An Analytically Based Model for the Simultaneous Leaching-Chain Decay of Radionuclides from Contaminated Ground Surface Soil Layers

1997 ◽  
Vol 73 (6) ◽  
pp. 919-927
Author(s):  
Mark S. Jarzemba ◽  
Randall D. Manteufel
Keyword(s):  
Surface Soil ◽  
Ground Surface ◽  
Soil Layers ◽  
Chain Decay

scholarly journals Estimating Surface Soil Heat Flux in Permafrost Regions Using Remote Sensing-Based Models on the Northern Qinghai-Tibetan Plateau under Clear-Sky Conditions

2019 ◽  
Vol 11 (4) ◽  
pp. 416 ◽  
Author(s):  
Cheng Yang ◽  
Tonghua Wu ◽  
Jiemin Wang ◽  
Jimin Yao ◽  
Ren Li ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Land Surface ◽  
Surface Soil ◽  
Ground Surface ◽  
Soil Heat Flux ◽  
Parameterization Scheme ◽  
Clear Sky ◽  
Sky Conditions ◽  
Permafrost Regions

The ground surface soil heat flux (G0) quantifies the energy transfer between the atmosphere and the ground through the land surface. However; it is difficult to obtain the spatial distribution of G0 in permafrost regions because of the limitation of in situ observation and complication of ground surface conditions. This study aims at developing an improved G0 parameterization scheme applicable to permafrost regions of the Qinghai-Tibet Plateau under clear-sky conditions. We validated several existing remote sensing-based models to estimate G0 by analyzing in situ measurement data. Based on the validation of previous models on G0; we added the solar time angle to the G0 parameterization scheme; which considered the phase difference problem. The maximum values of RMSE and MAE between “measured G0” and simulated G0 using the improved parameterization scheme and in situ data were calculated to be 6.102 W/m2 and 5.382 W/m2; respectively. When the error of the remotely sensed land surface temperature is less than 1 K and the surface albedo measured is less than 0.02; the accuracy of estimates based on remote sensing data for G0 will be less than 5%. MODIS data (surface reflectance; land surface temperature; and emissivity) were used to calculate G0 in a 10 x 10 km region around Tanggula site; which is located in the continuous permafrost region with long-term records of meteorological and permafrost parameters. The results obtained by the improved scheme and MODIS data were consistent with the observation. This study enhances our understanding of the impacts of climate change on the ground thermal regime of permafrost and the land surface processes between atmosphere and ground surface in cold regions.

Seasonal and spatial variation of nitrogen dynamics in the litter and surface soil layers on a tropical dry evergreen forest slope

2010 ◽  
Vol 259 (8) ◽  
pp. 1502-1512 ◽  
Author(s):  
Naoyuki Yamashita ◽  
Seiichi Ohta ◽  
Hiroyuki Sase ◽  
Jesada Luangjame ◽  
Thiti Visaratana ◽  
...  
Keyword(s):  
Spatial Variation ◽  
Surface Soil ◽  
Nitrogen Dynamics ◽  
Evergreen Forest ◽  
Soil Layers ◽  
Dry Evergreen Forest ◽  
Tropical Dry Evergreen Forest

The effects of gypsum on macroporosity and crusting of two red duplex soils

Soil Research ◽  
1985 ◽  
Vol 23 (4) ◽  
pp. 467
Author(s):  
CJ Chartres ◽  
RSB Greene ◽  
GW Ford ◽  
P Rengasamy
Keyword(s):  
Surface Soil ◽  
Clay Mineralogy ◽  
Crust Formation ◽  
Thin Sections ◽  
Soil Layers ◽  
Photographic Images ◽  
Image Analyser ◽  
A Minor ◽  
Minor Improvement ◽  
Gypsum Application

The effects of gypsum on the physical properties of two red duplex soils in northern Victoria were investigated by assessing the relative abundance of macropores (diameters greater than 75 �m) in the 0-30 mm zone of their cultivated layers. Samples were collected in October 1983 from both fallow cropped and stubble cropped plots. Changes in soil porosity between untreated and gypsum-treated plots were measured on photographic images of thin-sections using a Quantimet 720 image analyser. The soils differed in their clay mineralogy, one being dominated by illite, the other by randomly interstratified material. The results indicate only a minor improvement due to gypsum application in the area of macropores in the soils dominant in illite and kaolinite, whereas in the soil with the higher proportion of randomly interstratified clay minerals the area of macropores approximately doubled on the stubble cropped site and also considerably increased on the fallow cropped site. Micromorphological observations indicated that, in the presence of gypsum, crust formation was reduced because less clay was mobilized and redistributed in the surface soil layers.

