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Radio-caesium Fixation Dynamics: Measurement in Six Cumbrian Soils
Abstract
Five peat soils and a mineral soil were artificially contaminated with 137Cs. Soil solution activity and radio–lability of 137Cs were monitored over 709 days to quantify progressive 137Cs fixation. The peat soils fixed large amounts of 137Cs, but less than the mineral soil did. Distribution coefficients (Kd, cm3 g−1) ranged from 30 to 5000 at the end of equilibration. A labile 137Cs distribution coefficient, Kdt, was estimated by a method involving solid ⇌ solution equilibration in dilute solution.
In a separate study several concentrations of KCl were added to soils in increasing concentration both before and after the addition of 137Cs. Differences in apparent adsorption strength of radiocaesium indicated that K+ induced the collapse of expanded mineral interlayers, thereby trapping ions. It seemed that I37Cs adsorbs at sites in the small micaceous clay fraction of the peat soils.
The different rates of 137Cs adsorption and fixation in the peat and mineral soils, in which the rate of access of 137Cs to fixation sites in peat soils is less, seems to have been caused partly by lack of K, and partly by the scarcity of fixation sites.
... 1-4). The K supply from K-fertilizer and/or rice residue (i.e., straw, stump, and root) would have induced the collapse of interlayers of 2:1-type clay minerals, and some part of exchangeable Cs would have been strongly retained at newly-formed Cs-selective sites (Absalom et al., 1995;Ogasawara et al., 2019;Kitayama et al., 2020) or fixed into collapsed interlayers (Absalom et al., 1995). ...
... 1-4). The K supply from K-fertilizer and/or rice residue (i.e., straw, stump, and root) would have induced the collapse of interlayers of 2:1-type clay minerals, and some part of exchangeable Cs would have been strongly retained at newly-formed Cs-selective sites (Absalom et al., 1995;Ogasawara et al., 2019;Kitayama et al., 2020) or fixed into collapsed interlayers (Absalom et al., 1995). ...
... An increase in exchangeable 137 Cs would have reflected an increase in soil solution 137 Cs. In fact, Absalom et al. (1995) reported an increase in the solid/liquid distribution coefficient of radiocesium with increasing solution K. Their results strongly suggest that the decrease in soil solution K increases the soil solution radiocesium. Furthermore, an increase in soil solution radiocesium proportionally influences the uptake of radiocesium by crops, whereas the decrease in soil solution K exponentially influences the uptake of radiocesium (Zhu and Smolders, 2000). ...
Field and pot experiments were conducted to evaluate the effectiveness of coarse Finnish phlogopite application to reduce radiocesium uptake by paddy rice (Oryza sativa L.). The application of phlogopite was expected to reduce radiocesium uptake by crops through K supply and radiocesium retention. Three fields were set in Fukushima Prefecture, and coarse (mean particle size of 450 μm) phlogopite from Siilinjärvi (Finland) was applied at a rate of 5 t ha-1. Paddy rice was cultivated for 2-4 successive years. In all fields, the average 137Cs transfer factor (TF) of brown rice harvested from plots with added phlogopite was significantly lower than that of brown rice from plots without added phlogopite over the 2-4-year experiments. TF was decreased by up to 80% following phlogopite application, without an adverse effect on yield. Exchangeable K and soil solution K were higher in the soils with added phlogopite, suggesting K released from phlogopite reduced 137Cs uptake by paddy rice. Moreover, in a pot cultivation experiment, even when 55% of the total K was removed from phlogopite prior to application, the TF in pots with phlogopite application was less than half of that in pots without added phlogopite. The results from the field study and the pot cultivation experiment suggested that the application of Finnish phlogopite is effective to reduce the TF of brown rice. Exchangeable K and tetraphenylborate-extractable-K (TPB-K) at rooting stage, and soil solution K at tillering and heading stages showed significant negative correlation with TF. TPB-K was significantly positively correlated with soil solution K at tillering stage and heading stage, whereas exchangeable K at rooting stage did not exhibit significant correlation with soil solution K at heading stage. The results suggest that TPB-K is more reliable than exchangeable K, which could facilitate as a basis of K fertilizer recommendation for radiocesium-contaminated fields.
... 137 Cs adsorbed onto soils can be classified into three forms with different mobility. [12][13][14][15][16][17] The first (designated here as RES-137 Cs) is bound to nonspecific ion exchange sites (regular exchange sites; RESs), which exhibit low selectivity for Cs and are located at planar sites in clays and organic matter. 14,17 The second (FES-137 Cs) is bound to frayed edge sites (FESs), which are located at the wedge zones of 2:1 micaceous phyllosilicates (e.g., vermiculite and illite) and selectively sorb Cs [12][13][14][15][16][17] and to a lesser extent ammonium and K. 14 If the concentration of these cations is sufficient, their specific sorption in wedge zones induces the collapse of FESs. ...
... [12][13][14][15][16][17] The first (designated here as RES-137 Cs) is bound to nonspecific ion exchange sites (regular exchange sites; RESs), which exhibit low selectivity for Cs and are located at planar sites in clays and organic matter. 14,17 The second (FES-137 Cs) is bound to frayed edge sites (FESs), which are located at the wedge zones of 2:1 micaceous phyllosilicates (e.g., vermiculite and illite) and selectively sorb Cs [12][13][14][15][16][17] and to a lesser extent ammonium and K. 14 If the concentration of these cations is sufficient, their specific sorption in wedge zones induces the collapse of FESs. 13,15,16 When FESs collapse, FES- 137 Cs is fixed and changed to a third form (Fix-137 Cs). ...
... 14,17 The second (FES-137 Cs) is bound to frayed edge sites (FESs), which are located at the wedge zones of 2:1 micaceous phyllosilicates (e.g., vermiculite and illite) and selectively sorb Cs [12][13][14][15][16][17] and to a lesser extent ammonium and K. 14 If the concentration of these cations is sufficient, their specific sorption in wedge zones induces the collapse of FESs. 13,15,16 When FESs collapse, FES- 137 Cs is fixed and changed to a third form (Fix-137 Cs). 13,15 Because trace amounts of 137 Cs due to contamination are rapidly trapped by FESs, 18 Cs is usually rare in soil. ...
To evaluate the mobility and bioavailability of 137Cs in soils, we compared the extraction of 137Cs with stable Cs and ammonium solutions from 137Cs-contaminated minerals and soils. The extraction yields of 137Cs with stable Cs were significantly lower than those with ammonium for minerals with frayed edge sites, but such differences were not observed for minerals without frayed edge sites. The amount of 137Cs extracted with stable Cs from soils was lower than, or equal to, that extracted with ammonium. The above results suggest that stable Cs extracted the 137Cs from easily accessible sites. Plant available 137Cs was assessed using Kochia (Bassia scoparia) cultivated in pots of contaminated soils, and compared with soil parameters including extractable 137Cs and K, and radiocesium intercept potential. The 137Cs/K ratio extracted with stable Cs solution was found to be a potential index for evaluation of the easily mobile and bioavailable fraction of 137Cs in soil.
... Nevertheless, selecting potential technologies will consider safety criteria, economic considerations, the comparison of treatment and disposal costs, and the public acceptance of various options (IAEA, 2023). The r-Cs tend to be more concentrated in silt and clay soil fractions compared to pebbles or sand, as attributable to the fact that fine soil particles offer a greater surface area for adsorption compared to an equal volume of larger soil particles (Absalom et al., 1995;Eagle et al., 1993;Rigol et al., 2002). The binding of 137 Cs with clay-sized soils (< 2 μm) is reported to be stronger than with larger-sized particles (Spezzano, 2005;Tsukada et al., 2008), proving resilient against removal by conventional methods (Dushenkov et al., 1999;Kozai et al., 2012). ...
... PSD results revealed that all soil samples have a similar silty-clay-loam type textural classification containing higher clay and silt contents (ranging from 413 to 610 g kg − 1 ). The total Al content in all soil samples exceeded that of Fe, which suggests a potential link to soil acidification due to the increased Al concentration (Absalom et al., 1995). ...
... This consecutive field work from 2015 to 2021 indicates that 137 Cs in the soil was gradually transformed to a form more difficult to be absorbed by rice, that is considered due to gradual radiocesium fixation with ageing, as shown by Roig et al. (2007), Absalom et al. (1995), Yamaguchi et al. (2016Yamaguchi et al. ( , 2019 and Takeda et al. (2013Takeda et al. ( , 2020 who investigated fixation mechanism and conditions in detail mainly under artificial conditions. However, their data are from those within 3 years from radiocesium fall-out or addition to soils. ...
... However, their data are from those within 3 years from radiocesium fall-out or addition to soils. Our work showed that phytoavailability of 137 Cs assessed by TF of rice and exchangeable 137 Cs fraction of the soil continue to decrease even after 4-8 years from the fall-out in an actual paddy field in Iitate Village in Fukushima Prefecture This slow decrease may be partly due to the type of soil of the allophanic Andosol of the test field, lower ageing speed, compared to mineral soil (Absalom et al. 1995;Yamaguchi et al. 2019), and also due to probable presence of 137 Cs in organic materials not exchangeable in soil (co. 6% in case of Date-city soil, Tsukada 2014) and 137 Cs in harvest residue returned and incorporated outer organic matters, which may gradually be transformed exchangeable and further fixed to mineral content in the soil. ...
We performed consecutive field trials of rice cultivation for 10 years (2012–2021) to elucidate how to reduce radiocesium absorption by rice and to resume safe rice cultivation in a partially decontaminated paddy soil in the Iitate Village in Fukushima prefecture, Japan. Our previous report (Ii and Tanoi (2016) Consecutive field trials of rice cultivation in partially decontaminated paddy fields to reduce radiocesium absorption in the Iitate village in Fukushima prefecture. In: Nakanishi TM, Tanoi K (eds) Agricultural implications of the Fukushima nuclear accident. Springer, Tokyo, pp 55–76) of the results in 2012 and 2013 showed that K fertilization can reduce the radiocesium level of the brown rice less than the standard for food (100 Bq/kg). This report of the subsequent years (2014–2021) shows more than 80% reduction of ¹³⁷ Cs concentration in the brown rice and straw at KCl fertilized and straw plowed-in paddy soil. The transfer factor of ¹³⁷ Cs from soil to brown rice reduced from 0.0022 in 2015 to 0.0003 in 2019 and that to straw reduced from 0.0262 in 2015 to 0.0028 in 2019, respectively. Exchangeable positive ions of the soil were also analyzed. Multiple regression analyses of all data of transfer factor in 2015–2019 to year (ageing) and exchangeable K ion as variables show that the main causal factor is year (ageing) with some supportive effect of increase of exchangeable K ion. This implicates that radiocesium in soil was gradually transformed to a form more difficult to be absorbed by rice, that is, ¹³⁷ Cs immobilization or fixation on clay minerals by ageing, not only in early years after the accident (2011–2015), but also in later years (2015–2019). This implication was supported by comparative analysis of exchangeable ¹³⁷ Cs of dry soil of 2017, 2018, and 2019 (Ii et al., Radioisotopes 70:63–72, 2021). The results in 2020 and 2021 show those transfer factors have reached at bottom levels. Further this field work also shows the robustness of the rice cultivation that we could harvest rice far below the safety standard, even though the paddy field suffered floods by typhoons in September 2015 and in October 2019.
... Rice radiocesium absorption is not significantly different among these cultivars. 11) Table 1 were not included in this note, since the fields were indicates that 137 Cs in the soil was gradually transformed to a form more difficult to be absorbed by rice, that is considered due to gradual radiocesium fixation with ageing, as shown by Roig et al.,4) Absalom et al., 14) Yamaguchi et al. 15,16) and Takeda et al. 17,18) who investigated fixation mechanism and conditions in details mainly under artificial conditions. However, their data are from those within 3 years from radiocesium fall-out or addition to soils. ...
... Our work showed that phytoavailability of 137 Cs assessed by TF of rice and exchangeable 137 Cs fraction of the soil continue to decrease even after 4 to 8 years from the fall out in an actual paddy field in Iitate Village in Fukushima Prefecture This slow decrease may be partly due to the type of soil of the allophanic Andosol of the test field, lower ageing speed, compared to mineral soil, 14,15) and also due to probable presence of 137 Cs in organic materials not exchangeable (co. 6% in case of Date-city soil 7) ) in soil and 137 Cs in harvest residue returned which may gradually be transformed exchangeable and further fixed to mineral content in the soil. ...
