keyword
MENU ▼
Read by QxMD icon Read
search

vadose zone

keyword
https://www.readbyqxmd.com/read/28218533/water-table-dynamics-and-biogeochemical-cycling-in-a-shallow-variably-saturated-floodplain
#1
Steven B Yabusaki, Michael J Wilkins, Yilin Fang, Kenneth H Williams, Bhavna Arora, John R Bargar, Harry R Beller, Nicholas J Bouskill, Eoin L Brodie, John N Christensen, Mark E Conrad, Robert E Danczak, Eric King, Nicolas F Spycher, Carl I Steefel, Tetsu K Tokunaga, Roelof Jan Versteeg, Scott R Waichler, Haruko M Wainwright
Three-dimensional variably saturated flow and multicomponent biogeochemical reactive transport modeling, based on published and newly generated data, is used to better understand the interplay of hydrology, geochemistry, and biology controlling the cycling of carbon, nitrogen, oxygen, iron, sulfur, and uranium in a shallow floodplain. In this system, aerobic respiration generally maintains anoxic groundwater below an oxic vadose zone until seasonal snowmelt-driven water table peaking transports dissolved oxygen (DO) and nitrate from the vadose zone into the alluvial aquifer...
February 20, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28071702/nitrogen-loss-by-anaerobic-ammonium-oxidation-in-unconfined-aquifer-soils
#2
Shanyun Wang, Dirk Radny, Shuangbing Huang, Linjie Zhuang, Siyan Zhao, Michael Berg, Mike S M Jetten, Guibing Zhu
Anaerobic ammonium oxidation (anammox) is recognized as an important process for nitrogen cycling, yet little is known about its role in the subsurface biosphere. In this study, we investigated the presence, abundance, and role of anammox bacteria in upland soil cores from Tianjin, China (20 m depth) and Basel, Switzerland (10 m depth), using isotope-tracing techniques, (q)PCR assays, and 16 S rRNA &hzsB gene clone libraries, along with nutrient profiles of soil core samples. Anammox in the phreatic (water-saturated) zone contributed to 37...
January 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28058583/assessing-geotechnical-centrifuge-modelling-in-addressing-variably-saturated-flow-in-soil-and-fractured-rock
#3
Brendon R Jones, Luke B Brouwers, Warren D Van Tonder, Matthys A Dippenaar
The vadose zone typically comprises soil underlain by fractured rock. Often, surface water and groundwater parameters are readily available, but variably saturated flow through soil and rock are oversimplified or estimated as input for hydrological models. In this paper, a series of geotechnical centrifuge experiments are conducted to contribute to the knowledge gaps in: (i) variably saturated flow and dispersion in soil and (ii) variably saturated flow in discrete vertical and horizontal fractures. Findings from the research show that the hydraulic gradient, and not the hydraulic conductivity, is scaled for seepage flow in the geotechnical centrifuge...
January 5, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28007440/effects-of-ammonium-on-uranium-partitioning-and-kaolinite-mineral-dissolution
#4
Hilary P Emerson, Silvina Di Pietro, Yelena Katsenovich, Jim Szecsody
Ammonia gas injection is a promising technique for the remediation of uranium within the vadose zone. It can be used to manipulate the pH of a system and cause co-precipitation processes that are expected to remove uranium from the aqueous phase and decrease leaching from the solid phase. The work presented in this paper explores the effects of ammonium and sodium hydroxide on the partitioning of uranium and dissolution of the kaolinite mineral in simplified synthetic groundwaters using equilibrium batch sorption and sequential extraction experiments...
February 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/27986308/corrigendum-to-the-vapor-phase-multi-stage-cmd-test-for-characterizing-contaminant-mass-discharge-associated-with-voc-sources-in-the-vadose-zone-application-to-three-sites-in-different-lifecycle-stages-of-sve-operations-j-contam-hydrol-179-2015-55-64
#5
https://www.readbyqxmd.com/read/27934261/effects-of-flow-regime-on-metal-concentrations-and-the-attainment-of-water-quality-standards-in-a-remediated-stream-reach-butte-montana
#6
Robert L Runkel, Briant A Kimball, David A Nimick, Katherine Walton-Day
Low-flow synoptic sampling campaigns are often used as the primary tool to characterize watersheds affected by mining. Although such campaigns are an invaluable part of site characterization, investigations which focus solely on low-flow conditions may yield misleading results. The objective of this paper is to demonstrate this point and elucidate the mechanisms responsible for the release of metals during rainfall runoff. This objective is addressed using data from diel and synoptic sampling campaigns conducted over a two-day period...
