Risk evaluation of radionuclides contamination on soil and groundwater under different scenarios simulating by HYDRUS-1D

2021 ◽  
Author(s):  
Liu Wenxiang ◽  
Yu Hanqing ◽  
Lu Yang
Keyword(s):  
Water Content ◽  
Radioactive Contamination ◽  
Soil Depth ◽  
Residual Water ◽  
High Concentration ◽  
Predictive Values ◽  
Lysimeter Experiment ◽  
Farmland Soil ◽  
1D Model ◽  
Hydrus 1D

<p>A large number of radionuclides, produced by nuclear accidents or nuclear waste, may cause radioactive contamination in the agricultural and aquatic ecosystems. Under these circumstances, it is necessary to optimize the remediation of agricultural areas polluted by radionuclides using innovative monitoring and prediction techniques. To mitigate radioactive contamination in farmland soil and effectively protect groundwater, some measures should be taken against on field investigation, laboratory experiment and model prediction. In this study, the HYDRUS-1D model was used to simulate the vertical migration of <sup>137</sup>Cs and <sup>60</sup>Co in farmland soil in northern China calibrating by the soil lysimeter experiment, and the scenario simulations of <sup>137</sup>Cs and <sup>60</sup>Co migration were conducted under different radioactive levels. Results showed that the order of sensitivity in saturated water content (θ<sub>s</sub>), residual water content(θ<sub>r</sub>), saturated hydraulic conductivity(K<sub>s</sub>) and distribution coefficient (K<sub>d</sub>) applied in HYDRUS 1D model was K<sub>d</sub> > θ<sub>s</sub> > θ<sub>r</sub> >K<sub>s</sub>. The simulated concentrations ​​of <sup>137</sup>Cs and <sup>60</sup>Co in Brown soil and Aeolian sandy soil on day 175 and 355 were significantly positively correlated with the measured values​​ (r>0.90, p<0.01). The verification results showed that the predictive values on the 577<sup>th </sup>day were also significant positive correlated with the measured values ​​(r>0.90, p<0.01). The RMSE, CRM and NRMSE calculating by simulated and measured values ​​of <sup>137</sup>Cs and <sup>60</sup>Co in soil were very small, indicating that HYDRUS 1D can be used to simulate the migration of radionuclides in farmland soil. Scenarios simulation results revealed that radionuclides were concentrated in the surface layer within 5 cm, but the migration depth has exceed 10 cm soil depth, and even reaches up to 23.5 cm depth at high concentration level. The surface soil should be cleaned timely to protect groundwater with high level from radioactive contamination and further study should be done about horizontal transport and numerical simulation.</p>

scholarly journals Effects of Saline Solutions on the Desiccation Cracking and Shrinkage Behavior of Gaomiaozi Bentonite

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Long Tan ◽  
Penglin Zheng ◽  
Qingbing Liu
Keyword(s):  
Water Content ◽  
Saline Solution ◽  
Shrinkage Strain ◽  
Sample Surface ◽  
Water Evaporation ◽  
Gmz Bentonite ◽  
Residual Water ◽  
High Concentration ◽  
Desiccation Cracking ◽  
Saline Solutions

Bentonite, when used as buffer/backfill material in the deep disposal of high-level radioactive waste (HLW), could undergo desiccation shrinkage or even cracking due to the heat released from HLW, impairing the efficiency of the barrier system. Furthermore, in-service buffer materials are inevitably in contact with the groundwater, which sometimes contain high salt concentrations. The groundwater salinity may modify the properties of bentonite and hence affect the process of desiccation and its performance. To investigate this effect, in this study, a series of temperature-controlled desiccation tests was conducted on compacted specimens of Gaomiaozi (GMZ) bentonite preliminarily saturated with two different saline solutions (NaCl and CaCl2) at the concentration varying from 0.5 to 2.0 mol/L. The experimental results indicated that, as the concentration of saline solution increases, the initial saturated water content of bentonite decreases, whereas the residual water content at the completion of the desiccation test increases. The water evaporation rate is reduced for the specimens saturated with a high-concentration saline solution, and CaCl2 has a more significant influence on water evaporation than NaCl. The evolution of cracks on the sample surface during the desiccation process can be divided into four stages: crack growth, maintenance, closure, and stabilization; an increase in the salt concentration effectively inhibits crack development. It was shown that the infiltration of saline solutions alters the microstructure of bentonite by changing the arrangement of clay particles from a dispersed pattern to more aggregate state, which results in a decrease in shrinkage strain and shrinkage anisotropy.

