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)

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>

MONOLITH COLUMNS FOR STUDYING ORGANIC SOIL PROFILES

1986 ◽  
Vol 66 (4) ◽  
pp. 737-742
Author(s):  
J. A. MILLETTE ◽  
R. S. BROUGHTON
Keyword(s):  
Hydraulic Conductivity ◽  
Physical Properties ◽  
Bulk Density ◽  
Organic Soil ◽  
Saturated Hydraulic Conductivity ◽  
Fiber Content ◽  
Organic Soils ◽  
Soil Profiles ◽  
Sampling Procedures ◽  
Monolith Columns

Monolith column construction and sampling procedures were described for organic soil profiles and used to measure the variation with depth of saturated hydraulic conductivity, bulk density and fiber content. The top 0.30 m of the organic soil was more permeable, had a greater bulk density and had a greater fiber content than the soil layer between 0.60 and 0.90 m from the soil surface. These columns can be used for correlations studies between physical properties and studies of the dynamic nature of the physical properties of organic soils. Key words: Saturated hydraulic conductivity, bulk density, fiber content, organic soil, monolith columns

Fire-patterned vegetation and the development of organic soils in the lowland vegetation mosaics of south-west Tasmania

2011 ◽  
Vol 59 (2) ◽  
pp. 126 ◽  
Author(s):  
S. W. Wood ◽  
Q. Hua ◽  
D. M. J. S. Bowman
Keyword(s):  
Soil Depth ◽  
Isotope Composition ◽  
Organic Soil ◽  
Fire Frequency ◽  
Organic Soils ◽  
Soil Profiles ◽  
Radiocarbon Age ◽  
South West ◽  
Vegetation Boundary ◽  
Vegetation Mosaics

Two contrasting ecological models have been proposed for the forest–moorland vegetation mosaics of south-west Tasmania that stress different interactions between fire, soils, vegetation and the physical environment to produce either stable or dynamic vegetation patterns. We investigated aspects of these models by sampling organic soil profiles across vegetation mosaics to determine variation in soil depth, organic carbon (C) content, nutrient capital, stable C isotope composition (δ13C) and 14C radiocarbon age in two contrasting landscape settings. 14C basal ages of organic soils ranged from recent (<400 calibrated (cal.) years BP) to mid Holocene (~7200 cal. years BP), with a tendency for older soils to be from poorly drained moorlands and younger soils from the forest. The long-term net rate of C accumulation ranged from 2.7 to 19.2 gC m–2 year–1, which is low compared with northern hemisphere peatland systems. We found that δ13C in organic soil profiles cannot be used to infer Holocene vegetation boundary dynamics in these systems. We found a systematic decrease of phosphorus from rainforest through eucalypt to moorland, but estimated that phosphorus capital in moorland soils was still sufficient for the development of forest vegetation. Our results suggest that the characteristics of organic soils across the landscape are the result of interactions between not only vegetation and fire frequency, but also other factors such as drainage and topography.

THE ESTABLISHMENT OF SYNCHRONY BETWEEN SUBSURFACE LAYERS AND ESTIMATION OF OVERALL SUBSIDENCE OF CULTIVATED ORGANIC SOILS BY A PALYNOLOGICAL METHOD

1982 ◽  
Vol 62 (2) ◽  
pp. 427-431 ◽  
Author(s):  
S. P. MATHUR ◽  
M. P. LÉVESQUE ◽  
P. J. H. RICHARD
Keyword(s):  
Bimodal Distribution ◽  
Organic Soil ◽  
Tsuga Canadensis ◽  
Organic Soils ◽  
Soil Profiles ◽  
Subsurface Layers ◽  
Physical Changes ◽  
Cultivated Soils

Pollen profiles of Tsuga canadensis in a virgin and two cultivated areas of a bog revealed the bimodal distribution characterized by easily recognizable minima, thus establishing synchrony between specific layers of the three organic soil profiles. This knowledge allowed estimation of overall subsidence of the cultivated soils, and would facilitate comparisons between subsurface layers now determinable as synchronous. Such comparisons should help determine the extent and depth of temporal biochemical and physical changes in subsurface layers of cultivated organic soils.