December 6, 2016: Environmental Science & Technology
https://www.readbyqxmd.com/read/27898791/high-removal-of-effluent-borne-nitrogen-with-multiple-external-electron-donors-in-the-engineered-drainfield-of-an-advanced-septic-system
#7
Mriganka De, Gurpal S Toor
Septic systems can be a major source of nitrogen (N) in shallow groundwater. We designed an in situ engineered drainfield with aerobic-anaerobic (sand-woodchips) and anaerobic (elemental sulfur-oyster shell) media to remove N in the vadose zone and reduce N transport to groundwater. Effluent was dispersed on top of the engineered drainfield (3.72 m infiltrative surface) and then infiltrated through the aerobic-anaerobic and anaerobic media before reaching natural soil. Water samples were collected over 64 sampling events (May 2012-December 2013) from three parts of the drainfield: (i) a suction cup lysimeter installed at the sand-woodchips interface, (ii) a pipe after effluent passed through the aerobic-anaerobic media, and (iii) a tank containing anaerobic media...
November 2016: Journal of Environmental Quality
https://www.readbyqxmd.com/read/27836410/using-the-natural-biodegradation-potential-of-shallow-soils-for-in-situ-remediation-of-deep-vadose-zone-and-groundwater
#8
Lior Avishai, Hagar Siebner, Ofer Dahan, Zeev Ronen
In this study, we examined the ability of top soil to degrade perchlorate from infiltrating polluted groundwater under unsaturated conditions. Column experiments designed to simulate typical remediation operation of daily wetting and draining cycles of contaminated water amended with an electron donor. Covering the infiltration area with bentonite ensured anaerobic conditions. The soil remained unsaturated, and redox potential dropped to less than -200mV. Perchlorate was reduced continuously from ∼1150mg/L at the inlet to ∼300mg/L at the outlet in daily cycles...
February 15, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/27773440/a-simple-model-to-predict-chromate-partitioning-in-selected-soils-from-china
#9
Xueyuan Gu, Jinyu Xie, Xiaorong Wang, Les J Evans
Due to its mobility and toxicity, chromate [Cr(VI)] partitioning in soils, especially in the vadose zone, is an important environmental concern. The aim of this study was to develop a mechanism-based multi-surface complexation model using published parameters to predict the soil/water partitioning of Cr(VI) in 12 soils (previously depleted of organic matter) from China. The retention of Cr(VI) in soils was attributed to two reactive oxide surfaces: goethite and hydrous ferric oxide (HFO); however, modeling results showed that the best prediction was obtained with goethite alone, whereas the addition of HFO resulted in an overestimation of adsorption in some soils...
October 17, 2016: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/27665617/risk-based-prioritization-method-for-the-classification-of-groundwater-pollution-from-hazardous-waste-landfills
#10
Yu Yang, Yong-Hai Jiang, Xin-Ying Lian, Bei-Dou Xi, Zhi-Fei Ma, Xiang-Jian Xu, Da An
Hazardous waste landfill sites are a significant source of groundwater pollution. To ensure that these landfills with a significantly high risk of groundwater contamination are properly managed, a risk-based ranking method related to groundwater contamination is needed. In this research, a risk-based prioritization method for the classification of groundwater pollution from hazardous waste landfills was established. The method encompasses five phases, including risk pre-screening, indicator selection, characterization, classification and, lastly, validation...
