Equilibrium and kinetic approaches for modelling sorption processes on radiocesium soil profiles in Fukushima prefecture

2020 ◽  
Author(s):  
Hamza Chaif ◽  
Frederic Coppin ◽  
Aya Bahi ◽  
Laurent Garcia-Sanchez
Keyword(s):  
Soil Contamination ◽  
Residence Time ◽  
Nuclear Power ◽  
Mineral Soil ◽  
Soil Surface ◽  
Organic Soils ◽  
Organic Layer ◽  
Soil Profiles ◽  
Sorption Model ◽  
Slow Evolution

<p>The study of radionuclides (RNs) retention processes onto the solid phases is a key element for the prediction of their transfer in soils. It allows a better quantification of the persistence of radioactive contaminants on the soil surface, their availability for root uptake and their vertical transfer towards groundwater.</p><p>This work addresses the comparison between equilibrium and kinetic hypotheses of sorption processes on real post-accidental soil contamination profiles. The equilibrium-kinetic (EK) sorption model was selected as a non-equilibrium parameterization embedding the K<sub>d</sub> approach. It supposes the existence of two types of sorption sites. The first sites are at equilibrium with solution, whereas for the second sites, kinetics of the sorption and desorption are taken into consideration.</p><p>We focused our study on four <sup>137</sup>Cs soil contamination profiles measured in a cedar stand 35 km northwest of the Fukushima Dai-ichi Nuclear Power Plant. Profiles were sampled at four different dates (between 2013 and 2018) by measuring <sup>137</sup>Cs activity in both organic (humus + litter layer) and mineral soil layers reaching a maximum depth of 20cm.</p><p>To successfully simulate the <sup>137</sup>Cs transfer throughout these soil profiles, the input flux at the mineral soil surface was reconstructed from monitored throughfall, stemflow and litterfall fluxes in the same forest stand from July 2011 to November 2016 crossed with initial deposit and dynamic of the organic layer activity.</p><p>The EK model reproduced the measured contamination profiles slightly better than the fitted K<sub>d</sub> model. While both models were able to reproduce the overall vertical distribution throughout the profiles, the persistent contamination at the surface was closer to the measured value with the EK approach. Additionally, the fitted K<sub>d</sub> parameters (2000 L/kg to 6500 L/kg depending on the parcel) were considerably higher than the recommended value by The IAEA for organic soils (270 L/kg). When used, this recommended K<sub>d</sub> value produced profiles with considerably faster transfer rate between layers and shorter persistence of the contamination at the surface.</p><p>To further distinguish the models behaviors, long term simulations were conducted. EK hypotheses induced much longer residence time of the contamination at the soil surface. For instance, by 2030, the EK approach predicted that 75 % of the contamination still remained in the 0-2 cm layer due to the slow desorption rate, whereas the K<sub>d</sub> approach predicted it to be around 51 %. This fraction becomes even smaller (8 %) when using the K<sub>d</sub> value (270 L/kg) recommended by the IAEA for organic soils.</p><p>These results prove that the choice of the sorption model is critical in post-accidental situations. An equilibrium approach, especially when using recommended parameter values, can result in an underestimation of the RNs residence time in the surface. Whereas a kinetic approach, by distinguishing different sorption and desorption rates, is able to reproduce the slow evolution of <sup>137</sup>Cs soil profiles with time that is already observed in the case of Chernobyl contaminated areas 30 years after the accident.</p>

scholarly journals New predictions of 137Cs dynamics in forests after the Fukushima nuclear accident

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shoji Hashimoto ◽  
Naohiro Imamura ◽  
Shinji Kaneko ◽  
Masabumi Komatsu ◽  
Toshiya Matsuura ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Activity Concentration ◽  
Model Updating ◽  
Mineral Soil ◽  
Soil Surface ◽  
Organic Layer ◽  
Observation Data ◽  
Activity Concentrations ◽  
Pine Trees ◽  
The Difference

AbstractMost of the area contaminated by the Fukushima Daiichi Nuclear Power Plant accident is covered by forest. In this paper, we updated model predictions of temporal changes in the 137Cs dynamics using the latest observation data and newly provided maps of the predicted 137Cs activity concentration for wood, which is the most commercially important part of the tree body. Overall, the previous prediction and latest observation data were in very good agreement. However, further validation revealed that the migration from the soil surface organic layer to the mineral soil was overestimated for evergreen needleleaf forests. The new prediction of the 137Cs inventory showed that although the 137Cs distribution within forests differed among forest types in the first 5 years, the difference diminished in the later phase. Besides, the prediction of the wood 137Cs activity concentrations reproduced the different trends of the 137Cs activity concentrations for cedar, oak, and pine trees. Our simulation suggests that the changes of the wood 137Cs activity concentration over time will slow down after 5–10 years. Although the model uncertainty should be considered and monitoring and model updating must continue, the study provides helpful information on the 137Cs dynamics within forest ecosystems and the changes in wood contamination.