scholarly journals On the Configuration and Initialization of a Large Scale Hydrological Land Surface Model to Represent Permafrost

2019 ◽  
Author(s):  
Mohamed E. Elshamy ◽  
Daniel Princz ◽  
Gonzalo Sapriza-Azuri ◽  
Al Pietroniro ◽  
Howard S. Wheater ◽  
...  
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Land Surface Model ◽  
Organic Soil ◽  
Organic Soils ◽  
Surface Model ◽  
Soil Profiles ◽  
Computationally Efficient ◽  
Deep Soil ◽  
Mackenzie River

Abstract. Permafrost is an important feature of cold regions hydrology, particularly in basins such as the Mackenzie River Basin (MRB), and needs to be properly represented in hydrological and land surface models (H-LSMs) built into existing Earth System models (ESM), especially under the unprecedented climate warming trends that have been observed. Higher rates of warming have been reported in high latitudes compared to the global average resulting in permafrost thaw with wide-ranging implications for hydrology and feedbacks to climate. The current generation of H-LSMs is being improved to simulate permafrost dynamics by allowing deep soil profiles and incorporating organic soils explicitly. Deeper soil profiles have larger hydraulic and thermal memories that require more effort to initialize. This study aims to devise a robust, yet computationally efficient, initialization and parameterization approach applicable to regions where data are scarce and simulations typically require large computational resources. The study further demonstrates an upscaling approach to inform large-scale ESM simulations based on the insights gained by modelling at small scales. We used permafrost observations from three sites along the Mackenzie River Valley spanning different permafrost classes to test the validity of the approach. Results show generally good performance in reproducing present-climate permafrost properties at the three sites. The results also emphasize the sensitivity of the simulations to the soil layering scheme used, the depth to bedrock and the organic soil properties.

scholarly journals On the configuration and initialization of a large-scale hydrological land surface model to represent permafrost

2020 ◽  
Vol 24 (1) ◽  
pp. 349-379 ◽  
Author(s):  
Mohamed E. Elshamy ◽  
Daniel Princz ◽  
Gonzalo Sapriza-Azuri ◽  
Mohamed S. Abdelhamed ◽  
Al Pietroniro ◽  
...  
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Land Surface Model ◽  
Organic Soil ◽  
Organic Soils ◽  
Surface Model ◽  
Soil Profiles ◽  
Computationally Efficient ◽  
Deep Soil ◽  
Mackenzie River

Abstract. Permafrost is an important feature of cold-region hydrology, particularly in river basins such as the Mackenzie River basin (MRB), and it needs to be properly represented in hydrological and land surface models (H-LSMs) built into existing Earth system models (ESMs), especially under the unprecedented climate warming trends that have been observed. Higher rates of warming have been reported in high latitudes compared to the global average, resulting in permafrost thaw with wide-ranging implications for hydrology and feedbacks to climate. The current generation of H-LSMs is being improved to simulate permafrost dynamics by allowing deep soil profiles and incorporating organic soils explicitly. Deeper soil profiles have larger hydraulic and thermal memories that require more effort to initialize. This study aims to devise a robust, yet computationally efficient, initialization and parameterization approach applicable to regions where data are scarce and simulations typically require large computational resources. The study further demonstrates an upscaling approach to inform large-scale ESM simulations based on the insights gained by modelling at small scales. We used permafrost observations from three sites along the Mackenzie River valley spanning different permafrost classes to test the validity of the approach. Results show generally good performance in reproducing present-climate permafrost properties at the three sites. The results also emphasize the sensitivity of the simulations to the soil layering scheme used, the depth to bedrock, and the organic soil properties.