scholarly journals Assessment of the Physically-Based Hydrus-1D Model for Simulating the Water Fluxes of a Mediterranean Cropping System

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1657 ◽  
Author(s):  
Domenico Ventrella ◽  
Mirko Castellini ◽  
Simone Di Prima ◽  
Pasquale Garofalo ◽  
Laurent Lassabatère
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Cropping Systems ◽  
Cropping System ◽  
Hydraulic Parameters ◽  
Water Fluxes ◽  
Physically Based ◽  
Van Genuchten Model ◽  
1D Model ◽  
Hydrus 1D

In a context characterized by a scarcity of water resources and a need for agriculture to cope the increase of food demand, it is of fundamental importance to increase the water use efficiency of cropping systems. This objective can be meet using several currently available software packages simulating water movements in the “soil–plant–atmosphere” continuum (SPAC). The goal of the paper is to discuss and optimize the strategy for implementing an effective simulation framework in order to describe the main soil water fluxes of a typical horticultural cropping system in Southern Italy based on drip-irrigated watermelon cultivation. The Hydrus-1D model was calibrated by optimizing the hydraulic parameters based on the comparison between simulated and measured soil water content values. Next, a sensitivity analysis of the hydraulic parameters of the Mualem–van Genuchten model was carried out. Hydryus-1D determined simulated soil water contents fairly well, with an average root mean square error below 9%. The main fluxes of the SPAC were confined in a restricted soil volume and were therefore well described by the one-dimensional model Hydrus-1D. Water content at saturation and the fitting parameters α and n were the parameters with the highest impact for describing the soil/plant water balance.

scholarly journals Irrigation with domestic wastewater: a multivariate analysis of main soil changes

2010 ◽  
Vol 34 (4) ◽  
pp. 1427-1434 ◽  
Author(s):  
Thomas Vincent Gloaguen ◽  
Roberta Alessandra Bruschi Gonçalves ◽  
Maria Cristina Forti ◽  
Yves Lucas ◽  
Célia Regina Montes
Keyword(s):  
Multivariate Analysis ◽  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Acidity ◽  
Soil Depth ◽  
Tap Water ◽  
Domestic Wastewater ◽  
Field Capacity ◽  
Residual Water ◽  
Agricultural Practice

Irrigation with treated domestic sewage wastewater (TSE) is an agricultural practice to reduce water requirements of agroecossystems and the nutrient load impact on freshwaters, but adverse effects on soil chemical (salinization, sodification, etc.) and soil physical properties (alteration in soil porosity and hydraulic conductivity, etc.) have been reported. This study aimed to define some relationships among these changes in an Oxisol using multivariate analysis. Corn (Zea mays L.) and sunflower (Helianthus annuus L.) were grown for two years, irrigated with TSE. The following soil properties were determined: Ca2+; Mg2+; Na+; K+ and H + Al contents, cationic exchangeable capacity (CEC), sum of bases (SB), base saturation (V), texture (sand, silt and clay), macro-, micro-, and cryptoporosity (V MA, V MI and V CRI), water content at soil saturation (θS) and at field capacity (θFC), residual water content (θR), soil bulk density (d s), water dispersed clay (WDC) and saturated hydraulic conductivity (K SAT). Factor analysis revealed the following six principal factors: Fine Porosity (composed of Na+; K+; WDC, θR, θRFC, and V CRI); Large Porosity (θS, d s, V MA, Vs); Soil CEC (Ca2+; Mg2+; CEC, SB, V); Soil Acidity (H + Al); and Soil Texture (factors 5 and 6). A dual pore structure appears clearly to the factors 1 and 2, with an apparent relationship between fine porosity and the monovalent cations Na+ and K+. The irrigation (with potable sodic tap water or sewage wastewater) only had a significant effect on Fine Porosity and Large Porosity factors, while factors 3 and 4 (Soil CEC and Soil Acidity) were correlated with soil depth. The main conclusion was a shift in pore distribution (large to fine pores) during irrigation with TSE, which induces an increase of water storage and reduces the capacity of drainage of salts.