September 24, 2016: Environmental Management
https://www.readbyqxmd.com/read/27639976/implications-of-the-change-in-confinement-status-of-a-heterogeneous-aquifer-for-scale-dependent-dispersion-and-mass-transfer-processes
#11
D Pedretti, A Molinari, C Fallico, S Guzzi
A series of experimental tracer tests were performed to explore the implications of the change in the pressure status of a heterogeneous bimodal aquifer for scale-dependent dispersion and mass-transfer processes. The sandbox was filled with sands and gravel channels and patches to form an alluvial-like bimodal aquifer. We performed multiple injections of a conservative tracer from 26 different locations of the sandbox and interpreted the resulting depth-integrated breakthrough curves (BTCs) at the central pumping well to obtain a scale-dependent distribution of local and field-integrated apparent longitudinal dispersivity (respectively, αL(loc) and αL(app))...
September 9, 2016: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/27639465/transformation-and-speciation-of-typical-heavy-metals-in-soil-aquifer-treatment-system-during-long-time-recharging-with-secondary-effluent-depth-distribution-and-combination
#12
Liangliang Wei, Kun Wang, Daniel R Noguera, Junqiu Jiang, Ben Oyserman, Ningbo Zhao, Qingliang Zhao, Fuyi Cui
Soil aquifer treatment (SAT) systems rely on extensive physical and biogeochemical processes in the vadose zone and aquifer for water quality improvement. In this study, the distribution, quantitative changes, as well as the speciation characteristics of heavy metals in different depth of soils of a two-year operated lab-scale SAT was explored. A majority of the heavy metals in the recharged secondary effluent were efficiently trapped by the steady-state operated SAT (removal efficiency ranged from 74.7% to 98...
December 2016: Chemosphere
https://www.readbyqxmd.com/read/27581045/transport-of-sulfonamide-antibiotics-in-crop-fields-during-monsoon-season
#13
Jong Yol Park, Marianne Ruidisch, Bernd Huwe
Previous studies have documented the occurrence of veterinary sulfonamide antibiotics in groundwater and rivers located far from pollution sources, although their transport and fate is relatively unknown. In mountainous agricultural fields, the transport behaviour can be influenced by climate, slope and physico-chemical properties of the sulfonamides. The objective of this research is to describe the transport behaviour of three sulfonamide antibiotics (sulfamethoxazole, sulfadimethoxine and sulfamethazine) in sloped agricultural fields located in the Haean catchment, South Korea...
November 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/27575368/temporal-variations-of-water-productivity-in-irrigated-corn-an-analysis-of-factors-influencing-yield-and-water-use-across-central-nebraska
#14
Tony Carr, Haishun Yang, Chittaranjan Ray
Water Productivity (WP) of a crop defines the relationship between the economic or physical yield of the crop and its water use. With this concept it is possible to identify disproportionate water use or water-limited yield gaps and thereby support improvements in agricultural water management. However, too often important qualitative and quantitative environmental factors are not part of a WP analysis and therefore neglect the aspect of maintaining a sustainable agricultural system. In this study, we examine both the physical and economic WP in perspective with temporally changing environmental conditions...
2016: PloS One
https://www.readbyqxmd.com/read/27570196/setback-distances-between-small-biological-wastewater-treatment-systems-and-drinking-water-wells-against-virus-contamination-in-alluvial-aquifers
#15
A P Blaschke, J Derx, M Zessner, R Kirnbauer, G Kavka, H Strelec, A H Farnleitner, L Pang
Contamination of groundwater by pathogenic viruses from small biological wastewater treatment system discharges in remote areas is a major concern. To protect drinking water wells against virus contamination, safe setback distances are required between wastewater disposal fields and water supply wells. In this study, setback distances are calculated for alluvial sand and gravel aquifers for different vadose zone and aquifer thicknesses and horizontal groundwater gradients. This study applies to individual households and small settlements (1-20 persons) in decentralized locations without access to receiving surface waters but with the legal obligation of biological wastewater treatment...