RELATIONSHIPS BETWEEN SOME PROPERTIES OF ORGANIC SOILS FROM THE SOUTHERN CANADIAN SHIELD

1990 ◽  
Vol 70 (3) ◽  
pp. 363-377 ◽  
Author(s):  
D. ANN BROWN ◽  
S. P. MATHUR ◽  
ANTON BROWN ◽  
D. J. KUSHNER
Keyword(s):  
Principal Component Analysis ◽  
Acid Leaching ◽  
Principal Component ◽  
Organic Soil ◽  
Component Analysis ◽  
Soil Types ◽  
Organic Soils ◽  
Mining Districts ◽  
Two Populations ◽  
Inorganic Components

Different numerical methods used to distinguish between organic soil types are evaluated. The research was initiated by the suggestion that acid leaching from mining wastes could be prevented by capping the tailings with a self-renewing methane-producing muskeg bog, in order to prevent the penetration of oxygen to the wastes. Thirty organic soils from bogs in the mining districts of Elliot Lake, Sudbury, and Timmins, Ontario, and Noranda, Quebec, were sampled and 28 soil characteristics were measured. These characteristics, whose values are normally or lognormally distributed, were analyzed by several different statistical methods. Some characteristics indicate the existence of two populations, and others are bivariantly correlated. Canonical discriminant analysis was more successful than cluster analysis in separating the bogs into well-defined geographical groups. However, principal component analysis proved best at grouping the organic soils according to their organic and inorganic components, and we suggest that this is a suitable method for the general discrimination of organic soil types. Methane was present in all the 17 bogs tested for it, and in two very wet bogs more than 2 mmol of methane per liter were extracted. Key words: Muskeg bog, organic soils, soil characterization, principal component analysis

scholarly journals A Novel Approach to the Analysis of the Soil Consolidation Problem by Using Non-Classical Rheological Schemes

2021 ◽  
Vol 11 (5) ◽  
pp. 1980
Author(s):  
Kazimierz Józefiak ◽  
Artur Zbiciak ◽  
Karol Brzeziński ◽  
Maciej Maślakowski
Keyword(s):  
Constitutive Models ◽  
Organic Soil ◽  
Organic Soils ◽  
Soil Consolidation ◽  
Flexible Tool ◽  
One Dimensional ◽  
Novel Approach ◽  
Soil Skeleton ◽  
The One ◽  
The Relationship

The paper presents classical and non-classical rheological schemes used to formulate constitutive models of the one-dimensional consolidation problem. The authors paid special attention to the secondary consolidation effects in organic soils as well as the soil over-consolidation phenomenon. The systems of partial differential equations were formulated for every model and solved numerically to obtain settlement curves. Selected numerical results were compared with standard oedometer laboratory test data carried out by the authors on organic soil samples. Additionally, plasticity phenomenon and non-classical rheological elements were included in order to take into account soil over-consolidation behaviour in the one-dimensional settlement model. A new way of formulating constitutive equations for the soil skeleton and predicting the relationship between the effective stress and strain or void ratio was presented. Rheological structures provide a flexible tool for creating complex constitutive relationships of soil.

scholarly journals Interplay of riparian forest and groundwater in the hillslope hydrology of Sudanian West Africa (northern Benin)

2013 ◽  
Vol 17 (12) ◽  
pp. 5079-5096 ◽  
Author(s):  
A. Richard ◽  
S. Galle ◽  
M. Descloitres ◽  
J.-M. Cohard ◽  
J.-P. Vandervaere ◽  
...  
Keyword(s):  
West Africa ◽  
Transpiration Rate ◽  
Riparian Forest ◽  
Dry Season ◽  
Groundwater Table ◽  
Actual Evapotranspiration ◽  
Virtual Experiment ◽  
Deep Groundwater ◽  
Riparian Area ◽  
Study Results

