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This mobility study aimed to determine the transport of TiO2 NPs from topsoil to deeper zones. The saturated soil column method imitated TiO2 NPs transport in real-world conditions and possible leaching scenarios. Three soils were studied: City soil (SCity), Agricultural (SAgri), and Sand. This investigation used ICP-OES, EDX, SEM and DLS to determine TiO2 NPs sizes, track the mobility patterns and quantify them in soil layers. The results have revealed that the mobility and retention of TiO2 NPs were highly influenced by Clay, organic matter (OM), and CEC. The concentration of TiO2 NPs in the deepest soil layers and the breakthrough water was low in SCity, in which Clay and OM were high. In contrast, TiO2 NPs were relatively high in the lowest layers of SAgri, where the Clay and OM content was insignificant. The columns packed with Sand showed the highest transported of TiO2 NPs where Clay and OM were absent. The breakthrough water obtained from Sand columns showed the highest TiO2 NPs concentration, followed by SAgri and SCity. The columns packed with SCity had more TiO2 NPs retention due to the presence of CEC in Clay and OM. This investigation showed that the transport of TiO2 NPs in the soil at low concentrations is a fact. It depends on soil properties such as texture, OM content, pH, and CEC. [ABSTRACT FROM AUTHOR]

This paper deals with the wave-induced cyclic response of a porous seabed (by means of oscillating parameters: pore-fluid pressure, soil displacement components, effective normal stress and shear stress components) due to a surface sinusoidal water-wave propagating over a seabed of infinite thickness. The main existing analytical solutions to the governing problem are critically discussed, pointing out their meaningful errors and doubtful items. A phase-lag phenomena is particularly studied as an immanent part of any complex-valued analytical solutions having a cyclic nature.

Coastal upland forests are facing widespread mortality as sea-level rise accelerates and precipitation and storm regimes change. The loss of coastal forests has significant implications for the coastal carbon cycle; yet, predicting mortality likelihood is difficult due to our limited understanding of disturbance impacts on coastal forests. The manipulative, ecosystem-scale Terrestrial Ecosystem Manipulation to Probe the Effects of Storm Treatments (TEMPEST) experiment addresses the potential for freshwater and estuarine-water disturbance events to alter tree function, species composition, and ecosystem processes in a deciduous coastal forest in MD, USA. The experiment uses a large-unit (2000 m2), un-replicated experimental design, with three 50 m × 40 m plots serving as control, freshwater, and estuarine-water treatments. Transient saturation (5 h) of the entire soil rooting zone (0–30 cm) across a 2000 m2 coastal forest was attained by delivering 300 m3 of water through a spatially distributed irrigation network at a rate just above the soil infiltration rate. Our water delivery approach also elevated the water table (typically ~ 2 m belowground) and achieved extensive, low-level inundation (~ 8 cm standing water). A TEMPEST simulation approximated a 15-cm rainfall event and based on historic records, was of comparable intensity to a 10-year storm for the area. This characterization was supported by showing that Hurricane Ida's (~ 5 cm rainfall) hydrologic impacts were shorter (40% lower duration) and less expansive (80% less coverage) than those generated through experimental manipulation. Future work will apply TEMPEST treatments to evaluate coastal forest resilience to changing hydrologic disturbance regimes and identify conditions that initiate ecosystem state transitions. [ABSTRACT FROM AUTHOR]

Aims: In the finite element method, the mechanical behaviour of plant roots has been modelled by solid element or embedded beam element (EBE). However, the former is computationally expensive, whereas the latter is unable to capture the root pull–out failure mode. In this study, we modified the constitutive stress–strain relationship of an existing EBE to calculate uprooting resistance by considering the root–soil interfacial shearing and the strength decline as root pulls out. Methods: We introduced an elasto–softening constitutive law to describe the root–soil interface interaction and an improved damage model to capture post–peak softening behaviour in EBE. We validated the EBE against three case studies. Finally, we conducted parametric analysis to study how root geometries, morphologies and soil saturation affect the uprooting response. Results: Our new model captures the pre–peak uprooting behaviour up to the peak pull–out force (Pul). Root systems that failed by pull–out mode always had lower Pul than those that failed by breaking, irrespective of the root morphology. Reduction of soil effective stress following soil saturation always reduced Pul and could change the root failure mode, depending on the anchorage length and root–soil contact surface area. Conclusions: Root–soil mechanical interaction and root failure mode, including pull–out and breakage, can now be modelled with more accuracy. We show the importance of considering soil moisture variation, which translates to variations in root reinforcement effects. The reinforcement effectiveness of deep–rooted systems can be halved, and the root failure mode can switch from breakage to pull–out, following soil saturation and reduction of soil effective stress. [ABSTRACT FROM AUTHOR]