We performed consecutive field trials of rice cultivation to monitor radiocesium contamination in harvested rice from 2012, in the Iitate Village in Fukushima Prefecture, where people were forced to be evacuated due to high level of radioactive contamination caused by the disaster at the Fukushima Dai-ichi Nuclear Power Plant of Tokyo Electric Power. The early year results (2012–2013)1, 2) showed the radiocesium concentration in the brown rice was reduced depending on the decontaminated level of paddy soil and on the exchangeable K content of the soil. This report of later year results (2015–2019) showed further more than 80% reduction of ¹³⁷Cs concentration in the brown rice and straw at KCl fertilized paddy soil, in spite of little reduction of ¹³⁷Cs concentration of the soil. The transfer factor of ¹³⁷Cs from soil to brown rice reduced from 0.0022 in 2015 to 0.0003 in 2019 and that to straw reduced from 0.0262 in 2015 to 0.0028 in 2019, respectively. Exchangeable positive ions of the soil were also analyzed. Multiple regression analyses of all data of transfer factor in 2015 to 2019 to year (ageing) and exchangeable K ion as variables shows that the main causal factor is year (ageing) with some supportive effect of increase of exchangeable K ion. This implicates that radiocesium in soil was gradually transformed to a form more difficult to be absorbed by rice, that is, ¹³⁷Cs immobilization or fixation on clay minerals by ageing, not only in early years after the accident (2011–2015), but also in later years (2015–2019). This implication was supported by comparative analysis of exchangeable ¹³⁷Cs of dry soil of 2017, 2018 and 2019.
... watershed runoff and erosion) (Ehlken and Kirchner, 2002;IAEA, 2010;Mück, 2003). In addition to those processes, it is well known that the bioavailability of radiocaesium in soil decreases with time due to its diffusion into the illite lattice (Absalom et al., 1995;Smith et al., 1999), a process commonly known as "aging". ...
... The rates of decline of 137 Cs activity concentrations in soil are generally slower than observed in milk or grass with also smaller fluctuations over time for all studied sites. Such observations in fact may be likely attributed to the slow irreversible fixation of 137 Cs in soil that is frequently reported as a limiting factor of bioavailability and mobility of 137 Cs (Absalom et al., 1995;Smith et al., 1999). We may also notice that the relatively large spatial variability in the measurements of 137 Cs activity concentrations at CRM, NOG, BUG sites (where soil samples were collected from several observation plots) surprisingly does not affect the emergence of clear decline trends. ...
Long term radioactivity monitoring programs contribute to the understanding of the behavior of radionuclides in the environment. This work aims to investigate the long term behavior of Cesium-137 in pasture ecosystem (root soil, grass and cow's milk) by using of more than twenty five years monitoring data collected at ten of French pasture sites contaminated by atmospheric fallouts from Chernobyl and nuclear atmospheric tests. We estimated with a simple exponential model the long term effective half-lives of radiocesium in root soil, grass vegetation and cow's milk along with their associated uncertainties. The average values of the effective half-lives over all the investigated sites were determined as 17, 11 and 9 years for soil, grass and milk respectively. Those values compare favorably to those estimated in previous studies in literature. These findings further enable us to quantify the decrease of 137Cs bioavailability which ranges from 0.008 to 0.044 year−1 with an average value of 0.026 year−1 (i.e. effective half lives ranging from 16 to 87 years with an average value of 26 years in soil).
... It was proposed that at a low concentration of Cs (< 1.0 × 10 −6 M), Cs sorption to minerals is unaffected by Na + or H + but reduced by a high concentration of K + (Fuller et al., 2014). Absalom et al. (1995Absalom et al. ( , 1999 suggested that the bioavailability and environmental mobility of radiocesium decline with time elapsed after deposition in the soil. This is known as the "aging effect", and this phenomenon was observed in various plants and contaminated soil in the studies of the accident at the Chernobyl Nuclear Power Plant in 1986 (Rigol et al., 1999;Roig et al., 2007). ...
... Our results showed that effective desorption of 137 Cs in WB occurred using acidic solutions, but no clear aging effect was seen in the experiments (Figs. 1 and 5). However, desorption by acids was not completed for the radioactive WB from actual contaminated soil at Fukushima Prefecture (Fig. 5), which may suggest an aging effect with an even longer time as reported in previous studies (Absalom et al., 1995(Absalom et al., , 1999Takeda et al., 2013). Dissolution of the silicate layer seems to be the only process that effectively removes sorbed radiocesium in WB, although definitely such a process using strong acids is harmful to the environment. ...
For the better understanding of radioactive contamination in Fukushima Prefecture at present and in future, Cs desorption experiments have been conducted mainly using weathered biotite (WB) collected from Fukushima Prefecture and considering the actual contamination level (∼10-10 wt%) of radiocesium in Fukushima Prefecture. In the experiments, 137Cs sorbed to WB by immersing in 137Cs solution for one day was mostly desorbed by solutions of 1 M NaNO3, 1 M LiNO3, 10-1 M HCl, and 10-1 M HNO3, although it was barely desorbed by 1 M KNO3, 1 M CsNO3, 1 M NH4NO3, and natural seawater. X-ray diffraction analysis of WB after immersing in these solutions suggested that the collapse of the hydrated interlayers in WB suppressed the desorption of Cs. On the other hand, 137Cs was barely desorbed from WB even by the treatments with solutions of NaNO3 and LiNO3 if the duration for the sorption was longer than approximately two weeks, as well as radioactive WB collected from actual contaminated soils in Fukushima Prefecture. This result implies that Cs sorbed in WB became more strongly fixed with time. Probably removal of radiocesium sorbed in weathered granitic soil at Fukushima Prefecture is difficult by any electrolyte solutions, as more than seven years have passed since the accident.
... Cesium is known to be sorbed to clay minerals, particularly micaceous minerals, in soils (Absalom et al., 1995;McKinley et al., 2001;Nakao et al., 2008). When Cs þ is sorbed to so-called frayed edges of micaceous minerals located in peripheral wedged regions of the minerals, where the interlayer spaces are partly expanded due to weathering, the sorption causes partial collapse of the interlayer and induces strong fixation of Cs þ (Sawhney, 1972). ...
... A few studies have shown slow desorption of Cs from sediments or micaceous minerals, based on desorption experiments over two weeks (De Koning and Comans, 2004;Liu et al., 2003). Moreover, it is reported that an increase of sorption time slows down subsequent Cs þ desorption and leads to the irreversibility of the sorption (Absalom et al., 1995;Shenber and Eriksson, 1993;Takeda et al., 2013). This means that the distribution of Cs þ in soils may change to more stable forms with time and that Cs þ desorption evaluated in a relatively short period of time can be underestimated. ...
Understanding the behaviors of Cs+ in soils is crucial for evaluation of the impacts of disposal of soils contaminated by radiocesium, 137Cs. The desorption rate of Cs+ evaluated in relatively short periods of time may not be adequate for such a purpose. In this study, we investigated long-term desorption kinetics of 137Cs and 133Cs from soils collected in Fukushima Prefecture by batch desorption experiments in the presence of cation exchange resin as a sorbent. The sorbent can keep the concentration of Cs+ in the aqueous phase low and prevent re-sorption of desorbed Cs+. Up to 60% of 137Cs was desorbed after 139 d in dilute KCl media, which was larger than the desorption by conventional short-term extraction with 1 M ammonium acetate. Desorption of 137Cs continued even after this period. It was also found that high concentration of K+ prevented desorption of Cs+ in the initial stage of desorption, but the effect was alleviated with time. The desorbed fraction of stable Cs was smaller than that of 137Cs. This indicated that 137Cs may gradually move to more stable states in soils. The half-life of 137Cs desorption from the slowest sorption site was estimated to be at least two years by a three-site desorption model.
... In a contaminated soil, transfer of Cs to plants depends on both the capacity of the soil to provide Cs to the soil solution from where plants can take it up and on the capacity of the plants to absorb it. Cs has been shown to be strongly adsorbed at the surface of soil mineral or organic constituents (Absalom et al., 1995;McKinley et al. 2001;Kruglov et al. 2008). Clays are generally considered as the main sorbent of Cs in soils (Shenber, 1993;Qin et al., 2012;Hirose et al., 2015), through the involvement of several sorption sites, such as « Frayed Edge Sites » (FES) or other cationic exchange sites (Sawhney, 1972;Poinssot et al., 1999;Zachara et al., 2002;Missana et al., 2014a;Okumura et al., 2018). ...
... This effect predominates over other soil parameters. Previous studies have reported that Cs sorption in mineral soils get affected by cation exchange capacity (Absalom et al., 1995;Cremers et al., 1988;Giannakopoulou et al., 2007). In the present study, it is found that within cation exchange capacity, the predominating K + ion affects Cs sorption. ...
Meeting the requirement of high specific activity of radioisotopes and carrying out comprehensive research and development activities in the nuclear field, different nuclear facilities, including their waste disposal facilities, are going to be operational at Visakhapatnam, India. Due to environmental processes, the engineered disposal modules may lose their structural integrity and may release some radioactivity to the geo-environment. The subsequent migration of radionuclides reaching the geological environment will be governed by the distribution coefficient (Kd). Cs was chosen for the sorption study in two soil samples (soil-29 and 31) and to estimate the Kd in all the 40 soil samples through the laboratory batch method at the new campus of DAE, Visakhapatnam, India. Different soil chemical parameters like pH, organic matter, CaCO3, and cation exchange capacity were determined in 40 soil samples and their effect on Cs sorption was investigated. The effect of solution pH and initial concentration of Cs on sorption was also studied. The results show that the sorption of Cs increases with increasing pH. The Cs sorption was well explained by Freundlich and Dubinin-Radushkevich (D-R) isotherm models. Site-specific distribution coefficients (Kd) were also estimated and the values were found to vary from 75 ± 1 to 540 ± 12 L kg⁻¹. The observed wide variation in Kd could be due to large variations in the physico-chemical properties of collected soil. The competitive ions effect study suggests that K⁺ has higher interference for Cs⁺ sorption as compared to Na⁺. The present study results will help assess the environmental impact due to Cs release in any unforeseen scenario and in planning effective remediation strategies.
... The correlation of Exf-137 Cs with the Ne-Ks by the TPB methods within the KH field indicates that 137 Cs was fixed or released together with the recently fixed K. Two possible mechanisms were considered for this. First, expanded interlayers of vermiculites and weathered micas are collapsed through K fixation and then trap labile RCs adsorbed there (Absalom et al., 1995). Second, Cs-selective sites can increase when K application collapses these interlayers (Murota et al., 2020). ...
Non-exchangeable K released from soil minerals can reduce radiocesium transfer to plants, as well as exchangeable K. We investigated the effect of non-exchangeable K on radiocesium transfer to soybean, and the non-exchangeable K extraction method most suitable for estimating the transfer risk. In Fukushima Prefecture, Japan, 106 soils were collected from 89 soybean fields during 2014–2018 to analyze non-exchangeable K contents using three methods: boiling nitric acid extraction, tetraphenyl‑boron extraction, and mild tetraphenyl‑boron extraction. The non-exchangeable K contents quantified by the former two methods were dependent on the amount of micas, which are K-bearing minerals. The non-exchangeable K content by mild tetraphenyl‑boron extraction depended on the amount of K fertilizer application and K-fixing minerals but not on micas, indicating that it reflects fertilizer K fixed by the minerals. The soil-to-plant transfer factor of radiocesium was most correlated with the non-exchangeable K content by the mild extraction (rs = −0.67). This correlation was also stronger than that between exchangeable K and the transfer factor (rs = −0.40). As non-exchangeable K content increased, the exchangeable radiocesium fraction decreased, indicating that radiocesium was fixed together with K. Additionally, multiple regression analysis indicated that non-exchangeable K by the mild extraction significantly decreased the transfer factor even if the exchangeable radiocesium fraction was kept constant. Thus, the fixed K was considered to repress radiocesium transfer to soybean through both radiocesium fixation and K supply. With the criterion of total extracted K, the sum of exchangeable and non-exchangeable K, as 65 mg K2O 100 g ⁻¹ by the mild extraction, fields with high and low transfer factors were able to be differentiated more effectively than with a current criterion of exchangeable K as 50 mg K2O 100 g ⁻¹. The results revealed that mild tetraphenyl‑boron extraction is effective for estimating radiocesium transfer to soybean.
... In contaminated soil, transfer of Cs to plants depends on both the capacity of the soil to provide Cs to the soil solution from where plants can take it up and the capacity of the plants to absorb it. Cs has been shown to be strongly adsorbed at the surface of soil minerals or organic constituents (Absalom et al., 1995;McKinley et al., 2001;Kruglov et al., 2008). Clays are generally considered as the main sorbent of Cs in soils (Shenber and Eriksson, 1993;Qin et al., 2012;Hirose et al., 2015), through the involvement of several sorption sites, such as "Frayed Edge Sites" (FES) or other cationic exchange sites (Sawhney, 1972;Brouwer et al., 1983;Poinssot et al., 1999;Bradbury and Baeyens, 2000;Zachara et al., 2002;Missana et al., 2014a;Cherif et al., 2017;Okumura et al., 2018). ...