Abstract. Forests are thought to play an important role in the regional dynamics of the West African monsoon, through their capacity to extract water from a permanent and deep groundwater table to the atmosphere even during the dry season. It should be the case for riparian forests too, as these streambank forests are key landscape elements in Sudanian West Africa. The interplay of riparian forest and groundwater in the local hydrodynamics was investigated, by quantifying their contribution to the water balance. Field observations from a comprehensively instrumented hillslope in northern Benin were used. Particular attention was paid to measurements of actual evapotranspiration, soil water and deep groundwater levels. A vertical 2-D hydrological modelling approach using the Hydrus software was used as a testing tool to understand the interactions between the riparian area and the groundwater. The model was calibrated and evaluated using a multi-criteria approach (reference simulation). A virtual experiment, including three other simulations, was designed (no forest, no groundwater, neither forest nor groundwater). The model correctly simulated the hydrodynamics of the hillslope regarding vadose zone dynamics, deep groundwater fluctuation and actual evapotranspiration dynamics. The virtual experiment showed that the riparian forest transpiration depleted the deep groundwater table level and disconnected it from the river, which is consistent with the observations. The riparian forest and the deep groundwater table actually form an interacting transpiration system: the high transpiration rate in the riparian area was shown to be due to the existence of the water table, supplied by downslope lateral water flows within the hillslope soil layer. The simulated riparian transpiration rate was practically steady all year long, around 7.6 mm d−1. This rate lies within high-end values of similar study results. The riparian forest as simulated here contributes to 37% of the annual hillslope transpiration, and reaches 57% in the dry season, whereas it only covers 5% of the hillslope area.

scholarly journals A fertile peatland forest does not constitute a major greenhouse gas sink

2013 ◽  
Vol 10 (11) ◽  
pp. 7739-7758 ◽  
Author(s):  
A. Meyer ◽  
L. Tarvainen ◽  
A. Nousratpour ◽  
R. G. Björk ◽  
M. Ernfors ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Eddy Covariance ◽  
Organic Matter Content ◽  
C Sequestration ◽  
Organic Soil ◽  
Organic Soils ◽  
Indirect Approach ◽  
Short Period ◽  
N2o Fluxes ◽  
C Assimilation

Abstract. Afforestation has been proposed as a strategy to mitigate the often high greenhouse gas (GHG) emissions from agricultural soils with high organic matter content. However, the carbon dioxide (CO2) and nitrous oxide (N2O) fluxes after afforestation can be considerable, depending predominantly on site drainage and nutrient availability. Studies on the full GHG budget of afforested organic soils are scarce and hampered by the uncertainties associated with methodology. In this study we determined the GHG budget of a spruce-dominated forest on a drained organic soil with an agricultural history. Two different approaches for determining the net ecosystem CO2 exchange (NEE) were applied, for the year 2008, one direct (eddy covariance) and the other indirect (analyzing the different components of the GHG budget), so that uncertainties in each method could be evaluated. The annual tree production in 2008 was 8.3 ± 3.9 t C ha−1 yr−1 due to the high levels of soil nutrients, the favorable climatic conditions and the fact that the forest was probably in its phase of maximum C assimilation or shortly past it. The N2O fluxes were determined by the closed-chamber technique and amounted to 0.9 ± 0.8 t Ceq ha−1 yr−1. According to the direct measurements from the eddy covariance technique, the site acts as a minor GHG sink of −1.2 ± 0.8 t Ceq ha−1 yr−1. This contrasts with the NEE estimate derived from the indirect approach which suggests that the site is a net GHG emitter of 0.6 ± 4.5 t Ceq ha−1 yr−1. Irrespective of the approach applied, the soil CO2 effluxes counter large amounts of the C sequestration by trees. Due to accumulated uncertainties involved in the indirect approach, the direct approach is considered the more reliable tool. As the rate of C sequestration will likely decrease with forest age, the site will probably become a GHG source once again as the trees do not compensate for the soil C and N losses. Also forests in younger age stages have been shown to have lower C assimilation rates; thus, the overall GHG sink potential of this afforested nutrient-rich organic soil is probably limited to the short period of maximum C assimilation.

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