Influence of non-equilibrium sorption on the vertical migration of 137Cs in forest mineral soils of Fukushima prefecture

2021 ◽  
Author(s):  
Hamza Chaif ◽  
Frederic Coppin ◽  
Aya Bahi ◽  
Laurent Garcia-Sanchez
Keyword(s):  
Vertical Migration ◽  
Half Life ◽  
Mineral Soil ◽  
Terrestrial Ecosystems ◽  
Organic Layer ◽  
Soil Profiles ◽  
Sorption Model ◽  
Equilibrium Sorption ◽  
Sorption Parameters ◽  
Non Equilibrium

<p>Vertical migration of radiocesium is a key issue in soils impacted by Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Among radioactive substances deposited on terrestrial ecosystems, <sup>134</sup>Cs (with half-life 2.07 years) and <sup>137</sup>Cs (with half-life 30.2 years) were dominant and have by far the most radiological significance.</p><p>This work investigates the importance of non-equilibrium sorption on the vertical migration of <sup>137</sup>Cs in field conditions. The equilibrium-kinetic (EK) sorption model was selected as a non-equilibrium parameterization embedding the K<sub>d</sub> approach. It supposes the existence of two types of sorption sites. The first sites are at equilibrium with solution; whereas for the second sites, kinetics of the sorption and desorption are taken into consideration.</p><p>We focused our study on four <sup>137</sup>Cs soil contamination plots measured in a young cedar stand situated around 35 km northwest of the FDNPP. Profiles were sampled at four different dates (2013, 2014, 2016, and 2018) by measuring <sup>137</sup>Cs activity in both organic (humus + litter layer) and mineral soil layers reaching a maximum depth of 20cm.</p><p>To successfully simulate the <sup>137</sup>Cs transfer throughout these soil profiles, the input flux at the top of the mineral soil surface was reconstructed from global monitoring data from the forest stand and a first-order compartment model for the organic layer.</p><p>Our results showed that the inclusion of non-equilibrium sorption slightly improves the realism of simulated <sup>137</sup>Cs profiles compared to the equilibrium hypothesis. While both models were able to reproduce the overall vertical distribution throughout the profiles, the persistent contamination at the surface was closer to the measured value with the EK approach. As a consequence, the K<sub>d</sub> model overestimated the contamination into deeper layers and therefore overestimated the migration velocity of <sup>137</sup>Cs. Fitted sorption parameters suggested a fast sorption kinetic (1 - 7 hours) and a pseudo-irreversible desorption rate (3.2 - 3.4 x 10<sup>6</sup> years), whereas equilibrium sorption (4.0 x 10<sup>-3</sup> L kg<sup>-1</sup> on average) only affected a negligible portion of <sup>137</sup>Cs inventory.</p><p>To further distinguish the models behaviors, short and long term simulations were conducted. By June 2011, EK parameters fitted on our plots realistically reproduced different profiles measured in the same forest study site. Predictive modeling of <sup>137</sup>Cs profiles in soil suggested a strong persistence of the surface <sup>137</sup>Cs contamination by 2030, with exponential profiles consistent with those reported after the Chernobyl accident.</p><p>These results prove that the choice of the sorption model is critical in post-accidental situations. An equilibrium approach can result in an underestimation of <sup>137</sup>Cs residence time in the surface. Whereas a kinetic approach, by distinguishing different sorption and desorption rates, is able to reproduce the slow evolution of <sup>137</sup>Cs soil profiles with time that is already observed in the case of Chernobyl contaminated areas 30 years after the accident. Non equilibrium sorption parameters can be partially inferred from in situ measurements. However, further experiments in controlled conditions are required to better estimate the sorption parameters and to identify the processes behind non-equilibrium sorption.</p>

scholarly journals The occurrence of distinct prismatic & plary structures in organic soil profiles.