The article provides the assessment of the levels of aerotechnogenic pollution caused by the emissions from stationary pollution sources of industrial agglomerations in Zhytomyr, taking into account climatic conditions that affect the dispersion and accumulation of pollutants in soils and vegetation cover of surrounding agricultural landscapes. The examination of dust accumulated on the surface of leaves showed that it contains high concentrations of Mn, Cr, Pb, Ni, and Cu. The bioindication method with the use of white-tip radishes was applied to estimate the extent of aerotechnogenic pollution. The results of the investigation testified to the high informativeness of the offered test objects. The indexes of soil saturation with heavy metals indicated the presence of intensive processes of their accumulation. As a consequence, this territory became unsuitable for agricultural production. The inhibition of growth of radish roots identified the toxicity level of the investigated technogenic substrates as medium and higher than average. Also, there is inverse close correlation relationship between the distance from the emission source and the soil phytotoxicity indicators in all the investigated directions.

Nanoscale zero valent iron (nZVI) is globally the main nanomaterial used in contaminated site remediation. This study aims to evaluate the sustainability of using nZVI in the nanoremediation of contaminated sites and to determine the factors that affect the sustainability of the use of nZVI in remediation. Five case studies of nZVI use on a pilot scale were selected. Life cycle analysis tools were used to evaluate environmental, economic, social impacts, and sustainability. The functional unit of the life cycle analyses was 1.00 m3 of remediated soil and groundwater. Case study of Brazil was the least sustainable, while case study of United States was the most sustainable. Only the modification of the functional unit results in variations in the sustainability index. Different factors influence the sustainability of nZVI in remediation, the main factor being the amount of nZVI used in the processes. Finally, this work contributes significantly to the state-of-the-art sustainable use of nZVI in remediation. This is a pioneering study in the detailed and comprehensive assessment of the sustainability of the use of nZVI in remediation. Through the analysis of case studies, it is possible to determine the main factors that influence the sustainability of the nZVI remediation life cycle. [Display omitted] • Life cycle sustainability of nano scale zero valent iron (nZVI) in soil remediation. • Groundwater remediation with nZVI is more sustainable. • Unsaturated soils remediation with nZVI requires more amount of nZVI. • Amount of nZVI used in remediation affects sustainability. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Agricultura Irrigada - RBAI is the property of Revista Brasileira de Agricultura Irrigada - RBAI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Very little is known about the impact of flooding and ground saturation on ectomycorrhizal fungi (EcM) and increasing flood events are expected with predicted climate change. To explore this, seedlings inoculated with the EcM species Tuber aestivum were exposed to a range of flood durations. Oak seedlings inoculated with T. aestivum were submerged for between 7 and 65 days. After a minimum of 114-day recovery, seedling growth measurements were recorded, and root systems were destructively sampled to measure the number of existing mycorrhizae in different zones. Number of mycorrhizae did not display correlation with seedling growth measurements. Seven days of submersion resulted in a significant reduction in mycorrhizae numbers and numbers reduced most drastically in the upper zones. Increases in duration of submersion further impacted mycorrhizae numbers in the lowest soil zone only. T. aestivum mycorrhizae can survive flood durations of at least 65 days. After flooding, mycorrhizae occur in higher numbers in the lowest soil zone, suggesting a mix of resilience and recovery. The results will aid in furthering our understanding of EcM but also may aid in conservation initiatives as well as providing insight for those whose livelihoods revolve around the collection of EcM fruiting bodies or cropping of the plant partners. [ABSTRACT FROM AUTHOR]

The Minimal Advanced Treatments of Surface Interaction and RunOff (MATSIRO), which has been used as a land-surface scheme in the global climate model, the Model for Interdisciplinary Research on Climate (MIROC), calculates Dunne runoff and base runoff using the TOPography-based MODEL (TOPMODEL). In past experiments that used MATSIRO, the runoff and its response to precipitation were too low compared to observation. We conjectured that those biases could be attributed to the water table's excessive depth. Its depth was diagnosed based on grid-mean soil moisture using a saturation threshold that was originally set to almost equal the porosity. In this study, sensitivity experiments, in which the threshold was decreased to 75, 50, 25, and less than 13 % of the porosity, were conducted, and the subsequent effects on river flow were investigated in the Chao Phraya River basin, Thailand, as a case study. As a result, both Dunne and base runoff increased along with the response of river flow to precipitation. The simulated river flow matched observations most closely with a threshold of 50 % saturation. In addition, soil moisture and the Bowen ratio changed significantly with the runoff changes induced by the threshold changes. These results suggested the importance of the relationship between grid-mean soil moisture and groundwater level for the TOPMODEL. Preliminary global experiments indicate that runoff sensitivity might be dependent on climate zone. [ABSTRACT FROM AUTHOR]