scholarly journals Estimation of Iodine Leaching in Soil Amended with Organic and Inorganic Materials Using HYDRUS 1-D Model

2021 ◽  
Vol 13 (19) ◽  
pp. 10967
Author(s):  
Muhammad Mohiuddin ◽  
Jawad Ali ◽  
Megersa Kebede Leta ◽  
Muhammad Waseem ◽  
Muhammad Irshad ◽  
...  
Keyword(s):  
Preferential Flow ◽  
Soil Depth ◽  
Soil Column ◽  
Freundlich Isotherm ◽  
Iodine Content ◽  
Inorganic Materials ◽  
Soil Columns ◽  
Column Studies ◽  
1D Model ◽  
Hydrus 1D

This study investigated the ability of a HYDRUS 1D model for predicting the vertical distribution of potassium iodine (200 ppm) in soil columns after amendment with five different common remediation materials (gypsum, lime, fly ash, charcoal, and sawdust) at a rate of 2.5% (w/w), relative to an unamended control soil. Results showed that relative to the unamended soil, iodine leaching was decreased by all amendments but that the magnitude of the decreases varied with the soil amendment applied. Iodine content was highest in the upper layer of the soil columns and decreased progressively with soil depth. The model was evaluated via comparison of the model simulated values with measured values from the soil column studies. The results showed that the HYDRUS 1D model efficiency was near to 1, indicating the stimulated results near to the measured values. Therefore, this study showed that iodine leaching through a soil could be ascertained well using a HYDRUS 1D model. The model over predicted iodine leaching, results in a weak correspondence between the simulated and the measured results for iodine leaching. This suggests that the HYDRUS-1D model does not explain accurately different organic and inorganic amended soil and the preferential flow that occurs in these columns. This may be due to the fact that Freundlich isotherm, which is part of the transport equations, does not sufficiently describe the mechanism of iodine adsorption onto the soil particles. This study would help to select an amendment for an effective management strategy to reduce exogenous iodine losses from agro-ecosystems. This would also improve scientific understanding of iodine transport in soil profile.

scholarly journals Estimation of Iodine Leaching in Soil Amended with Organic and Inorganic Materials Using Hydrus 1-D Model

2021 ◽  
Author(s):  
Muhammad Mohiuddin ◽  
Jawad Ali ◽  
Megersa Kebede Leta ◽  
Muhammad Waseem ◽  
Muhammad Irshad ◽  
...  
Keyword(s):  
Preferential Flow ◽  
Soil Depth ◽  
Soil Column ◽  
Freundlich Isotherm ◽  
Iodine Content ◽  
Inorganic Materials ◽  
Soil Columns ◽  
Column Studies ◽  
1D Model ◽  
Hydrus 1D

This study investigated the ability of a HYDRUS 1D model for predicting the vertical distribution of potassium iodine (200 ppm) in soil columns after amendment with five different common remediation materials (gypsum, lime, fly ash, charcoal and sawdust) at a rate of 2.5% (w/w), relative to an unamended control soil. Results shows that relative to the unamended soil, iodine leaching was decreased by all amendments but that the magnitude of the decreases varied with the soil amendment applied. Iodine content was highest in the upper layer of the soil columns and decreased progressively with soil depth. The model was evaluated via comparison of the model simulated values with measured values from the soil column studies. The results showed that the HYDRUS 1D model efficiency was near to 1, indicating that the stimulated results were near to the measured values. Therefore, this study showed that iodine leaching through a soil could be ascertained well using a HYDRUS 1D model. The model over predicted iodine leaching, resulting to a weak correspondence between the simulated and the measured results for iodine leaching. This suggests that the HYDRUS-1D model does not explain accurately different organic and inorganic amended soil and the preferential flow that occurs in these columns. This may be due to the fact that Freundlich isotherm, which is part of the transport equations, does not sufficiently describe the mechanism of iodine adsorption onto the soil particles. This study would help to select amendments for an effective management strategy to reduce exogenous iodine losses from agro-ecosystems. This would also improve understanding of iodine transport in soil profile.