1963 ◽  
Vol 11 (5) ◽  
pp. 418-421 ◽  
Author(s):  
F. Kuiper ◽  
S. Slager
Keyword(s):  
Organic Soil ◽  
Groundwater Table ◽  
Organic Soils ◽  
Organic Layer ◽  
Soil Profiles ◽  
Seepage Water ◽  
High Permeability ◽  
Deep Groundwater ◽  
Peat Horizon

Prisms & plates occurring in organic soils were correlated with a deep groundwater table associated with the vicinity of a brook draining the area, sufficient thickness of the organic layer to form an impermeable reduced peat horizon preventing seepage-water from rising in the profile, or Fe coatings on the peds promoting high permeability of the oxidized peat. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Molybdenum at German Norway spruce sites: contents and mobility

2000 ◽  
Vol 30 (7) ◽  
pp. 1034-1040 ◽  
Author(s):  
Friederike Lang ◽  
Martin Kaupenjohann
Keyword(s):  
Norway Spruce ◽  
Forest Soils ◽  
Forest Floor ◽  
Forest Ecosystems ◽  
Mineral Soil ◽  
Organic Layer ◽  
Soil Profiles ◽  
Nitrogen Turnover ◽  
Acid Forest Soils ◽  
Mineral Soils

Molybdenum plays an important role in the nitrogen turnover of ecosystems. However, very little is known about Mo availability in forest soils. We measured the oxalate-extractable Mo concentrations of acid forest soils, the Mo, nitrate, phosphate, and sulfate fluxes from the organic forest floor into the mineral soil using resin tubes and the Mo concentrations of the tree needles at 28 different Norway spruce (Picea abies (L.) Karst.) sites in southern Germany. The supply of oxalate-extractable Mo varied from 51 to 3400 g·ha-1, with the lowest values occurring in sandstone-derived soils (370 ± 212 g·ha-1; mean ± SD). Molybdenum concentrations of current-year needles were in the range of 5 to 48 ng·g-1. The Mo needle concentrations and oxalate-extractable Mo of soils did not correlate. However, Mo fluxes (6-60 g·ha-1·a-1) from the organic forest floor into the mineral soils were correlated to needle concentrations and to the NO3 fluxes. We conclude that Mo turnover within forest ecosystems is governed by Mo plant availability of mineral soils as well as by plant Mo uptake. In addition, Mo cycling strongly affects Mo distribution within soil profiles and Mo fluxes out of the organic layer.

scholarly journals Biochar Chemistry in a Weathered Tropical Soil: Kinetics of Phosphorus Sorption

Agriculture ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 295
Author(s):  
Marina Moura Morales ◽  
Nicholas Brian Comerford ◽  
Maurel Behling ◽  
Daniel Carneiro de Abreu ◽  
Iraê Amaral Guerrini
Keyword(s):  
Mineral Soil ◽  
Soil Surface ◽  
Kinetic Studies ◽  
Inorganic Phosphorus ◽  
Initial Reaction ◽  
Phosphorus Sorption ◽  
P Sorption ◽  
Published Research ◽  
Kinetics Of

The phosphorus (P) chemistry of biochar (BC)-amended soils is poorly understood. This statement is based on the lack of published research attempting a comprehensive characterization of biochar’s influence on P sorption. Therefore, this study addressed the kinetic limitations of these processes. This was accomplished using a fast pyrolysis biochar made from a mix of waste materials applied to a highly weathered Latossolo Vermelho distrofico (Oxisol) from São Paulo, Brazil. Standard method (batch method) was used. The sorption kinetic studies indicated that P sorption in both cases, soil (S) and soil-biochar (SBC), had a relatively fast initial reaction between 0 to 5 min. This may have happened because adding biochar to the soil decreased P sorption capacity compared to the mineral soil alone. Presumably, this is a result of: (i) Inorganic phosphorus desorbed from biochar was resorbed onto the mineral soil; (ii) charcoal particles physically covered P sorption locations on soil; or (iii) the pH increased when BC was added SBC and the soil surface became more negatively charged, thus increasing anion repulsion and decreasing P sorption.