scholarly journals Numerical Evaluation of The Nonlinear Behavior of Soil-Pile Interaction Under The Effect of Coupled Static-Dynamic Loads

2021 ◽  
Author(s):  
Duaa Al-Jeznawi ◽  
ISMACAHYADI Mohamed Jais ◽  
Bushra S. Albusoda
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Ground Surface ◽  
Frictional Resistance ◽  
Saturated Soil ◽  
Shaking Table ◽  
Physical Models ◽  
Soil Layers

Abstract Liquefaction of saturated soil layers is one of the most common causes of structural failure during earthquakes. Liquefaction occurs as a result of increasing pore water pressure, whereby the rise in water pressure occurs due to unexpected change in stress state under short-term loading, i.e., shaking during an earthquake. Thus, general failure occurs when the soil softens and eliminates its stiffness against the uplift pressure from the stability of the subsurface structure. In this case, the condition of soil strata is considered undrained because there is not enough time for the excess pore water pressure to dissipate when a sudden load is applied. To represent the non-linear characteristics of saturated sand under seismic motions in Kobe and Ali Algharbi earthquakes, the computational model was simulated using the UBCSAND model. The current study was carried out by adopting three-dimensional-based finite element models that were evaluated by shaking table tests of a single pile model erected in the saturated soil layers. The experimental data were utilized to estimate the liquefaction and seismicity of soil deposits. According to the results obtained from the physical models and simulations, this proposed model accurately simulates the liquefaction phenomenon and soil-pile response. However, there are some differences between the experiment and the computational analyses. Nonetheless, the results showed good agreement with the general trend in terms of deformation, acceleration, and liquefaction ratio. Moreover, the displacement of liquefied soil around the pile was captured by the directions of vectors generated by numerical analysis, which resembled a worldwide circular flow pattern. The results revealed that during the dynamic excitation, increased pore water pressure and subsequent liquefaction caused a significant reduction in pile frictional resistance. Despite this, positive frictional resistance was noticed through the loose sand layer (near the ground surface) until the soil softened completely. It is worth mentioning that the pile exhibited excessive settlement which may attribute to the considerable reduction, in the end, bearing forces which in turn mobilizing extra end resistance.

scholarly journals Evaluation of dynamic ground characteristics and seismic microzoning

1984 ◽  
Vol 17 (1) ◽  
pp. 15-23
Author(s):  
Yoshikazu Kitagawa ◽  
Yutaka Matsushima
Keyword(s):  
Ground Surface ◽  
Analytical Investigation ◽  
Soil Layers ◽  
Seismic Microzoning ◽  
Magnification Factors ◽  
Short Period ◽  
Miyagi Prefecture ◽  
Maximum Earthquake ◽  
Penetration Tests ◽  
Microtremor Measurements

The maximum earthquake motions on the ground, the dynamic characteristics of soil-layers in the range of short period reflecting the shallow soil-layers on a small area are investigated, taking Sendai district damaged by the Off-Miyagi Prefecture Earthquake of June, 1978 as an example. The modeling of ground characteristics is performed based on the results of the analytical investigation of the elastic and inelastic system as well as microtremor measurements, boring data and penetration tests. In order to establish an appropriate seismic microzoning method with particular attention to the mathematical modeling, the predominant periods, magnification factors, maximum accelerations and velocities
on the ground surface and the ductility factors of super-structure are computed. The correlation between such seismic microzoning maps
and the extent of real damage to buildings is satisfactory.

scholarly journals Development of a Model for Predicting the Volatilization Flux from Unsaturated Soil Contaminated by Volatile Chemical Substances

2021 ◽  
Author(s):  
Monami Kondo ◽  
Yasuhide Sakamoto ◽  
Yoshishige Kawabe ◽  
Kengo Nakamura ◽  
Noriaki Watanabe ◽  
...  
Keyword(s):  
Unsaturated Soil ◽  
Surface Soil ◽  
Ground Surface ◽  
Weather Factors ◽  
Chemical Substances ◽  
Multi Phase Flow ◽  
Phase Liquid ◽  
Multi Phase ◽  
Adsorption Desorption ◽  
Unsaturated Condition