Cs is one of the most persistent radioactive contaminants in soil after a nuclear accident. It can be taken up by plants and enter the human food chain generating a potential human health hazard. Although a large amount of literature has highlighted the role of the different processes involved in Cs uptake by plants, there is still no simple way to predict its transfer for a specific plant from a particular soil. Based on the assumption that the concentration ratio (CR) of Cs can be predicted from one plant taxon if the CR of another taxon is known and taken as reference, whatever the supporting soils, a series of plant/soil Cs transfer experiments were performed on Rhizotest during 21 days using three soils with different textures, clay and organic matter contents and two plants (millet and mustard) with potentially contrasting Cs uptake capacity based on their phylogeny. CRs of each plant varied by 2–3 orders of magnitude depending on the soil and contrary to expectations, the CRs of mustard were either higher (for clay soil), equal (for clay-loam soil) or lower (for sandy soil) than the one of millet. Considering Cs availability in soils and defining a new CR based on the amount of Cs available in the soil (CRavail) decreased the range of variation in CR between the different soil types for a given plant by one order of magnitude. Differences in Cs (and K) translocation to shoots, possibly specific to millet within Poales, could partly explain the relative CRs of millet and mustard as a function of soils.
... It is well known that there is considerable variation in the soil to plant transfer of radiocaesium. This is due to differences in pH, potassium status, clay and organic matter content (Absalom, JP., Young, SD., Crout, NMJ., 1995). Table 4.20. ...
... Despite findings indicating that bioavailability of radiocesium in soil decreases with time (Absalom et al., 1995;Brimo et al., 2019;Smith et al., 1999), these models have been often developed and tested against data sets mostly limited to laboratory experiments on relatively short time scales (i.e. from a few days to a few years). Thus, the validity of these models under real field conditions and on longer time scales (i.e. ...
The aim of this study was to evaluate and improve the accuracy of the semi-mechanistic models used in regulatory exposure assessment tools, to describe the transfer factors of 137 Cs from pasture soils to grass observed in different grazing areas of France between 2004 and 2017. This involved a preliminary parameterization step of the dynamic factor describing the ageing of radiocesium in the root zone using a Bayesian approach. A data set with mid-term (10 years about) and long term (more than 20 years) field and literature data from 4 European countries was used. A double kinetics of the bioavailability decay was evidenced with two half-life periods equal to 0.46 ± 0.11 yr and 9.57 ± 1.12 yr for the fast and slow declining rates respectively. We, then, tested a few existing alternative models proposed in literature. The comparison with field data showed that these models always underestimated the observations by one to two orders of magnitude, suggesting that the solid-liquid partition coefficient (Kd) was overestimated by models. The results suggest that semi mechanistic models might fail in the long-term prediction of the radionuclide transfer from soil-to-plant in the food chain. They highlight the need to calculate Kd using easily exchangeable 137 Cs (i.e. labile fraction) rather than total soil 137 Cs.
... Because of this, Cs sorption to FES is a slow dynamic process, resulting in the fraction of sorbed Cs that virtually is irreversibly sorbed and no longer participates in the partition between the solid and liquid phases to increase with time. This process is known as sorption aging and enhances the fraction of irreversibly bound Cs (Absalom et al., 1995;Roig et al., 2007;Wang and Staunton, 2010;Wampler et al., 2012Söderlund et al., 2016. Therefore, important considerations affecting the risk posed by Cs contaminated soils is whether there has been a short or long Cs contact time with the soil and whether 2:1 clays are present. ...
The solid-liquid distribution coefficient (Kd) is a key input parameter in radioecological models. However, its large variability hampers its usefulness in modelling transport processes as well as its accuracy in representing soil-radionuclide interactions. For the specific case of radiocaesium, the analyses of a Cs Kd soil dataset (769 entries) showed that values varied over a five order of magnitude range, and the resulting Cs Kd best estimate (calculated as a geometric mean = 2.5 × 103 L kg-1) lacked reliability and representativity. Grouping data and creation of partial datasets based on the experimental approach (short-term (< ~1 yr) vs. long-term experiments (> ~1 yr)) and soil factors affecting Cs interaction (i.e., the ratio of the radiocaesium interception potential (RIP) to the potassium content in soil solution (Kss); organic matter content (OM) and soil texture) succeeded in reducing variability a few orders of magnitude, with Cs Kd best estimates also differing by one-two orders of magnitude depending on the type of soil and experimental approach. The statistical comparison of the Cs Kd best estimates and related cumulative distribution functions of the partial datasets revealed a relevant effect of the sorption dynamics on Cs Kd values (with long-term values systematically higher than short-term ones), and that the RIP/Kss ratio was an excellent predictor of Cs Kd for short-term scenarios, whereas the RIP parameter could be predicted on the basis of texture information. The OM threshold to distinguish between OM threshold to distinguish between Mineral and Organic soils subclasses, regarding Cs interaction was determined to be 50% and 90% OM for short- and long-term scenarios, respectively. It was then recommended to select the Cs Kd input data depending on the soils and scenarios to be assessed (e.g., short- vs. long-term; OM %) to improve the reliability and decrease the uncertainty of the radioecological models.
... As a result of wet and dry depositions, soil particles have been contaminated by caesium isotopes and other radioactive nuclides. Interaction of radiocaesium with the various components of soils (sand, silt, and clay minerals) has been an active research topic over past decades (Sawhney, 1972;Comans and Hockley, 1992;Absalom et al., 1995;McKinley et al., 2001;Nakao et al., 2008;Saito et al., 2014;Murota et al., 2016;Ezzat et al., 2017). It has been reported that micaceous clay minerals common in soils have a stronger affinity to adsorb caesium in their interlayer spaces than other soil components; hence relatively high radioactive soil particles are existed (Hosoda et al., 2012). ...
Radioactive caesium was released during the accident of Fukushima Dai-ichi nuclear power plant (FDNPP) into the surrounding environment. In the current work, radiocaesium micro-particles (CsMPs) and radiocaesium-rich soil particles were selectively separated from soil particles as well as from each other using autoradiography-based procedure. The applied separation scheme is based on water dilution followed by drying of the soil sample prior to imaging plate autoradiography. The SEM/EDS investigation of the individual CsMPs showed that these particles have a silicate glass structure and vary in shape with a diameter less than 10 μm. For the first time, a two-stage formation mechanism was suggested for a CsMP based on shape and structure heterogeneity of its two parts. Perfect spherical core might be formed in the first stage with a remarkable lower content of Al, and relatively higher concentrations of Si and K than an outer angulated structure, which might be attached to the core sphere during a late stage.
The radiocaesium-rich soil particles have bigger size than CsMPs and have a plate-like structure with cleavages inside the grains, which suggest that these particles might be a weathered biotite. The average radioactivity ratio of ¹³⁴Cs/¹³⁷Cs (dated March 11, 2011) in the investigated particles was found to be 1.05 ± 0.01, which confirmed that the radiocaesium in CsMPs and in the contaminated soil particles has the same source of origin, which could be unite 3 of FDNPP.
... Areas further away from Chernobyl were also affected by relatively high levels of deposition due mostly to rainfall as the radioactive cloud passed over these areas (De Cort et al., 1998). Cesium is very soluble in water, but also is readily adsorbed by clay minerals (Cremers et al., 1988) and becomes irreversibly fixed to clay minerals over time (Absalom et al., 1995). Once 137 Cs reaches the soil surface, it is strongly and quickly adsorbed by the fine soil particles and is essentially nonexchangeable in most environments (Ritchie, 2004). ...
The objective of the present study was to investigate the natural isotopes in soil of Salah Aldeen Governorate, 200 km north Baghdad, Iraq and the possible contamination from 137 Cs and depleted uranium (DU). High-resolution gamma spectrometric system with a relative efficiency of 50% was employed for the measurement of 232 Th, 226 Ra, 40 K, and 137 Cs activity in the soil samples. The ratio 235 U/ 238 U was calculated to indicate the presence of DU and possible contamination. In general, all values of the natural isotopes are within the range of normal expectation found in soils. Activity concentration of 40 K exhibited higher values in the range 200 to 400 Bq/kg although these values seem lower than values reported in soils of other countries. Although the magnitudes of 137 Cs concentration were low as compared with natural isotopes, the range value was very wide. Based on 235 U/ 238 U ratio, it is evident that the investigated soil samples were none contaminated with depleted uranium.
... Abundance and selectivity of these FES in soil are frequently expressed in terms of the radiocaesium interception potential (RIP) Sweeck et al., 1990). In organic soils, RCs sorption on less selective sites in soil organic matter (SOM) predominates (Sawhney, 1972;Cremers et al., 1988;Absalom et al., 1995;Dumat et al., 2000;Staunton et al., 2002;Koarashi et al., 2012;Fuller et al., 2015). Consequently, RCs is generally more mobile and plant-available in organic pastureland soils than in mineral agricultural soils (Van Bergeijk et al., 1992;Sanchez et al., 1999;Fesenko et al., 2002;Kruyts and Delvaux, 2002;Beresford et al., 2007). ...
Numerous radioecological models have been developed to predict radionuclides transfer from contaminated soils to the food chain, which is an essential step in preparing and responding to nuclear emergencies. However, the lessons learned from applying these models to predict radiocaesium (RCs) soil-to-plant transfer following the Fukushima accident in 2011 renewed interest in RCs transfer modelling. To help guide and prioritise further research in relation to modelling RCs transfer in terrestrial environments, we reviewed existing models focussing on transfer to food crops and animal fodders.
To facilitate the review process, we categorised existing RCs soil-to-plant transfer models into empirical, semi-mechanistic and mechanistic, though several models cross the boundaries between these categories. The empirical approach predicts RCs transfer to plants based on total RCs concentration in soil and an empirical transfer factor. The semi-mechanistic approach takes into account the influence of soil characteristics such as clay and exchangeable potassium content on RCs transfer. It also uses ʻbioavailableʼ rather than total RCs in soil. The mechanistic approach considers the physical and chemical processes that control RCs distribution and uptake in soil-plant systems including transport in the root zone and root absorption kinetics.
Each of these modelling approaches has its advantages and disadvantages. The empirical approach is simple and requires two inputs, but it is often associated with considerably uncertainty due to the large variability in the transfer factor. The semi-mechanistic approach factorises more soil and plant parameters than the empirical approach; therefore, it is applicable to a wider range of environmental conditions. The mechanistic approach is instrumental in understanding RCs mobility and transfer in soil-plant systems; it also helps to identify influential soil and plant parameters. However, the comlexity and the large amount of specific parameters make this approach impractical for nuclear emergency preparedness and response purposes.
We propose that the semi-mechanistic approach is sufficiently robust and practical, hence more fit for the purpose of planning and responding to nuclear emergencies compared with the empirical and mechanistic approaches. We recommend further work to extend the applicability of the semi-mechanistic approach to a wide range of plants and soils.
... Input parameters are given in Table 5. The fixation rate f was calculated from experimental data on peat soils with different content of mica (Absalom et al., 1995). For the high-organic Lake Vorsee sediments, a soil with 0% mica was chosen; f was determined to be 2.0 d −1 from a graph of log (K d tot ) over time after contamination with 137 Cs. ...
In the shallow eutrophic Lake Vorsee with an organic-rich catchment the 137Cs activity concentration in water samples (n = 250) and different fish species (n = 631) was determined for a period of 30 years starting soon after the Chernobyl fallout. To understand the distribution and migration of 137Cs in the ecosystem of Lake Vorsee, also the 137Cs inventory in soils of the catchment area, in sediments, in suspended matter, in water plants, as well as its vertical distribution in soils and sediments were studied.
The time dependency of the 137Cs activity concentration in water and fish was modelled with a compartment model (AQUASCOPE) as well as with the sum of two exponential functions. Results for effective half-lives of 137Cs in water are
= 1.2 a and = 7.2 a; for small cyprinidae = 0.6 a and = 8.9 a; and for pike = 1.4 a and = 12.1 a. The vertical distribution of 137Cs activity concentration in soils was described by a partial differential equation (diffusion constant = (1.05 ± 1.16) cm2⋅a−1 and convection speed = (0.14 ± 0.07) cm⋅a−1) and its distribution in sediments by a system of two coupled partial differential equations (fixation rate f = 2.0 d−1; distribution coefficient = (543 ± 140) L⋅kg−1; sedimentation rate = (0.030 ± 0.010) g⋅(cm2⋅a)−1; bioturbation constant , decreasing linearly with depth with
= (3.3 ± 1.0) cm2⋅a−1 at the surface).
According to the extended AQUASCOPE model, the following fractions of the total 137Cs inventory were found in the different compartments of the lake ecosystem in 2016: 9.0⋅10−1 in soils of the catchment area, 1.0⋅10−1 in sediments, 5.5⋅10−5 in water, 1.5⋅10−5 in suspended matter, 1.3⋅10−5 in watermilfoil, and 1.6⋅10−6 in fish.
... • the most important factors that govern the cesium sorption on soil/clay are: mineralogical composition of the clay, the nature of clays (expanded, unexpanded exchange capacity) and the amount of the clayey fraction [2,[6][7][8][9]. Kamel and Navratil study [10], for example, shows that for the studied soil samples, 19 to 25% of the Cs + is found in the iron oxides fraction and 13-17% of the Cs + in the carbonates fraction [2,10]. ...