Direct seeding of black spruce in northwestern Ontario: Seedbed relationships

1994 ◽  
Vol 70 (2) ◽  
pp. 151-158 ◽  
Author(s):  
R. L. Fleming ◽  
D. S. Mossa
Keyword(s):  
Seedling Establishment ◽  
Black Spruce ◽  
Mineral Soil ◽  
Soil Surface ◽  
Direct Seeding ◽  
First Year ◽  
Strongly Correlated ◽  
Seedling Mortality ◽  
Northwestern Ontario ◽  
Seedbed Preparation

A series of spot seeding experiments was set out on coarse-textured upland sites in northwestern Ontario to investigate how black spruce (Picea mariana [Mill.] B.S.P.) seedling establishment and growth could be improved by site selection and seedbed preparation. Virtually all germination occurred within the first growing season. Annual seedling mortality rates were greatest during the first year, then declined steadily and stabilized at low levels (<10%) after the third year. The highest fifth-year establishment ratios (seedlings/viable seed sown) were found on seedbeds derived from materials near the mineral soil/humus interface. On wetter sites (i.e., higher Soil Moisture Regimes) the best seedbeds occurred closer to the soil surface. Mean fifth year establishment ratios for the best seedbeds were 0.032 on moderately fresh to fresh sites, 0.146 on very fresh to moderately moist sites, and 0.082 on moist to very moist sites. On adjacent lowland sites, slow-growing, compact Sphagnum mosses had a mean establishment ratio of 0.179. Mean fifth-year seedling heights on upland sites ranged from 12 to 14 cm, and were not strongly correlated with site or seedbed type. Key words: direct seeding, black spruce, seedbed, seedling establishment, site type and germination

Interactions of surface drying and subsurface nutrients affecting plant growth on acidic soil profiles from an old pasture

1986 ◽  
Vol 26 (6) ◽  
pp. 681 ◽  
Author(s):  
A Pinkerton ◽  
JR Simpson
Keyword(s):  
Subsurface Layer ◽  
Acid Soils ◽  
Subterranean Clover ◽  
Soil Surface ◽  
Soil Profiles ◽  
Poor Growth ◽  
South Wales ◽  
Reconstituted Soil ◽  
Subsurface Layers ◽  
Surface Drying

Previous studies on soils from old pastures in southern New South Wales have demonstrated that nutrients have accumulated at the soil surface, but that the 40-100-mm depth layer in many profiles has become strongly acidic (e.g. pH 4.7), and high in extractable aluminium. Poor growth of subterranean clover has occurred on such soils during dry periods and may be associated with poor root growth in the acidic, nutrient-poor subsurface layers. Possible nutritional causes of these observations were investigated using reconstituted soil profiles. The root and shoot growth of subterranean clover, wheat, oats and lucerne were compared in unamended profiles and in profiles amended by applying nutrients or calcium carbonate (lime) to correct the more obvious deficiencies of the subsurface layers. Subterranean clover grew well as long as the surface soil remained moist, so that plants could utilise the nutrients potentially available within it. When the surface (0-40 mm) was allowed to dry but the subsurface layers remained moist, growth was poor unless phosphate was applied to the moist layer. Subsurface application of lime alone was ineffective. Nitrogen application increased clover growth in the presence of added phosphate or surface moisture, but nitrogen alone did little to alleviate the effects of surface drought. Wheat, and to a lesser extent oats, responded to subsurface lime when the surface was moist, and both responded to subsurface phosphate when the surface was dry. Lucerne responded to subsurface phosphate similarly to subterranean clover but the response was more than doubled in the presence of additional borate and lime. Lime without borate was not effective. When the surface was maintained moist, liming both the surface (0-40 mm) and subsurface layers improved the response over liming the subsurface layer only. The results suggest that declining fertility and productivity in old pastures developed on acid soils may not be rectified by liming alone, but that cultivation, ripping or drilling of phosphate, and in some cases addition of borate, may be required to improve the penetration of nutrients, particularly phosphorus, to greater depth.

GHG mitigation potential of agricultural management practises on mineral and organic soils

2021 ◽  
Author(s):  
Saara Lind ◽  
Marja Maljanen ◽  
Merja Myllys ◽  
Mari Räty ◽  
Sanna Kykkänen ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Agricultural Soils ◽  
Mineral Soil ◽  
Ghg Emissions ◽  
Grassland Management ◽  
Organic Soils ◽  
Carbon Dioxide Exchange ◽  
Ghg Mitigation ◽  
Nutrient Quality ◽  
Effect On Yield