scholarly journals Response characteristics of soil moisture to rainfall for a single grass vegetation in the urban area A case of regional grassland in Yangzhou City

2021 ◽  
Author(s):  
Jinbai Huang ◽  
Jiawei Wen ◽  
Chaofan Zhu ◽  
Diwen Luo
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Infiltration Depth ◽  
Rainfall Events ◽  
Response Characteristics ◽  
Increase Rate ◽  
1D Model ◽  
Different Depths ◽  
Hydrus 1D

A regional grassland with Bermudagrass in Yangzhou City of China was adopted as the study location. Based on the analysis of the different rainfall events and soil water content data in the same periods, the response characteristics of infiltration to rainfall were revealed in a certain degree. The surface resistance parameters (rs) are calibrated according to the soil water content at the depths of a range for 0-30 cm and of the root layer (0-10 cm). Penman-Monteith (P-M) equation was adopted to estimated the hourly evapotranspiration (ET) over the Bermudagrass lawn of the soil layers for the depths of 0-30 cm (ET30) and 0-10 cm (ET10), respectively. Applicability of HYDRUS-1D model for simulating soil water content at different depths was validated. The results indicated that the infiltration depth generally varies with the rainfall event grade, and on the whole, the infiltration depth increases with the improvement of amount of rainfall; the response time for the soil water content in root layer is much shorter with the less soil water content in the topsoil (0-5.5 cm); the increase rate of soil water content raised with increasing of rainfall intensity in the state of unsaturation; ET10 accounts for about 78% of ET30, which demonstrates the water consumed by ET is mainly provided by the soil water in the root layer. the rationality of the results of different rainfall events and infiltration depth achieved by the analysis of the observed data were verified via numerical simulation using Hydrus-1D.

scholarly journals SURFACE RESIDUES: EFFECTS ON SOIL MOISTURE AND TEMPERATURE1

2021 ◽  
Vol 34 (4) ◽  
pp. 887-894
Author(s):  
GUSTAVO HADDAD SOUZA VIEIRA ◽  
ARILDO SEBASTIÃO SILVA ◽  
ARUN DILIPKUMAR JANI ◽  
LUSINERIO PREZOTTI ◽  
PAOLA ALFONSA VIEIRA LO MONACO
Keyword(s):  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Depth ◽  
Block Design ◽  
Soil Disturbance ◽  
Dry Season ◽  
Depth Range ◽  
Sunn Hemp

ABSTRACT This study aimed to determine how crop residue placement and composition would affect soil water content and temperature during the dry season in the central region of Espírito Santo state, Brazil. A 19-week field study was conducted from April to August 2017. A 2 x 4 factorial study with four replications was implemented using a randomized complete block design. Factors were soil management [conventional tillage (CT) and no soil disturbance (ND)] and residue amendment [maize (Zea mays L.), sunn hemp (Crotalaria juncea L.), a maize-sunn hemp mixture, and a no amendment control]. Soil water content and temperature were measured weekly at predetermined soil depth intervals. Soil water content was higher in ND plots amended with surface residues than under all other treatments in the 0 to 0.05 m depth range. All residue amendments in this range were equally effective in conserving soil water. Surface residues reduced soil temperature by up to 8.4 °C relative to the control in ND plots. Incorporating residue amendments by CT cancelled all temperature-moderating benefits provided by surface residues. These results indicate that surface residues from cereals, legumes, or cereal/legume mixtures are equally effective in conserving soil water and moderating soil temperature during the dry season. Additional research is needed to determine how improved soil environmental conditions, generated by surface residues, would affect nutrient acquisition and crop performance.

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