The paper presents experimental data on the testing of sequential leaching method of radionuclides from the soils contaminated during accidents or malfunctions of various nuclear installations. The leaching tests were performed for Cs-137 and Co-60 removing from the soil samples, using various chemical reagents (mineral acids, ammonium and potassium salts, acidified ammonium oxalate and hot water). The results obtained show the high efficiency of the method developed for Co-60 (96%) and 10% decontamination level for Cs-137. The aggressive reagents used were found generally unsuccessful for leaching of Cs-137 and thus, more advanced methods should be planned. The Cs+ sorption/desorption process is important for evaluation of the environmental risks associated with the radiocesium migration and the feasibility of remediation strategies.
... In addition, it was well known that the migration rate of 137 Cs slowed with time (e.g. Bossew and Kirchner, 2004;Rosén et al., 1999) because of the aging effect (e.g., Absalom et al., 1995;Roig et al., 2007). In the studied soil, the concentrations of exchangeable 137 Cs in 0-0.5 cm layer before the decontamination works (from second survey to sixth survey) were 766, 364, 329, 163 and 86 Bq kg −1 , and its percentage slightly decreased from 2.5, 2.4, 2.0, 2.2 to 1.8%, respectively. ...
After the Fukushima Dai-ichi Nuclear Power Plant accident on March 2011, continuous monitoring of the detailed vertical distribution of radiocesium in soil is required to evaluate the fate of radiocesium and establish strategies for remediation and management of the contaminated land. It is especially important to investigate paddy soil because little knowledge has been accumulated for paddy soil and wetland rice is a major staple in Japan. Therefore, we monitored the vertical distribution of 137Cs in abandoned paddy soil in a planned evacuation zone from June 2011 to March 2016. The decontamination works (i.e., 5 cm of surface soil removal and re-covering with uncontaminated soil) were conducted by the government in 2015. As a result of monitoring, the 137Cs gradually migrated downward with time and the 137Cs concentration in the 0-10 cm soil was almost homogenous in October 2014, although it was non-cultivated. The liner relationship was obtained between the median depth, which is the thickness of a soil layer containing half of the total 137Cs inventory, and the time after the accident, indicating the migration rate was constant (1.3 cm y-1) before the decontamination works. After the decontamination works, the 137Cs concentration in the uppermost surface layer was reduced by 90%, however the total 137Cs inventory was reduced by only 50-70%. It was shown that the efficiency of 137Cs removal by the decontamination works decrease linearly over time in fields like the studied paddy, in which the homogenization of 137Cs concentration occurred. Conversely, the downward migration of 137Cs to subsurface layers deeper than 10 cm (i.e., plowpan layer) with low permeability rarely occurred. It is expected that these unique trends in distribution and migration of 137Cs would be found in abandoned paddy soils with properties similar to the studied soil, sandy loam but poorly drained because of the low permeable plowpan layer, although further validation is necessary.
... Radiocaesium bioavailability is strongly influenced by soil properties (e.g. K status and clay content) (Absalom et al. 1995). Three soil parameters required to determine radioactive bioavailability in soils can be estimated. ...
The radioactivity of environmental samples from nuclear reactor sites must be analyzed before the public is given free access to the plants grown in these soils. Plant and corresponding soil samples were collected from a sample site around the Savar research reactor near Dhaka (Bangladesh) and the activity concentrations of natural radionuclides 226Ra (238U-chain), 228Ra (232Th-chain) and non-chained 40K were measured using gamma ray spectrometry. Soils of Savar contained more radioactive 40K than 226Ra and 228Ra. The influence of certain soil properties on the activity concentrations and transfer factors (TF) of natural radionuclides were investigated by correlating the observed data with those of soil properties. The activity concentrations of 40K were much higher than those of 226Ra and 228Ra in plants due to higher uptake from soils. The transfer factors for 226Ra, 228Ra and 40K were found to range from 0.04 to 0.10, 0.12 to 0.32, and 0.24 to 0.72, respectively. The soil to plant transfer factors for 40K was found to be much higher in plants, which might be due to this element being vital in plants. This study showed that activity concentrations of these radionuclides in plants and their plant transfer factors seem to depend on the activity concentrations of the same radionuclides in soil.
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... The plant parts that generally have the highest activity concentration of radionuclides are the husks of cereals and in the siliques of oil crops (Bengtsson et al. 2013). It has been found that radiocaesium is relatively mobile inside plant tissues; however, its availability for root uptake from clay-rich soils is low (Absalom et al. 1995(Absalom et al. , 2001Rosén 1996). This explains why direct contamination of agricultural crops, e.g. by radiocaesium, is an important pathway for the transfer of radionuclides from fallout to human food. ...
The contamination level in potato, oilseed rape and wheat in terms of
tubers, seeds and foliage has been investigated after the foliar application of
wet-deposited 134Cs and 85Sr at different growth stages in a microscale field
experiment conducted over consecutive years. The results indicate that the application
of radionuclides in the beginning of the growth season resulted in low 134Cs
and 85Sr activity in both seeds of wheat, oilseed rape and potato tubers across
sampling occasions. In the middle of the growth season during radionuclide fallout,
134Cs activity in potato tubers across sampling occasions was highest. The spraying
of radionuclides at later stages resulted in even lower 134Cs activity in potato tubers
but increased activity in seeds of wheat and oilseed rape.
... Mobility of radiocaesium decreases with time after its deposition in the soil due to an aging effect (Sanzharova et al., 1994;Absalom et al., 1995;Fesenko et al., 1997;Rigol et al., 1999;Roig et al., 2007;Takeda et al., 2009). A collapsing process of the interlayer space of phyllosilicates induces Cs fi xation onto soil (Hird et al., 1996). ...
... Sin embargo, para aquellos con vida media más larga son de mayor importancia como el Cesio ( 137 Cs) que proviene de experiencias nucleares. Por suerte, esta especia radioactiva es adsorbida por la fracción arcillosa, vermiculita, disminuyendo su disponibilidad (Absalom et al., 1995). ...
... Sin embargo, para aquellos con vida media más larga son de mayor importancia como el Cesio ( 137 Cs) que proviene de experiencias nucleares. Por suerte, esta especia radioactiva es adsorbida por la fracción arcillosa, vermiculita, disminuyendo su disponibilidad (Absalom et al, 1995) La radioactividad antropogénica se debe principalmente a los accidentes en centrales nucleares como los de Three Mile Island (1979), Chernobil (1986) y más recientemente Fukusima (2011). En segundo lugar, de las pruebas con bombas nucleares y las fugas radioactivas de reactores constituyen otra fuente importante de contaminación. ...
Introducción La solución del suelo es compartimiento del sistema suelo-planta que constituye el punto de encuentro de todos los procesos que intervienen tanto en la mejora de la fertilidad como en la degradación de los suelos cultivados. Ella provee el ambiente químico para las raíces de las plantas, de manera que definir las interrelaciones suelo – agua – planta en términos cuantitativos requiere de un conocimiento exacto de la química de la solución de suelo y de las leyes que la gobiernan. Los estudios de fertilidad de suelos y de la eficiencia de la fertilización se han basado en la determinación de la supuesta " disponibilidad " de nutrientes por diversos procedimientos rutinarios de extracción (Jackson, 1970). Pero, por lo general, los factores estructurales, hídricos y biológicos o son mal evaluados o sencillamente no tomados en cuenta por estos métodos rutinarios, por lo que la definición de fertilidad basada en estos criterios es bastante criticable. De manera que el panorama indicado por los métodos de laboratorio rutinarios sólo puede constituir aproximaciones cómodas para clasificar los suelos y algunos aspectos de su fertilidad potencial en un momento dado. Gracias a los progresos de las técnicas analíticas, en particular de la detección in situ de los elementos en los micro-sitios activos del suelo, nuevos avances se pueden realizar para valorizar mejor el compartimiento " solución de suelo " el cual puede ser una aproximación más exacta en el diagnóstico de la fertilidad actual y potencial. El primer paso que se tiene que dar para poder renovar el diagnóstico de la fertilidad es de tomar conciencia del valor relativo de las informaciones suministradas por los análisis de los laboratorios de rutina. El cambio constante de la composición de la solución de suelo en el tiempo y en el espacio hace que lo que importe no es tanto su composición exacta a un momento dado, sino los flujos de nutrientes que atraviesan este compartimiento. El segundo paso será entonces de analizar el funcionamiento del sistema planta-solución-suelo, privilegiando las estimaciones de flujos potenciales de nutrientes lo que supone el acceso a las características químicas, termodinámicas y cinéticas de los fenómenos en juego en este sistema. Definiciones de Solución de Suelo En realidad, la naturaleza de esta solución de suelo puede interpretarse desde diferentes puntos de vista, físico, químico, geológico y biológico. De hecho, las propiedades de esta solución han sido estudiadas por varias disciplinas científicas con diversos propósitos. Además de la propia ciencia del suelo y la agronomía, el estudio de la solución de suelo ha servido por igual a ecólogos, geoquímicos e hidrólogos. Desde un punto de vista simplista, la solución del suelo es un compartimiento químico (y biológico) transitorio para muchas especies químicas provenientes de la interacción con otras fases presentes en el suelo. Es un medio acuoso en el cual tienen lugar la gran mayoría de las
... Sin embargo, para aquellos con vida media más larga son de mayor importancia como el Cesio ( 137 Cs) que proviene de experiencias nucleares. Por suerte, esta especia radioactiva es adsorbida por la fracción arcillosa, vermiculita, disminuyendo su disponibilidad (Absalom et al., 1995). ...
INTRODUCCIÓN GENERAL
El presente “Apéndice Analítico”1 se ha ideado como apoyo científico y técnico para
profesionales como científicos, ingenieros, técnicos, profesores, estudiantes que, de una u otra
forma, se interesan en el diagnóstico de la fertilidad del suelo y en la eficiencia de la fertilización. En
el mismo, podrán encontrar unas discusiones críticas de los métodos de análisis de suelos más
utilizados en estas materias, para tener mejores elementos de juicio que permitan una interpretación
y aplicación racional y no dogmática de los resultados.
Al desarrollar sus capacidades críticas, tanto el analista como el responsable de la
interpretación de los resultados, tienen que conocer los alcances y los límites de la validez de estos
análisis, para orientar mejor a los productores en la racionalización de la producción agrícola. En la
consecución de este objetivo general se deben cumplir algunos objetivos específicos tales como:
‐ Seleccionar una serie de métodos de análisis accesibles a laboratorios modestos, dedicados
principalmente al diagnóstico de la fertilidad de suelos cultivados y al seguimiento de los
efectos del trabajo del suelo y de la fertilización.
‐ Poner a disposición del lector una bibliografía abundante que permita a los investigadores
tener acceso a métodos especializados, que se hacen indispensables para su campo
específico de investigación.
En la primera parte de este “Apéndice Analítico”, se presentan los métodos físicos de
fraccionamiento que incluye la granulometría y el fraccionamiento físico de la materia orgánica. El
lector encontrará una discusión detallada de la ley de Stokes de la sedimentación, con sus limitantes y
condiciones para su aplicación, así como los posibles errores que se pueden presentar. El
fraccionamiento cuantitativo de los constituyentes orgánicos puede mejorar sensiblemente la calidad
de los resultados analíticos y facilitar la interpretación de los procesos de mineralización, organización
y humificación del carbono y del nitrógeno.
En la segunda parte del Apéndice Analítico se presentan los métodos químicos, comenzando
con la determinación de pH del suelo y la determinación de los requerimientos de cal. Seguidamente
1 El presente Apéndice Analítico procede en gran parte de la obra de M. Pansu y J. Gautheyrou*, quienes dieron su permiso para
seleccionar y traducir elementos que pudieran ser de utilidad para completar esta obra de referencia sobre los suelos tropicales
cultivados. Igualmente, fueron tomados algunos procedimientos del cuaderno de análisis rutinario de suelo usado por los laboratorios del
INIA, elaborado por Julia Gilabert de Brito y Luis Nieves**, los cuales vienen a complementar la información presentada en la presente
obra. Expresamos nuestro agradecimiento por su apoyo.
* Marc Pansu et Jacques Gautheyrou, 2003 ‐ L’analyse du sol – minéralogique, organique et minérale. Springer, París, Berlín, Heidelberg,
New York, 995 p.
**Julia Gilabert de Brito y Luis Nieves 1990. Manual de Métodos Analíticos para caracterizar perfiles de suelos. CENIAP, Maracay, 101 p.
698
se describe el análisis elemental de C, H, N, tanto por vía húmeda como por vía seca o combustión.
Este tipo de análisis es importante en la caracterización y cuantificación de la materia orgánica,
elementos esenciales en el diagnóstico de la fertilidad potencial del suelo.
Otro de los parámetros importantes en la caracterización de los suelos, es el intercambio
iónico, por lo tanto, se presentan los métodos para la determinación de las capacidades de
intercambio tanto catiónico como aniónico, y la cuantificación de los nutrientes en su estado llamado
intercambiable al pH del suelo o a un pH estándar como el el pH 7 del buffer de acetato de amonio
normal.