AbstractThis work developed a model for predicting the volatilization flux from the unsaturated soil contaminated by volatile chemical substances (VCSs) such as mercury and benzene. The model considers a series of phenomena under the unsaturated condition such as multi-phase flow consisting of a non-aqueous phase liquid, water, and gases together with the permeation of rainfall into the surface soil, the volatilization/condensation of VCSs, and the adsorption/desorption of VCSs. On this basis, this work clarified a mechanism for the generation of a volatilization flux at the ground surface. In addition, the effects of various transport phenomena in the surface soil on the magnitude and seasonal changes in this flux due to variations in weather factors such as rainfall level, temperature, and air pressure were quantitatively evaluated. This newly developed prediction model can be utilized to estimate dynamic variations in the flux under real-environmental conditions.

scholarly journals Assimilation of surface soil moisture into a multilayer soil model: design and evaluation at local scale

2014 ◽  
Vol 18 (2) ◽  
pp. 673-689 ◽  
Author(s):  
M. Parrens ◽  
J.-F. Mahfouf ◽  
A. L. Barbu ◽  
J.-C. Calvet
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Surface Soil ◽  
Soil Column ◽  
Cumulative Distribution ◽  
Surface Soil Moisture ◽  
Deep Soil ◽  
Background Error ◽  
Soil Layers ◽  
Diffusion Scheme

Abstract. Land surface models (LSM) have improved considerably in the last two decades. In this study, the Interactions between Surface, Biosphere, and Atmosphere (ISBA) LSM soil diffusion scheme is used (with 11 soil layers represented). A simplified extended Kalman filter (SEKF) allows ground observations of surface soil moisture (SSM) to be assimilated in the multilayer LSM in order to constrain deep soil moisture. In parallel, the same simulations are performed using the ISBA LSM with 2 soil layers (a thin surface layer and a bulk reservoir). Simulations are performed over a 3 yr period (2003–2005) for a bare soil field in southwestern France, at the SMOSREX (Surface Monitoring Of the Soil Reservoir Experiment) site. Analyzed soil moisture values correlate better with soil moisture observations when the ISBA LSM soil diffusion scheme is used. The Kalman gain is greater from the surface to 45 cm than below this limit. For dry periods, corrections introduced by the assimilation scheme mainly affect the first 15 cm of soil whereas weaker corrections impact the total soil column for wet periods. Such seasonal corrections cannot be described by the two-layer ISBA LSM. Sensitivity studies performed with the multilayer LSM show improved results when SSM (0–6 cm) is assimilated into the second layer (1–5 cm) than into the first layer (0–1 cm). The introduction of vertical correlations in the background error covariance matrix is also encouraging. Using a yearly cumulative distribution function (CDF)-matching scheme for bias correction instead of matching over the three years permits the seasonal variability of the soil moisture content to be better transcribed. An assimilation experiment has also been performed by forcing ISBA-DF (diffusion scheme) with a local forcing, setting precipitation to zero. This experiment shows the benefit of the SSM assimilation for correcting inaccurate atmospheric forcing.

Furrow irrigation of grain sorghum in a tropical environment. II. Influence of period of inundation on the utilization of soil and fertilizer nitrogen by the crop

1985 ◽  
Vol 36 (1) ◽  
pp. 83 ◽  
Author(s):  
GC Wright
Keyword(s):  
Nitrogen Uptake ◽  
Plant Uptake ◽  
Surface Soil ◽  
Grain Sorghum ◽  
Furrow Irrigation ◽  
Tropical Environment ◽  
Soil Layers ◽  
Fertilizer Nitrogen ◽  
Crop Maturity ◽  
Applied Nitrogen

Grain sorghum was grown in plots that had been fertilized, before sowing, with either 0, 80 or 170 kg Ha-1 nitrogen (N), and furrow irrigated for periods of 0 (sprinkler irrigated control), 3, 6, 12 or 24 h. The apparent uptake of fertilizer nitrogen declined from 63 to 7% as the period of inundation increased from 0 to 24 h. Large quantities of nitrate (up to 82 kg N ha-1) remained in the surface soil layers of all furrow irrigated ridges at crop maturity, in contrast to the sprinkler irrigated ridges (up to 4 kg N ha-1). At all inundation periods a constant proportion of the applied nitrogen was moved to the ridge tops, where it was unavailable for plant uptake. The differences in the recovery of applied nitrogen between the crops given 0 (sprinkler) and 3 h irrigation was mainly attributed to the surface accumulation of nitrate in the latter. Further reduction of nitrogen uptake with longer periods of inundation are attributed to differential rates of loss of nitrogen from the soil by denitrification and leaching.

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