790 results
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Journal Article
Methane-Oxidizing Bacteria Communities Shift to Attenuate a Controlled Vadose Zone Methane Release
Methane generated from small-rate releases of ethanol-blended fuels into the vadose zone potentially poses health and safety risks. Ubiquitous methane-oxidizing bacteria (MOB) in soils can convert CH into CO, potentially alleviating these risks. Understanding MOB ecology can help to better predict…
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Journal Article
Review and Evaluation of Root Respiration and of Natural and Agricultural Processes of Soil Aeration
Soil aeration processes and status are reviewed with regard to different soil, climatic, land-use, and crop types and with regard to diffusive and advective flow mechanisms. Factors affecting aeration status and its quantifiers are discussed and active soil aeration (“oxygation”) practices are…
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Journal Article
Soil Hydraulic Modeling Outcomes with Four Parameterization Methods: Comparing Soil Description and Inverse Estimation Approaches
Different methods for parameterizing soil hydraulic models can lead to substantially varied predictions of soil–plant–atmosphere water fluxes. This study investigated, for a heterogeneous stony soil, four methods of soil hydraulic parameterization: (i) use of a pedotransfer function with a…
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Journal Article
Methane Transport during a Controlled Release in the Vadose Zone
Shallow, small-rate releases of ethanol-blended fuels from underground storage tanks (USTs) may be quite common and result in subsurface CH generation. However, vadose zone transport of CH generated from these fuel releases is poorly understood, despite the potential to promote vapor intrusion or…
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Journal Article
Extreme Precipitation Years and Their Occurrence Frequency Regulate Long-Term Groundwater Recharge and Transit Time
Deep drainage, defined as the water flux below the plant root zone, is potential groundwater recharge in arid and semiarid regions but remains poorly understood. This study aims to explore long-term (1901–2015) deep drainage (at the 75-m depth) in a semiarid region with deep unsaturated zone (>90-m…
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Journal Article
A Comparison of Ground-Penetrating Radar Early-Time Signal Approaches for Mapping Changes in Shallow Soil Water Content
Improving irrigation efficiency requires accurate assessment of the soil moisture distribution in time and space, but obtaining accurate observational data is challenging. Early-time signal (ETS) amplitude analysis of ground-penetrating radar (GPR) data may permit such rapid noninvasive…
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Journal Article
Numerical and Experimental Investigations of Cesium and Strontium Sorption and Transport in Agricultural Soils
A process-based knowledge of the sorption mechanisms in soils is a prerequisite for the prediction of radionuclide transport in soils, plant availability, and leaching risk into groundwater. The present study combined batch sorption experiments of Cs and Sr in agricultural soils of differing soil…
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Journal Article
Modeling Solute Mass Exchange between Pore Regions in Slurry-Injected Soil Columns during Intermittent Irrigation
Animal slurry application to agricultural land can be a threat to the quality of groundwater and nearby surface water bodies by percolation of solutes from slurry sources. We hypothesized that local-scale processes, such as mass exchange between preferential flow paths and matrix pore regions, can…
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Journal Article
Updating the Coupling Algorithm between HYDRUS and MODFLOW in the HYDRUS Package for MODFLOW
The HYDRUS-based flow package for MODFLOW (the HPM or the HYDRUS package) is an existing unsaturated zone flow package for MODFLOW. In MODFLOW with the HPM, the groundwater modeling domain is discretized into regular grids that can be combined into multiple zones based on similarities in soil…
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Journal Article
SoilJ: An ImageJ Plugin for the Semiautomatic Processing of Three-Dimensional X-ray Images of Soils
Noninvasive three- and four-dimensional X-ray imaging approaches have proved to be valuable analysis tools for vadose zone research. One of the main bottlenecks for applying X-ray imaging to data sets with a large number of soil samples is the relatively large amount of time and expertise needed to…
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Journal Article
Downscaling of SMAP Soil Moisture Using Land Surface Temperature and Vegetation Data
Remotely sensed soil moisture retrieved by the Soil Moisture Active and Passive (SMAP) sensor is currently provided at a 9-km grid resolution. Although valuable, some applications in weather, agriculture, ecology, and watershed hydrology require soil moisture at a higher spatial resolution. In this…
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Journal Article
Lysimeters in Vadose Zone Research
Lysimeters are methodological experimental tools to study the water and matter fluxes in the vadose zone, as well as the environmental fate of chemicals. Lysimeters are available in various types. The most sophisticated lysimeters are filled monolithically, are equipped with a pressure-controlled…
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Journal Article
HOBE: The Danish Hydrological Observatory
The Danish hydrological observatory was established in 2007 in a catchment in the western part of Denmark representing hydrological conditions in a temperate climate with groundwater-dominated streamflow. In the catchment, an experimental infrastructure has been established where measurements…
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Journal Article
Establishing Vadose Zone Slow-Release Carbon Sources for Enhanced Bioremediation Using Silica Suspension
Delivery of C sources (nutrients) to the vadose zone and establishing a slow-release C source in this unsaturated zone are essential for promoting long-term, enhanced contaminant bioremediation at sites with deep vadose zones, such as the Hanford Site in the southeast of the state of Washington…
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Journal Article
Engineering Rhizosphere Hydraulics: Pathways to Improve Plant Adaptation to Drought
Recent studies have drawn attention to the role of mucilage in shaping rhizosphere hydraulic properties and regulating root water uptake. During drying, mucilage keeps the rhizosphere wet and conductive, but on drying it turns hydrophobic, limiting root water uptake. In this study, we introduce the…
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Journal Article
Imidacloprid Sorption and Transport in Cropland, Grass Buffer, and Riparian Buffer Soils
An understanding of neonicotinoid sorption and transport in soil is critical for determining and mitigating environmental risk associated with the most widely used class of insecticides. The objective of this study was to evaluate mobility and transport of the neonicotinoid imidacloprid (ICD) in…
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Journal Article
Seasonal Effects on Leachate Quality from an Ozark Highlands Managed Grassland Using Automated, Equilibrium-Tension Lysimeters
In regions with concentrated broiler () production, land application is a useful means of managing broiler litter (BL). However, surface and subsurface water quality issues may arise when continued annual BL application to fields occurs for extended periods. The application of manure follows…
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Journal Article
Drivers of Potential Recharge from Irrigated Agroecosystems in the Wisconsin Central Sands
The expansion of irrigated agriculture on landscapes underlain by coarse-grained, glacial aquifers in Wisconsin, Minnesota, and Michigan changes the timing and magnitude of groundwater recharge. Water managers require improved estimates of groundwater recharge to manage pumping impacts on…
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Journal Article
A Direct-Push Freezing Core Barrel for Sampling Unconsolidated Subsurface Sediments and Adjacent Pore Fluids
Contaminants passing through the unsaturated zone can undergo changes in narrow reaction zones upon reaching saturated sediments. Understanding these reactions requires sampling of sediment together with adjacent water and microbes in a manner that preserves in situ redox conditions. Use of a…