The calculation process of the traditional test method of unsaturated clay permeability coefficient is complicated, so a prediction model of unsaturated clay permeability is established. The e-lnp curve is drawn through K0 consolidation test of unsaturated remolded clay. The linear relationship between state variables and soil saturation was found, and the influence of unsaturated clay on soil properties was obtained. According to the adsorption storage mechanism and the position of soil compactness in the coordinate system, the characteristic curve of soil moisture and the prediction model of unsaturated clay permeability were established. The permeability test of unsaturated remolded clay is carried out by using transient profile method, and the results show that the model can well describe the change of permeability of unsaturated clay. [ABSTRACT FROM AUTHOR]

Hydrometeorological compound events cause severe economical, societal and environmental damage, but their investigation is difficult as they occur rarely and are multivariate. Here we use 50 high-resolution climate simulations from the single model initial condition large ensemble CRCM5-LE to examine two such compound event types in southern Norway: (1) Heavy rainfall on saturated soil during the summer months (June, July, August, September; SES) and (2) Concurrent heavy rainfall and snowmelt (rain-on-snow; ROS). We compare present-day conditions (1980–2009) with future conditions under a high-emission scenario (2070–2099) and investigate the impact of climate change on the frequency and spatial distribution of SES and ROS events. We find that the probability of occurrence of SES events during the summer increases by 38% until 2070–2099 over the whole study area. The areas with the highest occurrence probability extend from the west coast into the interior. In contrast, the frequency of ROS is projected to decrease by 48% on average, largely driven by decreases in snowfall. Moreover, the spatial pattern of ROS are projected to change, with the most frequently affected areas shifting from the west coast towards the inner country. Our study highlights the benefits of single model large ensemble simulations for the analysis of compound events.

Copyright of Terra Latinoamericana is the property of Sociedad Mexicana de la Ciencia del Suelo A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rift Valley fever (RVF), a zoonotic vectorborne viral disease, causes loss of life among humans and livestock and an adverse effect on the economy of affected countries. Vaccination is the most effective way to protect livestock; however, during protracted interepidemic periods, farmers discontinue vaccination, which leads to loss of herd immunity and heavy losses of livestock when subsequent outbreaks occur. Retrospective analysis of the 2008–2011 RVF epidemics in South Africa revealed a pattern of continuous and widespread seasonal rainfall causing substantial soil saturation followed by explicit rainfall events that flooded dambos (seasonally flooded depressions), triggering outbreaks of disease. Incorporation of rainfall and soil saturation data into a prediction model for major outbreaks of RVF resulted in the correctly identified risk in nearly 90% of instances at least 1 month before outbreaks occurred; all indications are that irrigation is of major importance in the remaining 10% of outbreaks.

• Combined information from geophysics and soil cores delineated soil stratigraphic heterogeneity. • Time-lapse electrical resistivity monitoring revealed preferential infiltration paths. • Hydrological states derived from resistivity monitoring improved a surface–subsurface flow model. • The hydrogeophysical framework captured subsurface flow in response to flooding. This study presents a framework to quantify changes in soil saturation in response to flooding caused by extreme hydrologic perturbation on coastal ecosystems at the interfaces and transition between terrestrial and aquatic systems. Subsurface heterogeneity limits the use of in situ measurements to quantify subsurface flow during flooding due to the spatial discontinuity in the measured data. While geophysical methods, including time-lapse electrical resistivity imaging (ERI), are increasingly used to monitor soil hydrological processes, their abilities to parameterize flow models have been underutilized. This study combines background ERI, ground penetrating radar (GPR), time-lapse ERI, soil characterization, and a numerical flow model developed using an Advanced Terrestrial Simulator (ATS) code to quantify the infiltration pathway and describe the hydrological dynamics during a simulated flooding experiment. We assessed the use of two conceptual models developed using [1] ERI and GPR data that described the stratigraphic distribution, and time-lapse ERI that mapped permeability contrast, and [2] information from a national soil database for capturing changes in saturation. Combining the ERI and GPR results with soil core data revealed the stratigraphic heterogeneity at the site with a silty clay layer from 1 to 2 m between an overlying loamy topsoil and an underlying saturated silty sand. This silty clay layer could restrict deep infiltration. The time-lapse ERI showed up to a 35% decrease in resistivity, which correlated with soil moisture data (R2 value > 0.53) and revealed preferential infiltration zones used to inform the flow model. Numerical simulation results from both the geophysics- and soil database-informed models quantified changes in soil saturation with calculated soil moistures that agreed with field data. The geophysics-informed model captured more of the system's variability, reflective of shallow subsurface heterogeneities. The framework presented will serve as a precursor for a robust ecohydrological model that can describe the impacts of extreme events induced by climate change on coastal ecosystems. [ABSTRACT FROM AUTHOR]