&lt;p&gt;Agricultural soils are a significant source of greenhouse gas (GHG) emissions. To study these emissions, we are currently building three research platforms that consist of full eddy covariance instrumentation for determination of net ecosystem carbon dioxide exchange and fluxes of methane and nitrous oxide. These platforms will be completed with supporting weather, plant and soil data collection. Two of our platforms are sites on organic soils with a thick peat layer (&gt;60 cm) and the third one is on a mineral soil (silt loam). To study the role of the grassland management practises at these sites, we have initiated ORMINURMI-project. Here, we will characterise the effects of ground water table (high vs. low), crop renewal methods (autumn vs. summer) and plant species (tall fescue vs. red glover grass) on greenhouse gas budgets of grass production. Also effect on yield amount and nutrient quality will be determined. In this presentation, we will present the preliminary data collected at these research platforms and our plans for the use of these data in the coming years.&lt;/p&gt;

scholarly journals Effects of substrate availability and competing vegetation on natural regeneration of white spruce on logged boreal mixedwood sites

2018 ◽  
Vol 48 (4) ◽  
pp. 324-332 ◽  
Author(s):  
Nicola A. Kokkonen ◽  
S. Ellen Macdonald ◽  
Ian Curran ◽  
Simon M. Landhäusser ◽  
Victor J. Lieffers
Keyword(s):  
Picea Glauca ◽  
Natural Regeneration ◽  
Negative Impact ◽  
Mineral Soil ◽  
Soil Surface ◽  
White Spruce ◽  
Solid Wood ◽  
Seedling Mortality ◽  
Competing Vegetation ◽  
Survival And Growth

Given a seed source, the quality of available substrates is a key factor in determining the success of white spruce (Picea glauca (Moench) Voss) natural regeneration. We examined the influence of substrate and competing vegetation on survival and growth of natural regeneration of white spruce up to 4 years following harvesting in deciduous-dominated upland boreal mixedwood sites. Feather moss, thick soil surface organic layers, litter, and solid wood were poor substrates for establishment. Early successional mosses establishing on mineral soil, thin organics, and rotten wood were generally favourable microsites but were not highly available on postharvest sites. Mineral soil substrates were not as suitable as expected, likely because on a postlogged site, they are associated with unfavourable environmental characteristics (e.g., low nutrient availability, exposure). There was some evidence that survival and growth of seedlings were improved by surrounding vegetation in the first years, but heavy competing vegetation had a negative impact on older seedlings. Burial by aspen litter greatly increased seedling mortality, especially when combined with a brief period of submergence due to heavy spring snowmelt. The results provide insight into conditions under which natural regeneration could be an option for establishing white spruce following harvesting of deciduous-dominated boreal mixedwood forests.

scholarly journals Radioecological assessment of forage agricultural land in the southwestern areas of the Bryansk region based on a set of statistical models

2021 ◽  
Vol 30 (2) ◽  
pp. 38-49
Author(s):  
S.I. Spiridonov ◽  
◽  
V.V. Ivanov ◽  
I.E. Titov ◽  
V.E. Nushtaeva ◽  
...  
Keyword(s):  
Soil Contamination ◽  
Statistical Models ◽  
Agricultural Land ◽  
Sandy Loam ◽  
Probabilistic Approach ◽  
Point Of View ◽  
Content Standards ◽  
Organic Soils ◽  
137Cs Content ◽  
Wide Range

This paper presents a radioecological assessment of forage agricultural land in the southwestern districts of the Bryansk region based on data characterizing the variability of the radionuclides content in the soil. Concentration of 137Cs in forage was calculated taking into account the proba-bility distributions of 137Cs soil contamination density and the soil to plant transfer factor. The pro-cessing data of the radioecological survey has shown the soil contamination density with 137Cs of agricultural lands in the southwestern areas of the Bryansk region obeys a lognormal law. The authors have used statistical models and software modules for the radioecological assessment of forage lands. Risks of exceeding the 137Cs content standards in forage obtained on soils with different texture have been calculated. The limiting levels of contamination of pastures and hay-fields with 137Cs, ensuring compliance with the specified risks for forage, have been estimated. The lowest limiting soil contamination density is characteristic of organic soils, which can be con-sidered “critical” from the point of view of 137Cs intake into forage. The authors have predicted the time of remediation of forage lands in the southwestern districts of the Bryansk region in the ab-sence of protective measures based on a probabilistic approach. The time period during which the risk of forage contamination for sandy, sandy loam and clay loam soils will decrease to 10% varies for the areas under consideration in a wide range, not exceeding 64 years. It is concluded that it is advisable to substantiate the value of the acceptable risk of forage contamination, taking into account radiological and socio-economic aspects.

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