December 15, 2016: Science of the Total Environment
https://www.readbyqxmd.com/read/27548959/-characteristics-and-transport-patterns-of-ammonia-nitrites-nitrates-and-inorganic-nitrogen-flux-at-epikarst-springs-and-a-subterranean-stream-in-nanshan-chongqing
#16
Yuan-zhu Zhang, Qiu-fang He, Yong-jun Jiang, Yong Li
In a karst groundwater system, it develops complex multiple flows because of its special geological structure and unique physical patterns of aquifers. In order to investigate the characteristics and transport patterns of ammonia, nitrite and nitrate in epikarst water and subterranean stream, the water samples were collected monthly in a fast-urbanizing karst region. The results showed distinctive characteristics of three forms of inorganic nitrogen. The concentration of inorganic nitrogen was stable in the epikarst water while it was fluctuant in the subterranean stream...
April 15, 2016: Huan Jing Ke Xue= Huanjing Kexue
https://www.readbyqxmd.com/read/27523982/natural-attenuation-of-nonvolatile-contaminants-in-the-capillary-fringe
#17
Zohre Kurt, E Erin Mack, Jim C Spain
When anoxic polluted groundwater encounters the overlying vadose zone an oxic/anoxic interface is created, often near the capillary fringe. Biodegradation of volatile contaminants in the capillary fringe can prevent vapor migration. In contrast, the biodegradation of nonvolatile contaminants in the vadose zone has received comparatively little attention. Nonvolatile compounds do not cause vapor intrusion, but they still move with the groundwater and are major contaminants. Aniline (AN) and diphenylamine (DPA) are examples of toxic nonvolatile contaminants found often at dye and munitions manufacturing sites...
September 20, 2016: Environmental Science & Technology
https://www.readbyqxmd.com/read/27508082/optimization-of-drastic-method-by-artificial-neural-network-nitrate-vulnerability-index-and-composite-drastic-models-to-assess-groundwater-vulnerability-for-unconfined-aquifer-of-shiraz-plain-iran
#18
Mohammad Ali Baghapour, Amir Fadaei Nobandegani, Nasser Talebbeydokhti, Somayeh Bagherzadeh, Ata Allah Nadiri, Maryam Gharekhani, Nima Chitsazan
BACKGROUND: Extensive human activities and unplanned land uses have put groundwater resources of Shiraz plain at a high risk of nitrate pollution, causing several environmental and human health issues. To address these issues, water resources managers utilize groundwater vulnerability assessment and determination of protection. This study aimed to prepare the vulnerability maps of Shiraz aquifer by using Composite DRASTIC index, Nitrate Vulnerability index, and artificial neural network and also to compare their efficiency...
2016: Journal of Environmental Health Science & Engineering
https://www.readbyqxmd.com/read/27380070/validation-of-sensor-directed-spatial-simulated-annealing-soil-sampling-strategy
#19
Elia Scudiero, Scott M Lesch, Dennis L Corwin
Soil spatial variability has a profound influence on most agronomic and environmental processes at field and landscape scales, including site-specific management, vadose zone hydrology and transport, and soil quality. Mobile sensors are a practical means of mapping spatial variability because their measurements serve as a proxy for many soil properties, provided a sensor-soil calibration is conducted. A viable means of calibrating sensor measurements over soil properties is through linear regression modeling of sensor and target property data...
July 2016: Journal of Environmental Quality
https://www.readbyqxmd.com/read/27228305/geoelectrical-monitoring-of-simulated-subsurface-leakage-to-support-high-hazard-nuclear-decommissioning-at-the-sellafield-site-uk
#20
Oliver Kuras, Paul B Wilkinson, Philip I Meldrum, Lucy S Oxby, Sebastian Uhlemann, Jonathan E Chambers, Andrew Binley, James Graham, Nicholas T Smith, Nick Atherton
A full-scale field experiment applying 4D (3D time-lapse) cross-borehole Electrical Resistivity Tomography (ERT) to the monitoring of simulated subsurface leakage was undertaken at a legacy nuclear waste silo at the Sellafield Site, UK. The experiment constituted the first application of geoelectrical monitoring in support of decommissioning work at a UK nuclear licensed site. Images of resistivity changes occurring since a baseline date prior to the simulated leaks revealed likely preferential pathways of silo liquor simulant flow in the vadose zone and upper groundwater system...
October 1, 2016: Science of the Total Environment
keyword
keyword
61462
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"