The seismic response of ocean structures would be overestimated if the ground motions recorded at land stations are used without corrections. Considering the effect of soft soil layer and soil saturation with site transfer function, a new method was presented for studied the effect of seawater layer on vertical in-plane motions base on a simple model of Crouse and Quilter. The simulate theory of spatially varying ground motions was proposed to consider the influence of seawater layer and soil saturation of seafloor soil layer. Compared with different site conditions, four unique locate sites with the same spatial distance were chose, and two cases of with seawater and without seawater were studied. The comparison results show that the seafloor vertical in-plane motions are noticeable attenuation under seawater layer. The saturation soft soil layer has more influence on seafloor vertical in-plane motions than seawater. Due to considering the complex submarine topography, the synthesized seafloor ground motions can be applied on numerical simulation in most seafloor seismic hazard analyses. [ABSTRACT FROM AUTHOR]

Thermal conductivity is a key soil property widely used for agricultural production, land surface processing research, and geothermal resource development, among others. Although the rapid and accurate determination of soil thermal conductivity (λ) has been a hot topic in recent years, there is still no unified model for the different soil types of soil. Furthermore, the lack of data on thermal conductivity and soil properties leads to errors in parametric models of thermal conductivity. In order to overcome the data shortage, a comprehensive λ dataset of 2972 items was established and 10 influential parameters on thermal conductivity were identified in this study. Based on this, an empirical comparison was made between four classical parametric models and nine machine-learning models with and without an intelligent optimization algorithm was carried out. Of all the methods, the ensemble machine-learning methods perform better in λ simulations. The XGBoost model has better simulation accuracy and generalization capability. Soil moisture properties are the key parameters in performing λ simulations, while the soil texture-related properties such as bulk density and solid thermal conductivity, along with the sand content, also play an important role. The results of this study can provide basic thermal conductivity data and a parameterization scheme for referencing in land surface processing research. • A dataset of 2972 thermal conductivity entries for 270 soils was established and 10 influential factors were identified. • The XGBoost method is optimal for thermal conductivity simulations. • Soil moisture characteristics water saturation level and content are key input parameters when using machine learning for soil thermal conductivity simulations. [ABSTRACT FROM AUTHOR]

Valley bottomland provides diverse agricultural and ecosystem benefits. Due to concentrated flow paths, they are more vulnerable to gully erosion than hillslope areas. The objective of this review was to show what caused valley bottoms gullies and to present deficiencies in existing rehabilitation measures. From the literature review, we found the following general trends: watershed characteristics determine location of valley bottom gullies; an increase in water transported from the watershed initiates the formation of gullies; the rate of change of the valley bottom gullies, once initiated, depends on the amount of rainfall and the soil and bedrock properties. Especially in humid climates, the presence of subsurface flow greatly enhances bank slippage and advancement of gully heads. Valley bottom gully reclamation measures are generally effective in arid and semi-arid areas with the limited subsurface flow and deep groundwater tables, whereas, for (sub) humid regions, similar remedial actions are not successful as they do not account for the effects of subsurface flows. To ensure effective implementation of rehabilitation measures, especially for humid regions, an integrated landscape approach that accounts for the combined subsurface and surface drainage is needed.

A mesocosm study was conducted to assess the impact of water saturation episodes and of the input of bioavailable organic matter on the biogeochemical cycles of C and N, and on the behavior of metal(loid)s in a soil highly contaminated by the destruction of arsenical shells. An instrumented mesocosm was filled with contaminated soil taken from the “Place-à-Gaz” site. Four cycles of dry and wet periods of about one month were simulated for 276 days. After two dry/wet cycles, organic litter sampled on the site was added above the topsoil. The nitrogen cycle was the most impacted by the wet/dry cycles, as evidenced by a denitrification microbial process in the saturated level. The concentrations of the two most mobile pollutants, Zn and As, in the soil water and in the mesocosm leachate were, respectively, in the 0.3–1.6 mM and 20–110 μM ranges. After 8 months of experiment, about 83 g·m − 3 of Zn and 3.5 g·m − 3 of As were leached from the soil. These important quantities represent < 1% of the solid stock of this contaminant. Dry/wet cycles had no major effect on Zn mobility. However, soil saturation induced the immobilization of As by trapping As V but enhanced As III mobility. These phenomena were amplified by the presence of bioavailable organic matter. The study showed that the natural deposition of forest organic litter allowed a part of the soil's biological function to be restored but did not immobilize all the Zn and As, and even contributed to transport of As III to the surrounding environment. The main hazard of this type of site, contaminated by organo-arsenic chemical weapons, is the constitution of a stock of As that may leach into the surrounding environment for several hundred years. [ABSTRACT FROM AUTHOR]