Como es sabido, en el diagnóstico clásico de la fertilidad de suelos, la determinación de
nutrientes se realiza por procedimientos de extracción utilizando diversas soluciones de reactivos más
o menos agresivos, así como extractantes de diversa índole para cada nutriente o determinación. Este
modelo de diagnóstico basado en procedimientos de extracción específicos afecta la productividad de
los laboratorios y contribuye a aumentar los precios de los análisis. Ademas, estos procedimientos de
extracción específicos de cada elemento o grupo de elemento presenta inconvenientes no solamente
económicos sino también ecológicos, al aumentar indebidamente las cantidades de reactivos
agresivos o tóxicos.
En la tercera y última parte del Apéndice Analítico, se presenta una revisión bibliográfica sobre
las determinaciones que se pueden hacer a partir de la llamada “solución de suelo”, compartimiento
del sistema suelo‐planta que debería probablemente valorizarse más a futuro en el campo del
diagnóstico de la fertilidad y de los efectos de la fertilización. Ello permitiría desarrollar
procedimientos de extracción que usen menor cantidad de reactivos y que estos sean más amigables
con el ambiente. Además, las mejoras en sensibilidad y exactitud de los métodos modernos ofrecen
ahora límites de detección muy bajas para elementos solubles en el agua, con muestras de tamaño
muy reducido, permitiendo en algunos casos detecciones secuenciales o simultáneas de bajas
concentraciones de nutrientes.
Actualizar los métodos tradicionales mejoraría la eficiencia de los análisis de suelo,
disminuyendo el impacto ambiental de los reactivos evacuados en las aguas servidas de los
laboratorios. Esto es especialmente importante para estudios de modelización de los flujos de
nutrientes en el suelo, donde el seguimiento de la solución de suelo a lo largo de experimentos de
larga duración requiere numerosos análisis químicos.
Se acompaña la presentación de cada método de las consideraciones necesarias para un
análisis crítico de los resultados. En efecto, es primordial conservar un punto de vista científico a lo
largo de todo el proceso de diagnóstico de la fertilidad y los efectos de la fertilización. El proceso
científico comienza en el momento de la toma de las muestras in situ y se termina por la lectura y la
interpretación de los resultados. Los resultados deben luego interpretarse en función de un buen
conocimiento del proceso analítico utilizado, porque sólo son un reflejo más o menos deformado de
una realidad casi siempre compleja y cambiante. El científico reconstruye esta "realidad" según los
modelos más o menos conscientes procedente de su formación científica inicial y de su experiencia
profesional.
Es necesario recordar estas exigencias, ya que los primeros químicos que pusieron a punto la
mayoría de estos métodos de análisis de suelos, estaban, sobre todo, preocupados de obtener
resultados fiables y reproductibles en el laboratorio, en una época en la que los límites de detección
de los métodos analíticos eran mucho más elevados que ahora. Estos métodos clásicos reflejan en
gran parte el nivel de conocimientos de un pasado lejano, donde se usaban métodos de análisis
químicos poco sensibles.
... There is considerable variation in the soil to plant transfer of radionuclides. This is due to differences in pH, potassium status, clay and organic matter content (Absalom et al., 1995;Arapis and Perepelyatnikova, 1995;Sanzharova et al., 1996). ...
The primary aim of agrochemical countermeasures on radio-polluted lands is to reduce the radionuclide transfer into the human food chain. The productivity and uptake of 137 Cs and 90 Sr by spring wheat and red clover depending on potassium fertilizer rates and acidity of Podzoluvisol loamy sand soil were studied in field trials in Belarus. A balanced plant nutrition resulted both in the increase of red clover productivity and in the reduction of radionuclides concentration per unit of mass. The application of balanced fertilizer including 120 kg К 2 О per hectare in comparison with unfertilized control increased the productivity of spring wheat grain at pH 5.9 on 44% and pH 6.8 on 62% and red clover 58 and 72% respectively. The extent of 137 Cs and 90 Sr accumulation by spring wheat grain and clover differed significantly. Soil-to-plant transfer factors of radiocaesium and radiostrontium for spring wheat and red clover may be predicted based with consideration on pH tests of Podzoluvisol loamy sand soil. The optimization of soil reaction combined with application of balanced K fertilizer allowed the expansion of the area of spring wheat and clover cultivation on radio-polluted soils for production acceptable food and feedstuff.
... Knowledge about the cesium sorption in bog environment/on peat (e.g. Absalom et al., 1995) and cesium biosorption is however scarce (e.g. Sasaki et al., 2002). ...
... K d is the ratio of the concentration of radionuclide sorbed on a specified solid phase to the radionuclide concentration in a specified liquid phase [55]: (17) The K d approach takes no explicit account of sorption mechanisms but assumes that the radionuclide on the solid phase is in equilibrium with the radionuclide in solution and that exchange between these phases is reversible. However, the time elapsed since the incorporation of the radionuclide in the soil is known to affect the magnitude of K d , since a fraction of the incorporated radionuclide may become fixed by the solid phase (an aging effect related to sorption dynamics) [56,57]. K d values for specific radionuclides are commonly obtained from field and laboratory studies. ...
... For this study the two soil types were artificially contaminated by radiocaesium and the subsequent solution activity concentration measured over a three month period. Full details of the experimental methods used are given by Absalom et al (1995). The derived model parameters are given in table 11. ...
В условиях модельного вегетационного эксперимента установлены коэффициенты накопления (Кн) радионуклидов Cs–137 и Sr–90 для культуры салата (Lactuca sativa) для почв радиоактивно-загрязненных площадок Семипалатинского испытательного полигона (СИП). Диапазон варьирования полученных значений Кн на почвенных образцах с различных участков СИП для Cs–137 составил 2 порядка, для Sr–90 — 1 порядок. Методами непараметрического статистического анализа идентифи-цированы факторы, определяющие миграцию радионуклидов Cs–137и Sr–90 в системе «почва–растения» для почв СИП с различным характером радиоактивного загрязнения. Установлено, что значения Кн Cs–137 и Sr–90 напрямую зависят от содержания биодоступных форм изотопов, которое обусловлено характером проведенных испытаний. Полученные значения коэффициентов корреляции Кендалла показали полную функциональную зависимость (r=1, n=4, p<0,05) между параметрами накопления и содержанием биологически доступных форм радионуклидов Cs–137 и Sr–90 в почве с радиоактивно-загрязненных территорий полигона. Применение метода частной корреляции позволило установить факторы, определяющие в почве содержание доступных форм Cs–137 и Sr–90: для Cs–137 валовое содержание K (rxy-z = –0,81); для Sr–90 — валовое содержание Ca (r xy-z = –0,64). Полученные результаты раскрывают основные механизмы миграции радионуклидов Cs–137 и Sr–90 в системе «почва–растение», что имеет огромное практическое значение при проведении радиоэкологического мониторинга и планировании реабилитационных мероприятий на радиоактивно-загрязненных территориях СИП, а также на импактных территориях предприятий ядерно-топливного цикла, расположенных в аналогичных почвенно-климатических условиях.
This chapter aims to contribute to a comprehensive view of environmental radiobiology and discuss the effects of different kinds of ionizing radiation on ecosystems. The impact of ionizing radiation was considered on both organisms and the abiotic environment, assessing the fate of radionuclides in abiotic compartments (e.g., the movement through atmosphere, hydrosphere, and lithosphere) and in the trophic chains, with implications for human and non-human biota. The available methodologies for estimating radiation dose to biota were also addressed as well as the associated challenges. This chapter also focused on the impacts of ionizing radiation exposure on non-human biota from microorganisms to vertebrates, as well as on the basic concepts related to environmental radiobiology and the molecular effects associated with the exposure to different types of ionizing radiation. The particular context of Naturally Occurring Radioactive Material (NORM) contamination was also tackled, as well as its effects on non-human biota.
Surface contamination by bomb‐derived and Chernobyl‐derived ¹³⁷ Cs has been subject to changes due to physical decay and lateral transport of contaminated soil particles, which have resulted in an ongoing transfer of radionuclides from terrestrial ecosystems to surface water, river bed sediments, and flood plains. Knowledge of the different sources of spatial variation of ¹³⁷ Cs is particularly essential for estimating ¹³⁷ Cs transfer to fluvial systems and for successfully applying ¹³⁷ Cs as an environmental tracer in soil erosion studies. This study combined a straightforward sediment redistribution model and geostatistical interpolation of point samples of ¹³⁷ Cs activities in soil to distinguish the effects of sediment erosion and deposition from other sources of variation in ¹³⁷ Cs in the small Mochovce catchment in Slovakia. These other sources of variation could then be interpreted. Besides erosion and deposition processes, the initial pattern of ¹³⁷ Cs deposition, floodplain sedimentation, and short‐range spatial variation were identified as the major sources of spatial variation of the ¹³⁷ Cs inventory.
Under conditions of a simulated pot experiment in the case of salad (Lactuca sativa), quantitative parameters of Cs-137 and Sr-90 (Tf) accumulation by plants on soils from the former Semipalatinsk Test Site territory were obtained. The variation range of Tf values derived for soil samples from different STS areas was 2 orders of magnitude for Cs-137 and 1 order of magnitude for Sr-90. Using nonparametric statistical analytical techniques, determinants of the transfer of Cs-137 and Sr-90from soil to plants for STS soils with various natures of radioactive contamination were identified. The content of biologically available species of radionuclides has a significant effect on the accumulation of Cs-137 and Sr-90by salad. Values derived for Kendall correlation coefficients showed a complete functional dependence (r=1, n=4, p<0,05) between accumulation parameters and the content of biologically available species of Cs-137 and Sr-90in soil from radioactively contaminated test site areas. The use of partial correlation coefficients allowed identification of key soil contributors to the content of available speciation and, respectively, the accumulation of Cs-137 and Sr-90by the experimental crop: for 137Cs, the common content of K (rxy-z = -0,81); for Sr-90 — the common content of Ca (r xy-z = — 0,64). Findings reveal the main mechanisms of Cs-137 and Sr-90transfer from soil to plants, which are of great practical importance in the radio ecological monitoring and planning of rehabilitation measures taken in radioactively contaminated STS areas as well as in areas impacted by nuclear fuel cycle facilities (NFC) located under similar soil and climatic conditions.
Uncertainty and sensitivity analysis were conducted for a radioecological model which was developed and applied for severe accident scenario for Akkuyu NPP in Turkey. Uncertainty was investigated in the doses and activity concentrations. Sensitivity analysis was conducted to find out most influencing parameters on the doses. 96 parameters, related with foodstuffs, feedstuffs and grass, inhalation rate and reduction factor for external irradiation, and transfer of ¹³⁷ Cs, ¹³⁴ Cs and ¹³¹ I isotopes, were studied by probabilistic methods. Latin Hypercube Sampling method was used to generate random parameters. In sensitivity analysis Spearman rank coefficients between the parameters and doses were calculated. The uncertainty analysis proves that the lifetime doses are in the range of 4.8 - 32 mSv and short-term doses are in the range of 1.1 - 2.8 mSv when all parameters vary simultaneously. Sensitivity analysis proves that soil-plant and feed-cow milk transfer factors for cesium, beef and grain consumption, and reduction factor for external irradiation have more influence on the lifetime doses, and transfer factor for cow milk for iodine and interception factor for grass also affect the short-term doses.
In this chapter, the key aspects of agricultural radioecology on the territory of Ukraine, Belarus, and Russia, following the severe accident at the Chernobyl NPP, specifically, the iodine attack and population protection, the contamination of arable lands with long-lived radionuclides ⁹⁰Sr and ¹³⁷Cs, and their entry into the food chain, are considered. The factors governing the behavior of ⁹⁰Sr and ¹³⁷Cs in soil and their uptake by plants are examined in detail. A model has been proposed to study the behavior of ⁹⁰Sr and ¹³⁷Cs in the “soil–plant” system to identify the contamination of crops. Countermeasures for reducing the accumulation of radionuclides in crops and animal-derived food products are discussed, and an assessment of their effectiveness is provided.
The mobility of ¹³⁷Cs in soil decreases with time owing to fixation by micaceous minerals. Such ageing is a critical parameter for estimating and predicting annual change in ¹³⁷Cs contamination risk of agricultural products. The decrease in the exchangeable fraction of ¹³⁷Cs has traditionally been used as an index of the ¹³⁷Cs ageing. Under field conditions, however, exchangeable ¹³⁷Cs is influenced by several environmental factors. In this study, we propose a new index to evaluate the ¹³⁷Cs ageing with minimum influence of environmental factors. The ratio of the exchangeable ¹³⁷Cs fraction to exchangeable fraction of ¹³³Cs ((¹³⁷Cs/¹³³Cs)exch) eliminates the influence of environmental factors on exchangeable ¹³⁷Cs. We assessed the applicability of the (¹³⁷Cs/¹³³Cs)exch index, using a four-year field study of a rice paddy in allophanic Andosol, starting 200 days after the Fukushima Dai-ichi Nuclear Power Plant accident. The influence of K fertilization was also investigated. The ¹³⁷Cs and ¹³³Cs exchangeable fractions varied together, indicating that both were similarly controlled by environmental factors. The values of (¹³⁷Cs/¹³³Cs)exch decreased with time, reflecting ¹³⁷Cs fixation by the ageing. The half-time of the (¹³⁷Cs/¹³³Cs)exch decline was 6.6–17.7 years. Relative to K fertilization, the lack of K fertilization seemed to affect the ¹³⁷Cs ageing in two ways: the early ¹³⁷Cs fixation progressed more rapidly, probably because fewer competing K⁺ ions were present, and the long-term ageing process was occasionally hampered, probably by the release of reserve K from micaceous minerals. The (¹³⁷Cs/¹³³Cs)exch values were similar to the ratio of the ¹³⁷Cs to ¹³³Cs transfer factor of the rice straw. Thus, we conclude that the (¹³⁷Cs/¹³³Cs)exch index is reliable for evaluating the ¹³⁷Cs ageing, decrease in ¹³⁷Cs mobility caused by the diffusion into micaceous mineral interlayer, in the field.
