs (or 134Cs) leaching from the organic layer was greater at sites receiving greater amounts of recipitation. The substantial accumulation of 137Cs in the upper soil layer, irrespective of the 137Cs deposition level or clay mineral composition, suggests that sorption capacities of clays and organic matter are sufficiently high to retain 137Cs in the surface soil during at least the initial stage of contamination.
    Full-text · Article · Nov 2014 · Soil Science and Plant Nutrition
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    • "91 ) reported as 1 . 8 mm y À1 . Despite the likely differ - ences in the study sites , the pre - Fukushima 137 Cs peak in our study site has been expected to be relatively deeper but did not show a significant change . This can be explained by efficient progressive fixation of radiocesium by clay minerals even if present in organic - rich soils ( Konopleva et al . , 2009 ) over time that retards the migration and increases its residence half time ( Bunzl et al . , 1995 ) . More interestingly , almost all of the pre - Fukushima 137 Cs was contained in a soil layer in which the OM content constituted more than 10% ( Table 1 and Fig . 4a ) . Indeed , several studies have demonstrated that forest soils have"
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    ABSTRACT: This study deals with the description of the vertical distribution of radiocaesium ((137)Cs and (134)Cs) in a representative coniferous forest soil, investigated 10 months after the Fukushima radioactive fallout. During soil sampling, the forest floor components (understory plants, litter (Ol-) and fermented layers (Of)) were collected and treated separately. The results indicate that radiocesium is concentrated in the forest floor, and high radiocesium transfer factor observed in the undergrowth plants (3.3). This made the forest floor an active exchanging interphase for radiocesium. The raw organic layer (Ol + Of) holds 52% (5.3 kBq m(-2)) of the Fukushima-derived and 25% (0.7 kBq m(-2)) of the pre-Fukushima (137)Cs at the time of the soil sampling. Including the pre-Fukushima (137)Cs, 99% of the total soil inventory was in the upper 10 cm, in which the organic matter (OM) content was greater than 10%, suggesting the subsequent distribution most likely depends on the OM turnover. However, the small fraction of the Fukushima-derived (137)Cs at a depth of 16 cm is most likely due to the infiltration of radiocesium-circumscribed rainwater during the fallout before that selective adsorption prevails and reduces the migration of soluble (137)Cs. The values of the depth distribution parameters revealed that the distribution of the Fukushima-derived (137)Cs was somewhat rapid.
    Full-text · Article · Jul 2014 · Journal of Environmental Radioactivity
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    • "In addition, on the basis of litter decomposition studies in temperate Japanese forests located at latitudes similar to those in the study area (Ono et al., 2011), the mean residence time of litter in the studied forests could be around 2.5 years. Therefore, it is reasonable that the litter decomposition effect (Konopleva et al., 2009) does not appear at this time. Continuous observations are required to see how the large amount of "
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    ABSTRACT: Effect of intense rainfall on the distribution of Fukushima-accident-derived 137Cs in soil was examined. Inventories and vertical distributions of 137Cs in soils were determined at 15 locations (including croplands, grasslands, and forests) in Fukushima city in the post-rainy season, approximately 4.5 months after the accident, and were compared with those in the pre-rainy season determined in our former study. The 137Cs inventory levels scarcely changed between points in time spanning the first rainy season after the accident. Moreover, the majority of 137Cs remained stored in the aboveground vegetation and in the upper 5 cm of soil layer at undisturbed locations in the post-rainy season. A more quantitative analysis with the characterization of the vertical profile of 137Cs using the relaxation length confirmed that the vertical profile was almost unchanged at most locations. Accordingly, it is concluded that rainfall during the rainy season had a limited effect on 137Cs distribution in the soil, indicating the very low mobility. Chemical extraction of 137Cs from selected soil samples indicated that 137Cs in the soil was barely water soluble, and even the fraction extracted with 1 M ammonium acetate was only approximately 10%. This further supports the low mobility of 137Cs in our soils. Soil mineralogical analyses, which included the identification of clay minerals, suggested that smectite and mica could lower the exchangeable fraction of 137Cs. However, no direct relationship was obtained between mineral composition and 137Cs retention in the upper soil layer. In contrast, positive correlations were observed between 137Cs extractability and soil properties such as pH, organic matter content, finer-sized particle content, and cation-exchange capacity. These results suggest that the mineralogical effect on the firm fixation of 137Cs on soil constituents may be masked by the non-specific adsorption offered by the physicochemical properties of the soils.
    Full-text · Article · Feb 2013 · Science of The Total Environment
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