Rift Valley fever (RVF), a zoonotic vectorborne viral disease, causes loss of life among humans and livestock and an adverse effect on the economy of affected countries. Vaccination is the most effective way to protect livestock; however, during protracted interepidemic periods, farmers discontinue vaccination, which leads to loss of herd immunity and heavy losses of livestock when subsequent outbreaks occur. Retrospective analysis of the 2008-2011 RVF epidemics in South Africa revealed a pattern of continuous and widespread seasonal rainfall causing substantial soil saturation followed by explicit rainfall events that flooded dambos (seasonally flooded depressions), triggering outbreaks of disease. Incorporation of rainfall and soil saturation data into a prediction model for major outbreaks of RVF resulted in the correctly identified risk in nearly 90% of instances at least 1 month before outbreaks occurred; all indications are that irrigation is of major importance in the remaining 10% of outbreaks. [ABSTRACT FROM AUTHOR]

Summary Surface runoff is one of the hydrological processes involved in floods, pollution transfer, soil erosion and mudslide. Many models allow the simulation and the mapping of surface runoff and erosion hazards. Field observations of this hydrological process are not common although they are crucial to evaluate surface runoff models and to investigate or assess different kinds of hazards linked to this process. In this study, a simple field monitoring network is implemented to assess the relevance of a surface runoff susceptibility mapping method. The network is based on spatially distributed observations (nine different locations in the catchment) of soil water content and rainfall events. These data are analyzed to determine if surface runoff occurs. Two surface runoff mechanisms are considered: surface runoff by saturation of the soil surface horizon and surface runoff by infiltration excess (also called hortonian runoff). The monitoring strategy includes continuous records of soil surface water content and rainfall with a 5 min time step. Soil infiltration capacity time series are calculated using field soil water content and in situ measurements of soil hydraulic conductivity. Comparison of soil infiltration capacity and rainfall intensity time series allows detecting the occurrence of surface runoff by infiltration-excess. Comparison of surface soil water content with saturated water content values allows detecting the occurrence of surface runoff by saturation of the soil surface horizon. Automatic records were complemented with direct field observations of surface runoff in the experimental catchment after each significant rainfall event. The presented observation method allows the identification of fast and short-lived surface runoff processes at a small spatial and temporal resolution in natural conditions. The results also highlight the relationship between surface runoff and factors usually integrated in surface runoff mapping such as topography, rainfall parameters, soil or land cover. This study opens interesting prospects for the use of spatially distributed measurement for surface runoff detection, spatially distributed hydrological models implementation and validation at a reasonable cost. [ABSTRACT FROM AUTHOR]

The combination of runoff-generating areas (saturated soils) and overland flow concentration in features such as drainage ditches makes sloping farmland vulnerable to soil erosion. The establishment of drainage ditches aims at draining the excess of water from the farmland, particularly in areas where soils are saturated in the rainy season. The hydrogeomorphic impacts on the farmland itself and on downstream areas need however also to be studied. Off site, downstream problems comprise higher peak discharges, leading to gully initiation, an increase in sediment load, and flooding problems. On-site problems such as the development of the drainage ditches into (ephemeral) gullies are less documented, although they may be important, as illustrated in the Lake Tana Basin (Ethiopia). The similarities and interactions between ephemeral gully channels and drainage ditches have to be considered to better understand all effects of drainage. Drainage ditches are a potential source of conflict between farmers with different interests and power, as well as between upstream and downstream users. A case study on drainage ditches on sloping farmlands in the Lake Tana Basin showed that nine out of ten catchments had drainage densities by ditches ranging from 53 to 510 m ha−1. Drainage ditches were constructed with an average top width of 27 (±9) cm. A significant correlation was found between stone bund density (physical conservation structures) and ditch drainage density ( R = −0·72), in line with the Ethiopian government's ban on drainage ditches in farmlands where stone bunds have been constructed. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]