We systematically investigated the sorption and fixation behaviors of radiocesium (¹³⁷Cs) for sediments taken from the rivers of Ukedo and Odaka around the Fukushima Daiichi Nuclear Power Plant. By comparing the Cs sorption and sequential desorption results at various Cs concentrations, across a range of sediment properties, we were able to understand the different contributions at frayed edge sites (FESs) and regular exchange sites (RESs) of the clay minerals, and their relationships with the Cs concentrations and the contents of organic matter (OM). The Cs sorption and fixation were dominated by FESs at trace Cs concentrations, and by ion exchange at RES and the collapse of interlayers at higher Cs concentrations. The Cs sorption at lower Cs concentration was strongly related to radiocesium interception potential (RIP); however, Cs fixation was more related to clay mineralogy (i.e. contents of mica, vermiculite and hydroxy-interlayered vermiculite) rather than the RIP. The first-order kinetic constants for time-dependent Cs sorption at low Cs concentrations were correlated negatively to the ratio between the total organic carbon and RIP values. This implies that Cs access to FESs requires a relatively long duration that is dependent on the contents of the OM. From these results, the sorption and fixation mechanisms were confirmed to be significantly different at different Cs concentrations. Then, the prediction of Cs transport should be based on the key mechanisms that are dominant at the actual trace levels of Cs. A significant difference between the Cs fixation behaviors at the Ukedo River and Odaka River may be understood by considering the differences in their clay mineralogy, due to the different geological settings and weathering stages of both catchments.
Organic amendments affect the behavior of radiocesium in soil-plant systems in a complex way; they can inhibit radiocesium fixation by clay minerals by blocking selective sorption sites, whereas K supplied to the soil solution by amendments can reduce Cs uptake by plant roots. Here, we investigated the influence of inorganic and organic amendments on the transferability of radiocesium from soil to grass seedling in a humus-rich Andosol with high exchangeable K content. Soil samples were spiked with a¹³⁷Cs tracer, treated with N, N–P–K, compost (cattle manure using rice straw), or no amendment (control soil), and subjected to repeated two-week wetting and air-drying treatments for one year in an artificial climate chamber. Small-scale cultivations of orchard grass were performed four times during the experimental period to assess temporal changes of availability of ¹³⁷Cs in the soils. The ¹³⁷Cs transfer factor (TF), defined as the ¹³⁷Cs concentration in the plant divided by that in the soil, decreased with time in the control soil. The soil treated with compost showed higher TFs than the control soil in each cultivation and a slower attenuation of ¹³⁷Cs transferability. By comparing the extractability of ¹³⁷Cs, NH4⁺, and K⁺ with the observed TFs, we show that K released from the compost was not effective in reducing root uptake of ¹³⁷Cs, but enhanced ¹³⁷Cs desorption from the soil under K-rich conditions. This result suggests that organic amendment is ineffective in reducing root uptake of radiocesium under high exchangeable K concentrations, and may instead enhance the long-term availability of radiocesium in soils.
Soil amendments with zeolite and vermiculite were expected to prevent radiocaesium (¹³⁷Cs) dissolution and uptake from the soil by plants. In this study, we investigated how zeolite and vermiculite added to soil influence the radiocaesium fixation with ageing. Zeolite and vermiculite were mixed with soil (1 wt%) before or after the addition of carrier-free caesium-137 (¹³⁷Cs) to soils with different radiocaesium interception potential (RIP), which is related to the capacity of the soil to fix trace radiocaesium. Then, the soils were exposed for repeated wet and dry cycles to accelerate ¹³⁷Cs immobilization, and its extractability by 1 mol L⁻¹ ammonium acetate was determined before and after 30 dry and wet cycles. Before accelerated ageing (i.e before dry and wet cycles), when ¹³⁷Cs was adsorbed on the soil before the addition of the amendments, the addition of zeolite and vermiculite caused a decrease in the amount of exchangeable ¹³⁷Cs in low-RIP soils but an increase in the amount of exchangeable ¹³⁷Cs in high-RIP soils. The amount of exchangeable ¹³⁷Cs was significantly decreased after accelerated ageing regardless of the application of amendments. However, radiocaesium fixation with accelerated ageing was partly inhibited by the addition of zeolite, regardless of the RIP values. The ¹³⁷Cs adsorbed on highly selective sites in zeolite is exchangeable by 1 mol L⁻¹ ammonium acetate. Thus, because a portion of the ¹³⁷Cs is selectively adsorbed on highly selective sites in zeolite, the redistribution of ¹³⁷Cs to frayed edge site followed by ageing-induced fixation was likely limited. However, when ¹³⁷Cs was adsorbed on the soil before the addition of the amendments, the addition of zeolite and vermiculite had little influence on the amount of exchangeable ¹³⁷Cs. In conclusion, the use of realistic doses of zeolite and vermiculite as agricultural amendments is not effective in enhancing the immobilization of radiocaesium in soil.
The speciation of radiocaesium forms in the soil horizons that determine its further behaviour in the environment was considered. The present-day equilibrium in radiocaesium migration processes demonstrates that 70–90 % of the radionuclide was retained in the fixed form in upper 5–20 cm soil layer regardless of the type of soil and nature of contamination. In the forest ecosystems the litter layer continues to be a major accumulator of radiocaesium and contains 40–80 % of 137Cs being the main biochemical barrier to its vertical and horizontal migration. It was shown that radiocaesium can be easily absorbed by plant roots from soil solution and translocated to the above-ground plant biomass. The main environmental factors responsible for the variability in radiocaesium uptake by higher plants from soil are described. The uptake of radiocaesuim by plant species of herbal-shrubby storey in forest ecosystems was considered. It was shown that various plant species reveal the differences in 137Cs uptake via significantly different rates of the radionuclide accumulation during their vegetation period.
To assess the environmental impact of radioactive contamination of different ecosystems, information on source terms, mobility, biological uptake, and associated effects is needed. However, naturally occurring and artificially produced radionuclides can be present in different physicochemical forms (ions, colloids, nanoparticles, pseudocolloids, particles) influencing the mobility and biological uptake. Following severe nuclear events associated with the nuclear weapon or fuel cycles, a major fraction of refractory radionuclides will be present as radioactive particles; radionuclides are also present as colloids or low molecular mass (LMM) ionic species in effluents from nuclear installations. Thus, the distribution of radionuclide species depends on the source and release scenarios. LMM radionuclide species are believed to be mobile and potentially bioavailable, while high molecular mass (HMM) species such as nanoparticles, colloids, polymers, and pseudocolloids are mobile in water. Radioactive particles are considered biologically inert, but can be retained in filtering organisms as well as in soils and sediments. If mobile species are present, ecosystem transfer is relatively fast, whereas the ecosystem transfer is delayed if particles are present. Owing to time-dependent transformation processes such as interactions of mobile and reactive radionuclide species with components in soils and sediments or particle weathering and subsequent remobilization of associated radionuclide species, the original distribution of radionuclides deposited in ecosystems will change over time. Therefore, information on radionuclide species released and deposited, as well as on time-dependent transformation processes influencing the distribution of radionuclide species, is essential for the assessment of the environmental impact and risk associated with radionuclide contamination. This article summarizes available speciation techniques that should be utilized within radioecology, including fractionation and solid-state speciation, to characterize radionuclide species in waters, soils, and sediments.
To assess the environmental impact of radioactive contamination of different ecosystems, information on source terms, mobility, biological uptake, and associated effects is needed. However, naturally occurring and artificially produced radionuclides can be present in different physicochemical forms (ions, colloids, nanoparticles, pseudocolloids, particles) influencing the mobility and biological uptake. Following severe nuclear events associated with the nuclear weapon or fuel cycles, a major fraction of refractory radionuclides will be present as radioactive particles; radionuclides are also present as colloids or low molecular mass (LMM) ionic species in effluents from nuclear installations. Thus, the distribution of radionuclide species depends on the source and release scenarios. LMM radionuclide species are believed to be mobile and potentially bioavailable, while high molecular mass (HMM) species such as nanoparticles, colloids, polymers, and pseudocolloids are mobile in water. Radioactive particles are considered biologically inert, but can be retained in filtering organisms as well as in soils and sediments. If mobile species are present, ecosystem transfer is relatively fast, whereas the ecosystem transfer is delayed if particles are present. Owing to time-dependent transformation processes such as interactions of mobile and reactive radionuclide species with components in soils and sediments or particle weathering and subsequent remobilization of associated radionuclide species, the original distribution of radionuclides deposited in ecosystems will change over time. Therefore, information on radionuclide species released and deposited, as well as on time-dependent transformation processes influencing the distribution of radionuclide species, is essential for the assessment of the environmental impact and risk associated with radionuclide contamination. This article summarizes available speciation techniques that should be utilized within radioecology, including fractionation and solid-state speciation, to characterize radionuclide species in waters, soils, and sediments.
Soil-to-plant transfer factors (TF) of radiocaesium-137 were estimated by considering soil properties of 51 provinces in Thailand, and by using the model of Absalom. According to our study, the Absalom model could estimate average TF values to be 0.0852 ± 0.0475. Compared with average measured TF values which was 0.1289 ± 0.0529, it was found that calculated TF values decreased with increasing pH, clay contents and exchangeable K+. The corresponding calculated TF values increased with increasing organic matter contents and NH4+ concentrations. Statistical analysis showed that Relative Euclidean Difference (RED) was 0.238, reliability index (k) was 0.661 and geometrically intuitive reliability index (kg) was 1.97, which confirmed that the Absalom model was reasonably accurate. Calculated TF values by the Absalom model were in good agreement with the measured ones. However, calculated TF values were found to be significantly different from the measured ones for some provinces in Thailand. The parameters used in the Absalom model needed to be modified to suitably match soil properties in Thailand.
The contamination level in potato, oilseed rape and wheat in terms of tubers, seeds and foliage has been investigated after the foliar application of wet-deposited 134Cs and 85Sr at different growth stages in a microscale field experiment conducted over consecutive years. The results indicate that the application of radionuclides in the beginning of the growth season resulted in low 134Cs and 85Sr activity in both seeds of wheat, oilseed rape and potato tubers across sampling occasions. In the middle of the growth season during radionuclide fallout, 134Cs activity in potato tubers across sampling occasions was highest. The spraying of radionuclides at later stages resulted in even lower 134Cs activity in potato tubers but increased activity in seeds of wheat and oilseed rape.
Value of radiocaesium 137 Cs as one of Risk Factors in beef meat is very important for human health. Beef meat (m. longissimus lumborum et thoracis) from Czech Pied cattle in two less-favoured areas located more then 500 meters above sea level (Bohemian Forest Bohemian and Moravian Highland) was dependent on Sex (decrease by female, increase by male, P<1.10 -6) and on area (P<1.10 -6). Value of radiocaesium 137 Cs in beef meat (= 0,42 Bq.kg -1 ; s x = 0,28) was less then food standard (600 Bq.kg -1). This observed result are responding to finding another authors and could be used for next more detailed research in optimal utilization of Czech Pied cattle in less-favoured areas.
The ion-exchange selectivity of cesium and rubidium ions is studied in illite clay, saturated with either calcium, strontium, barium, sodium or potassium ions. The cesium- and rubidium-exchange levels studied vary between 50% and vanishingly low values. It is shown that the equilibria can be described in terms of three kinds of sites--corresponding to 0.5%, 3%, and 96.5% of the exchange capacity--each of which shows a characteristic selectivity coefficient. The site representing 0.5% of the capacity exhibits an exceedingly high selectivity for cesium ions (33 and 40 kJ/equiv with respect to sodium and calcium ions) and discriminates strongly between cesium and rubidium (6kJ/equiv). The equilibria on this site are thermodynamically reversible, as shown from three kinds of evidence: (1) the Cs-Rb trace selectivity difference, obtained from the equilibria in Ca, Sr, and Ba clay, agrees with the value obtained in the Na or K clay; (2) the same result is obtained from direct Cs-Rb trace mixture selectivity studies in Sr and Na clay; (3) the K-Na selectivity difference for this site as calculated from trace Cs equilibria agrees with the result obtained from Rb equilibria (11kJ/equiv). Finally, it is shown that the driving force for the high selectivity on this site is exclusively enthalpic.
Experiments were conducted to study the influence of stable Cs and K on ; the reactions of tracer quantities of Cs¹³ⷠand Kâ´Â² in soils and clay ; minerals, using an equilibrium batch method. Tracer quantities of both Cs/sup ; 137/ and Kâ´Â² were strongly sorbed in soils and clay minerals. Cesium was ; more strongly sorbed than K. Since the initial trace quantities of carrier-free ; Cs¹³ⷠwere very strongly sorbed, the sequence of the addition of the tracer ; radioisotope in relation to the addition of stable Cs and K determined the level ; at which equilibrium was attained. The absolute amount of Cs and K sorption ; depended on the kind of clay mineral and soil. Cesium sorption relative to K was ; greater in Ca-clay than in H-Al-clay. The concentration of the stable Cs and K ; present was also an important factor. When the tracer Cs¹³ⷠwas diluted to ; a negligible fraction of the total Cs in solution, only a negligible fraction of ; Cs¹³ⷠwas sorbed. In equimolar mixtures of Cs and K, the sorption of Cs ; relative to K decreased as the ionic concentration increased. As a corollary to ; this effect, under conditions of low ionic concentration, stable Cs was much more ; effective than K in releasing Cs¹³ⷠfrom soils. In high concentraltions, ; however, K may be, in certain soils, as effective as stable Cs. (auth)
Shaking of water-soluble fulvic acid with Cu2+-montmorillonite at pH 2·5 increased the interlamellar spacing from 10·0 to 15·1 A. The spacings were measured at ≈ 0% relative humidity. The extent of interlayer adsorption decreased with increase in pH. Differential thermal analysis and thermogravimetric examinations showed that in addition to interlayer adsorption, fulvic acid was also retained on external clay surfaces. The FA was held so tightly by the Cu2+-clay that > 3 4 of the total amount adsorbed, including degradation products formed from it, resisted decomposition even when heated to 1000 °C. I.R. spectra showed that β-diketone groups in fulvic acid reacted with Cu2+ in or on the clay to form acetylacetonate-type chelates. Indications were obtained that the mechanism postulated for the FA-Cu2+-clay interaction may also apply to reactions between FA and montmorillonite saturated with other di- and trivalent metal ions. Reactions of FA in aqueous solutions with metal ions in the presence of clays differ from those in the absence of clay. Montmorillonite appears to affect the conformation of the fulvic acid polymer in a way that favours reactions between CO groups and metal ions, a type of reaction that has so far not been observed in aqueous solutions in the absence of clay.
Investigations concerning selective sorption and fixation of K and similar cations by clay minerals and soil clays and the mechanisms of these reactions are reviewed. In particular, recent observations on selective sorption of these ions in dilute solutions by weathered micas and vermiculite in relation to the interlayer structures are discussed in detail. Also, implications of the resistance to weathering of small mica particles to cation selectivity by soils are described. Despite the increased understanding of sorption and fixation reactions, the following aspects remain unclear.
First, the mechanism of the collapse of alternate layers in vermiculite on K or Cs sorption has not been unequivocally established. Second, factors that impart stability to the central core of mica particles so that K extraction becomes progressively difficult are not known. Third, inability of Ca or Mg ions to expand interlayers of Cs-saturated vermiculite in contrast to K-saturated vermiculite is not completely understood.
The persistent absence of immobilisation (fixation) of Chernobyl-derived radioactive caesium in soils of the upland areas of Britain has been attributed to their peaty nature and assumed lack of Cs-fixing clay minerals. In the present study of a number of the affected soils the Cs-fixing clay mineral illite was found to be present in all cases. However, the amount of illite, and possibly the total clay fraction, was reduced by hydrogen peroxide pretreatments, which are required to remove organic matter prior to mineralogical analysis, unless they were buffered at a value close to the natural pH of the soil.Determination of the total number of potential Cs-fixing sites, using a batch-equilibrium sorption method, was not possible for these acid organic soils, due to the occurrence of edge-interlayer trapping. To overcome this a new sequential sorption method was devised. The total number of potential Cs-fixing sites in the soils studied was found to exceed those present in lowland mineral soils. This may be due to a greater proportion of clay interlayer regions being in the expanded state in the organic soils compared to the mineral soils. It is noted, however, that although a soil may have the potential to fix Cs ions, conditions necessary for the realisation of this potential may not occur in the field.
The diffusion of K ⁴⁰ into the clay crystal lattice of an illite was studied at equilibrium concentrations comparable to those occurring under field conditions. Time of equilibration was extended over 16 months. The self‐diffusion constant was found as roughly 1–3 × 10 ‐23 cm ² sec ‐1 ; the equivalent depth of penetration during the period of investigation amounted to a few Angstroms only.
A study of the uptake of Co, Cs, and Sr by rye, garden peas, and soybeans showed that the amount of these elements harvested, as well as the concentration in the plants, varied with the nature of the soil colloid on which they were grown.
Illite, kaolinite, montmorillonite, peat (fibrous), peat (sedimentary), and Putnam clay were Ca‐saturated, mixed with nutrients and sand; and treated with known amounts of radioactive Co ⁶⁰ , Cs ¹³⁷ , and Sr ⁸⁵ . Cultures of rye, peas, and soybeans were started in sand‐nutrient solution mixtures, then transferred to the radioactive colloid‐sand‐nutrient mixture. After a period of growth, the plants were harvested, weighed and assayed for their content of radioactivity. A study of the adsorption of the nuclides by the colloids was made by the determination of the distribution coefficient of each radioactive nuclide as a trace amount in Ca‐saturated exchange systems in 0.01 M CaCl 2 solution.
The order of uptake of Co by the rye plants was highest on illite followed in order by kaolinite, Putnam clay, peat (sedimentary), montmorillonite, and peat (fibrous). The uptake of Cs by the rye plants was highest in the plants grown on (fibrous) peat (10.59% harvested), and lowest for the plants grown on Putnam clay (0.36% harvested). The uptake of Sr by the rye plants was highest for the plants grown on montmorillonite (2.08% harvested). The uptake of the nuclides by peas and soybeans followed closely that of rye.
Data obtained from the distribution coefficient studies of the elements for the exchangers after equilibration in 0.01 M CaCl 2 solution reveals more Co adsorbed by the peats than by the clays; a high adsorption of Cs by illite and Putnam clays; and small differences with Sr with exchangers other than kaolin. The adsorption of the three elements was lower for kaolin than for the other cation‐exchangers. The percentage of Co and Cs harvested by the plants was correlated with the reciprocal of the distribution coefficient.
The adsorption of a radioisotope of caesium, ¹³⁷ Cs, has been interpretation and ratio and solution measured on four soils with differing clay mineralogies. All measurements have been made using unwashed soils in suspensions shaken for 2 h at 20°C. The effects of concentration in potassium and caesium, the nature of the background electrolyte and the soil:solution ratio have been investigated. The results are expressed either as the distribution coefficient, K D or as Freundlich isotherms.
The distribution coefficient of each of the soils decreases markedly as the concentration of caesium increases. The adsorption properties of the soils are not determined by the dominant clay mineralogy alone. Adsorption is always lower in 0.01 m CaCl 2 solution than in water. The addition of potassium has relatively little effect on adsorption of trace amounts of caesium; however, K D decreases with increasing concentrations of stable caesium. The major reason for the dependence of K D on the soil: solution ratio is found to be the non‐linear adsorption isotherm; the influence of the varying compositions of the solution and exchange complex is minor.
The validity of the use of a single K D value as an indicator of adsorption capacity and the meaning of the relative values of the Freundlich parameters are considered. The implications of these findings for the use of radiotracers and the usefulness of K D as an indicator of bioavailability are discussed.
Two issues are addressed in this paper: (a) the partitioning of radiocaesium between the micaceous specific site pool and the reversible ion exchange pool in mineral soils characterized by relatively low contents of organic matter; (b) the presentation of a new methodology for measuring radiocaesium availability in soils. The partitioning of radiocaesium between specific sites and reversible ion exchange sites is predicted on the basis of soil characterization: specific sites and overall ion exchange capacity. It is predicted that, in mineral soils, only very small fractions of radiocaesium can be expected to be present in readily reversible ion exchange sites. Such predictions are confirmed by an experimental screening study on radiocaesium desorption in a sandy, loamy sand, loam and clay soil, using a variety of desorption agents. A new methodology is presented for measuring radiocaesium availability, using an infinite bath scenario. The method is illustrated by a series of radiocaesium desorption protocols on humic acid, a reference illite clay, a sand loam, loam and clay soil and a set of podzolic soils, including samples from the Chernobyl 30-km zone. It is demonstrated that the (Ca + Mg)/K ratio in soils may play a key role in accelerating the radiocaesium fixation process in the specific sites. The implications of the positive effect of a high CaMg status in the soil on its fixation potential are discussed in terms of the long-term effects of possible countermeasures.
Sorption and fixation of microquantities of Cs by six minerals, as affected by the saturating cations, were studied. Micas and vermiculite sorbed more Cs in the presence of Ca and similar divalent cations than in the presence of K and similar monovalent cations. Montmorillonite and kaolinite, on the other hand, sorbed more Cs in the presence of K than in the presence of Ca. While micas and vermiculite fixed large proportion of the Cs sorbed, mont‐morillonite and kaolinite did not fix significant amounts of Cs against replacement by neutral salts. Thus, whereas Cs‐sorption by montmorillonite and kaolinite appeared to be largely electrostatic, the sorption and fixation of Cs by micas and vermiculite was governed by the size and hydration, rather than valence, of the competing cation. Micas particularly exhibited a large fixation of Cs. It is suggested that the fixation of Cs by micas occurs at the crystal edges where Cs may replace K and thus become a part of the stable mica structure.
The fallout of radiocaesium after the Chernobyl accident has renewed interest in its environmental behaviour. How it behaves in soils and sediments is important, for example, for the modelling of radiocaesium transport and retention in soils, and transfer from soil to plants and hence into the food chain. The traditional approach is highly empirical and is based on the measurement of solid–liquid distribution coefficients (K
D values) and transfer factors. It is generally believed that radiocaesium retention in soils and sediments is due to the presence of a small number of highly selective sites. Neither their abundance nor their Cs-selectivity has been quantitatively determined. Here we report a new methodology which achieves such characterization. Previously studies of radio-caesium in soils have foundered because K
D values have been derived under conditions very different from those in situ. We show that in situ K
D values can be predicted from readily measurable soil properties, thus enabling information about the mobility of radiocaesium in soils to be reliably and easily obtained. These findings can be generally applied to a wide variety of soils.
Adsorption, desorption, and isotopic exchange experiments have been used to investigate the kinetics and reversibility of cesium sorption on illite. Trace concentrations of cesium were used and experimental conditions were kept close to those of many freshwater environments. Initial adsorption of cesium on illite was rapid but was followed by slower uptake processes with time scales of weeks to months. The uptake proceeded faster and reached much higher Kd values in a Ca2+ environment than in a K+ environment. The apparent reversibility of sorption was affected by both the slow sorption processes and the nature of the competing cation. The desorption equilibration patterns indicate that cesium is released from rapidly accessible sorption sites but that the slow forward reaction continues. On time scales relevant for modelling its transport and retention in aquatic systems, cesium shows partially irreversible behaviour. A mechanistic interpretation for the observed sorption and isotopic exchange behaviour is proposed whereby cesium migrates slowly to energetically favourable interlayer sites from which it is not easily released.
We characterized the organic matter associated with the fine clay fraction separated from the Ae horizon of a Typic Haplorthod, using chemical, infrared, carbon-13 nuclear magnetic resonance, and gas chromatographic-mass spectrometric methods. Infrared and 13C NMR spectra of the initial clay-organic complex showed the prominence of long-chain aliphatics. Extraction with 0.5 M NaOH removed substantial amounts of fulvic acid. n-Hexane and chloroform extracts contained n-alkanes, ranging from C16 to C35, long-chain alcohols, and more complex aliphatics. About half of the clay-associated organic matter consisted of humic materials; the other half was composed mainly of long-chain aliphatics. From the characteristics of the materials isolated and identified, it appears that the long-chain aliphatics have low mobilities in soils and that it is fulvic acid that is capable of penetrating clay interlayers. If aliphatics are present in clay interlayers, they have most likely been transported there by fulvic acid or other humic materials within which they are captured and that act as vehicles for the transport of hydrolphobics within soil profiles.
(C) Williams & Wilkins 1988. All Rights Reserved.
The nonexchangeable fixation of macro amounts of cesium in five soils ; appeared to be different in character from the corresponding fixation of ; potassium and ammonium. It was also concluded that the fixation of cesium-137 in ; soils in carrier-free amounts is an essentially different process from those ; predominant in the fixation of macro amounts of cesium, potassium, and ammonium. ; Experimental procedures are described and results are discussed. (C.H.);
By using x-ray diffractometry and 13C-NMR spectroscopy, in combination with chemical and heat pretreatments, we have found good evidence for the occurrence of interlayer clay-organic complexes in two New Zealand soils. Here, the clay mineral is a regularly interstratified mica-smectite, and the organic species is a humic substance with a polymethylene chain structure. The organic material in the complex is resistant to peroxidation and pyrophosphate extraction. It is also thermally stable, being extensively decomposed only after the complex is heated at 400[degrees]C. A combination of soil factors seems necessary for interlayer complex formation. This includes a smectitic clay mineralogy, an accumulation of organic matter associated with a low microbial activity, and a highly acid soil reaction.
(C) Williams & Wilkins 1986. All Rights Reserved.
Semiquantitative mineral analysis has been done by X-ray diffraction on the < 2 μ- and 2-20 μ-size fractions of approximately five hundred Recent deep-sea core samples from the Atlantic, Antarctic, western Indian Oceans, and adjacent seas. Relative abundances of montmorillonite, illite, kaolinite, chlorite, gibbsite, quartz, amphibole, clinoptilolite-heulandite(?), and pyrophyllite(?) were determined. Mixed-layer clay minerals, feldspars, and dolomite were also observed but not quantitatively evaluated. From the patterns of mineral distribution, the following conclusions appear warranted: Most Recent Atlantic Ocean deep-sea clay is detritus from the continents. The formation of minerals in situ on the ocean bottom is relatively unimportant in the Atlantic but may be significant in parts of the southwestern Indian Ocean. Mineralogical analysis of the fine fraction of Atlantic Ocean deep-sea sediments is a useful indicator of sediment provenance. Kaolinite, gibbsite, pyrophyllite, mixed-layer minerals, and chlorite contribute the most unequivocal provenance information because they have relatively restricted loci of continental origin. Topographic control over mineral distribution by the Mid-Atlantic Ridge in the North Atlantic Ocean precludes significant eolian transport by the jet stream and emphasizes the importance of transport to and within that part of the deep-sea by processes operative at or near the sediment-water interface. Transport of continent-derived sediment to the equatorial Atlantic is primarily by rivers draining from South America and by rivers and wind from Africa. The higher proportion of kaolinite and gibbsite in deep-sea sediments adjacent to small tropical South American rivers reflects a greater intensity of lateritic weathering than is observed near the mouths of the larger rivers. This may be explained by a greater variety of pedogenic conditions in the larger drainage basins, resulting in an assemblage with proportionately less lateritic material in the detritus transported by the larger rivers despite their quantitatively greater influence on deep-sea sediment accumulation. In the South Atlantic Ocean, the fine-fraction mineral assemblage of surface sediment in the Argentine Basin is sufficiently unlike that adjacent to the mouth of the Rio de la Plata to preclude it as a major Recent sediment source for that basin. The southern Argentine Continental Shelf, the Scotia Ridge, and the Weddell Sea arc mineralogically more likely immediate sources. Transport from the Weddell Sea by the Antarctic Bottom Water may be responsible for the northward transport of fine-fraction sediment along parts of the western South Atlantic as far north as the Equator.
Soaking for 7 d with 0.05 M NaCl resulted in less caesium being sorbed by bentonite and kaolinite, but more by illite, compared to soaking for 2 d prior to addition of Cs. Overall the amount of Cs sorbed by the three clays was in the order bentonite > illite > kaolinite. Addition of humic acid to the clays depressed the sorption of Cs by all three clays, with illite showing the greatest effect. Desorption of added Cs was not totally reversible. The presence of humic acid resulted in an enhanced desorption of Cs from bentonite and to a lesser extent kaolinite. This enhanced desorption in the presence of humic acid was not seen for illite. The order of Cs retention following desorption for both clay and clay/ humic-acid mixtures was illite > bentonite > kaolinite. A single Kd value could not describe the whole isotherm, but individual values were calculated at different Cs concentrations to cover the range of the isotherm. Kd values for desorption were higher than the corresponding Kd for sorption. For both sorption and desorption, the presence of humic acid resulted in lower Kd values than in its absence.
“Compulsive” exchange takes place between a barium-soil and magnesium sulphate solution because Ba2+ ions are removed from solution by precipitation of barium sulphate. This phenomenon provides a basis for the very convenient routine method for cation-exchange capacity determination in soils described here. An EDTA titration is used to measure the amount of magnesium exchanged from a standard solution by a Ba-soil, which enables the cation-exchange capacity to be calculated. Advantages of the method are its speed and that the sample does not have to be washed exhaustively, so avoiding possible hydrolysis. It compares favourably with standard A.O.A.C. procedure and is much more widely applicable. Soils rich in organic matter, e.g., peats, or with much calcium carbonate, can be handled without difficulty.
A systematic study has been carried out on the radiocaesium sorption properties of 25 soils (forest, peat) covering organic matter (OM) contents in the range of 10–97%. Predictions are made for radiocaesium partitioning between micaceous Frayed Edge Sites (FES) and regular exchange sites (RES) on the basis of specific radiocaesium interception potentials of the soil and overall exchange capacity. It is shown that for soils with a very high OM content (> 80%), significant fractions are present in a readily reversible form in the OM phase. In soils of low-medium OM content (< 40%), only a very minor fraction is present in the OM exchange complex. Experimental findings, based on a desorption screening with a variety of desorption agents are in agreement with these predictions. On the basis of a study of sorption kinetics, some additional tools are available for identifying problem soils. In cases of very high OM content, radiocaesium adsorption is completed within hours demonstrating the involvement of the OM sites. In soils for which interception occurs in the FES, sorption continues to proceed for periods of 2–3 weeks. In conclusion, some examples are presented on radiocaesium desorption using ion exchangers as radiocaesium sinks in promoting desorption. For a peaty soil, near quantitative desorption is accomplished. For forest soils with OM contents in a range of 10–40%, fixation levels of 30–50% are demonstrated.
The sorption behaviour of caesium in 19 different soils from various regions of Sweden and Libya was studied in batch experiments. All experiments were carried out in the presence of a supporting electrolyte (0.01 n CaCl2). The experimental treatments were varying concentrations of Cs+ from 0.03 to 0.767 meq/litre, and one level of K+ and NH4+, 100 meq/litre. The sorption behaviour of caesium was complex. The distribution coefficient, the Kd value, was strongly reduced after small additions of stable caesium. However, at increasing concentrations of stable caesium the effect became much less. Also, when potassium and ammonium were present in the experimental environment the caesium sorption capacity of the soils was reduced. It was also found that the clay content in the soils strongly influenced the sorption of caesium as shown by the Kd values. Some of the Libyan soils showed higher Kd values than the Swedish soils with similar clay content.The data available and the relationships found for the 19 soils were used in the development of simple mathematical models for prediction of transfer factors for caesium to wheat.
In order to compare the transfer factors of 137Cs deposited after the fallout from the Chernobyl accident with 137Cs from nuclear weapons testing, soil and vegetation samples have been collected from a semi-natural ecosystem in western Norway. For the 137Cs from Chernobyl, 85% is found in the upper 5 cm of soil, whereas most of the nuclear weapons test 137Cs is found between 3 and 12 cm in the soil profile. The transfer factors from soil to vegetation are calculated to be 0.41 +/- 0.07 m2 kg-1 for the nuclear weapons test 137Cs and 0.40 +/- 0.22 m2 kg-1 for Chernobyl 137Cs. Hence, the results show no significant difference between the two fallouts. The effective ecological half-life of 137Cs for this ecosystem is estimated to be between 10 and 20 years. Wash-out and binding effects seem to be of minor importance for the uptake.
Following the deposition of radiocaesium from the Chernobyl accident the movement and slaughter of sheep in upland areas of west Cumbria, Scotland and Wales was restricted. Studies on the radioecology of Cs-137 and Cs-134 have been conducted at a farm within the affected area of west Cumbria since July 1986. The radiocaesium activity of upland sheep was found to decline when they were brought on to the farms' enclosed pastures and rise when they were returned to the open fell, where the radiocaesium content of vegetation has remained higher than on the pastures. The Cs-137 activity concentration of mixed grassland vegetation samples from the fell has declined over the study period, whereas the Cs-137 activity of ewes whilst grazing on the fell was higher in summer of 1987 than in autumn 1986. A number of factors which may have contributed to this discrepancy were investigated and are discussed. It is suggested that husbandry changes would be effective in reducing the number of lambs leaving the restricted area with radiocaesium activities over the limit (1000 Bq/kg fresh weight Cs-134 + Cs-137) set by the United Kingdom authorities.
Following the burial of low-level wastes in nuclear waste repositories, the interactions of radionuclides with surrounding soil infiltrated by acid precipitation could cause radionuclide migration and transport into nearby wells. To evaluate this migration through organically rich soil in the unsaturated zone, we measured sorption and desorption distribution ratios (Rd) of 57Co, 85Sr and 137Cs onto peat at pH 4. Peat samples rich in organic C showed relatively higher sorption Rd values for 57Co and 85Sr compared to soil samples with less organic C. The sorption and desorption Rd values for these radionuclides are similar, indicating the reversibility of the sorption process. The measurements suggest the importance of organic complexes for the retention of these radionuclides at the pH range (pH 4), where hydrolysis of the metals is not important and sorption is expected to be low. Cesium-137, on the other hand, appears to be associated more strongly with inorganic components of the soil samples, with its Rd value significantly higher in the peat material containing less organic C. The 137Cs desorption Rd on the same peat sample is also comparable to the sorption Rd indicating equilibrium. Both the organic and inorganic components of peat are thus able to retard the migration of radionuclides which may be found in nuclear waste repositories. The design of such a repository may be improved using a peat barrier to restrict radionuclide migration.
The effectiveness of the local Conasauga shale for removing cesium from ; radioactive waste solutions is discussed. Illite, which is present in the shale, ; has a particularly high affinity for cesium. The importance of the c-axis ; dimension of the 2: 1 layer lattice clays was demonstrated by using synthetic ; micas and selected cation treatment. The beneficial role of potassium in the ; mica and illtte is primarily because this element can induce and maintain ; collapse of the c-axis. Ion exchange dimension tn predicting the cesinm sorption ; behavior of clays. The potassium treatment and oven-drying of clays followed by ; cesium sorption may be used to differentiate montmorillonite from vermiculite. ; The importance of the findings in terms of weathering and diagenetic processes ; involving clays ts discussed. (auth);
Chernobyl radio-caesium in an upland sheep farm ecosystem Extraction and chemical analysis of interstitial water from soils and rocks
- B J Howard
- N A Beresford
- D G Kinniburgh
- D L Miles
Howard, B.J. & Beresford, N.A. 1989. Chernobyl radio-caesium in an upland sheep farm ecosystem. British Veterinary Journal, 145, Kinniburgh, D.G. & Miles, D.L. 1983. Extraction and chemical analysis of interstitial water from soils and rocks. Environmental Science and Technology, 17, 362-368.
The sensitivity of upland soils to radiocesium contamination In: Transfer of Radionuclides in Natural and Semi-natural Environments Diffusion of potassium-40 into an illite during prolonged shaking
- A Cremers
- A Elsen
- E Valcke
- J Wauters
- F J Sandalls
- S L Gaudern
Cremers, A., Elsen, A., Valcke, E., Wauters, J., Sandalls, F. J. & Gaudern, S.L. 1990. The sensitivity of upland soils to radiocesium contamination. In: Transfer of Radionuclides in Natural and Semi-natural Environments (ed. G. Desmet, P. Nassimbeni & M. Belli), pp. 238-248. Elsevier Applied Science, London. De Haan, F.A.M., Bolt, G.H. & Pieters, B.G.M. 1965. Diffusion of potassium-40 into an illite during prolonged shaking. Soil Science Society of America Proceedings, 29, 528-530.
After Chernobyl: Science made too simple
- Wynne B.
Wynne, B. 1991. After Chernobyl: Science made too simple? New Scientist, 1753, 44-46.
Adsorption and desorption of 6oCo, 85Sr and 137Cs on soil humic acid The impact of extreme environmental conditions, as occurring in natural eco-systems, on the soil-to-plant transfer of radionuclides Soil colloids as a factor in the uptake of cobalt, cesium and strontium by plants
- E P Dunnigan
- C W Francis
- M J Frissel
- H Noordijk
- K E Van Bergeij
Dunnigan, E.P. & Francis, C.W. 1972. Adsorption and desorption of 6oCo, 85Sr and 137Cs on soil humic acid. Soil Science, 114, Frissel, M.J., Noordijk, H. & Van Bergeij, K.E. 1990. The impact of extreme environmental conditions, as occurring in natural eco-systems, on the soil-to-plant transfer of radionuclides. In: Transfer of Radionuclides in Natural and Semi-natural Environments (ed. G. Desmet, P. Nassimbeni and M. Belli), pp. 40-47. Elsevier Applied Science, London. Graham, E.R. & Killion, D.D. 1962. Soil colloids as a factor in the uptake of cobalt, cesium and strontium by plants. Soil Science Society of America Proceedings, 26, 545-547.
The environmental chemistry of radiocaesium and other nuclides
- D H Oughton
Oughton, D.H. 1989. The environmental chemistry of radiocaesium and other nuclides. PhD. Thesis. University of Manchester (Dept of Chemistry).