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https://www.readbyqxmd.com/read/28647245/transport-and-humification-of-dissolved-organic-matter-within-a-semi-arid-floodplain
#1
Wenming Dong, Jiamin Wan, Tetsu K Tokunaga, Benjamin Gilbert, Kenneth H Williams
In order to understand the transport and humification processes of dissolved organic matter (DOM) within sediments of a semi-arid floodplain at Rifle, Colorado, fluorescence excitation-emission matrix (EEM) spectroscopy, humification index (HIX) and specific UV absorbance (SUVA) at 254nm were applied for characterizing depth and seasonal variations of DOM composition. Results revealed that late spring snowmelt leached relatively fresh DOM from plant residue and soil organic matter down into the deeper vadose zone (VZ)...
July 2017: Journal of Environmental Sciences (China)
https://www.readbyqxmd.com/read/28592834/impact-of-naturally-leaking-carbon-dioxide-on-soil-properties-and-ecosystems-in-the-qinghai-tibet-plateau
#2
Xiaohong Zhao, Hongzhang Deng, Wenke Wang, Feng Han, Chunrong Li, Hui Zhang, Zhenxue Dai
One of the major concerns for CO2 capture and storage (CCS) is the potential risk of CO2 leakage from storage reservoirs on the shallow soil property and vegetation. This study utilizes a naturally occurring CO2 leaking site in the Qinghai-Tibet Plateau to analog a "leaking CCS site". Our observations from this site indicates that long-term CO2 invasion in the vadose zone results in variations of soil properties, such as pH fluctuation, slight drop of total organic carbon, reduction of nitrogen and phosphorus, and concentration changes of soluble ions...
June 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28551209/electromagnetic-induction-of-foam-based-nanoscale-zerovalent-iron-nzvi-particles-to-thermally-enhance-non-aqueous-phase-liquid-napl-volatilization-in-unsaturated-porous-media-proof-of-concept
#3
Supawan Srirattana, Kitsanateen Piaowan, Gregory V Lowry, Tanapon Phenrat
Nanoscale zerovalent iron (NZVI) is a promising remediation agent for volatile organic compound (VOC) contamination in saturated sub-surfaces, but is rarely applied to the vadose zone as there are not enough water molecules in the unsaturated zone to participate in reductive dechlorination. In this study, we evaluated the possibility of using foam as a carrying vehicle to emplace NZVI in unsaturated porous media followed by the application of low frequency-electromagnetic field (LF-EMF) to enhance VOC volatilization in laboratory batch reactors...
May 20, 2017: Chemosphere
https://www.readbyqxmd.com/read/28506599/application-of-vadose-zone-monitoring-system-for-real-time-characterization-of-leachate-percolation-in-and-under-a-municipal-landfill
#4
Imri Aharoni, Hagar Siebner, Ofer Dahan
Leachates from solid-waste landfills are considered a severe threat to groundwater quality. The fate of pollutants in the waste and underlying unsaturated zone is crucial for evaluating environmental risks and selecting a restoration strategy. In this study, a vadose-zone monitoring system (VMS) installed in a municipal landfill was used, for the first time, to continuously track leachates percolation dynamics and assess their chemical transformation across the entire thickness of the waste body (15m) and underlying unsaturated zone (16m) to the water table...
May 12, 2017: Waste Management
https://www.readbyqxmd.com/read/28473724/vegetation-controls-on-the-spatio-temporal-heterogeneity-of-deep-moisture-in-the-unsaturated-zone-a-hydrogeophysical-evaluation
#5
Bharat S Acharya, Todd Halihan, Chris B Zou, Rodney E Will
Information on the spatio-temporal variability of soil moisture in the vadose zone is important to assess groundwater recharge and solute transport in unconsolidated substrate as influenced by biological processes. Time-lapse electrical resistivity imaging (ERI) was used to monitor soil moisture dynamics to a depth of 9 m in a grassland, a grassland encroached by a juniper species (eastern redcedar, Juniperus virginiana), a juniper woodland and an oak forest in the south-central Great Plains, Oklahoma, USA...
May 4, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28387232/identification-of-dominating-factors-affecting-vadose-zone-vulnerability-by-a-simulation-method
#6
Juan Li, Beidou Xi, Wutian Cai, Yang Yang, Yongfeng Jia, Xiang Li, Yonggao Lv, Ningqing Lv, Huan Huan, Jinjin Yang
The characteristics of vadose zone vulnerability dominating factors (VDFs) are closely related to the migration and transformation mechanisms of contaminants in the vadose zone, which directly affect the state of the contaminants percolating to the groundwater. This study analyzes the hydrogeological profile of the pore water regions in the vadose zone, and conceptualizes the vadose zone as single lithologic, double lithologic, or multi lithologic. To accurately determine how the location of the pollution source influences the groundwater, we classify the permeabilities (thicknesses) of different media into clay-layer and non-clay-layer permeabilities (thicknesses), and introduce the maximum pollution thickness...
April 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28380569/vadose-zone-transport-of-natural-and-synthetic-estrogen-hormones-at-penn-state-s-living-filter-wastewater-irrigation-site
#7
Emily E Woodward, Danielle M Andrews, Clinton F Williams, John E Watson
No abstract text is available yet for this article.
March 2017: Journal of Environmental Quality
https://www.readbyqxmd.com/read/28314234/investigating-natural-attenuation-of-pharmaceuticals-through-unsaturated-column-tests
#8
Virtudes Martínez-Hernández, Raffaella Meffe, Claus Kohfahl, Irene de Bustamante
The growing consumption of pharmaceuticals together with their incomplete removal in wastewater treatment plants (WWTPs) implies the occurrence of these compounds in natural water resources. To investigate the natural attenuation of selected pharmaceuticals (caffeine, acetaminophen, sulfamethoxazole, naproxen and carbamazepine) during vadose zone infiltration, unsaturated column (L 26.67 cm, Ø 7.62 cm) experiments, filled with a sandy-loamy soil, were performed using two input concentrations (100 and 1000 μg L(-1))...
June 2017: Chemosphere
https://www.readbyqxmd.com/read/28249206/soil-radon-survey-to-assess-napl-contamination-from-an-ancient-spill-do-kerosene-vapors-affect-radon-partition
#9
Gabriele De Simone, Carlo Lucchetti, Francesca Pompilj, Gianfranco Galli, Paola Tuccimei, Pierpaolo Curatolo, Riccardo Giorgi
A soil radon-deficit survey was carried out in a site polluted with kerosene (Rome, Italy) in winter 2016 to assess the contamination due to the NAPL residual component in the vadose zone and to investigate the role of the vapor plume. Radon is indeed more soluble in the residual NAPL than in air or water, but laboratory experiments demonstrated that it is also preferentially partitioned in the NAPL vapors that transport it and may influence soil radon distribution patterns. Specific experimental configurations were designed and applied to a 31-station grid to test this hypothesis; two RAD7 radon monitors were placed in-series and connected to the top of a hollow probe driven up to 80-cm depth; the first instrument was directly attached to the probe and received humid soil gas, which was counted and then conveyed to the second monitor through a desiccant (drierite) cylinder capturing moisture and eventually the NAPL volatile component plus the radon dissolved in vapors...
May 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/28218533/water-table-dynamics-and-biogeochemical-cycling-in-a-shallow-variably-saturated-floodplain
#10
Steven B Yabusaki, Michael J Wilkins, Yilin Fang, Kenneth H Williams, Bhavna Arora, John Bargar, Harry R Beller, Nicholas J Bouskill, Eoin L Brodie, John N Christensen, Mark E Conrad, Robert E Danczak, Eric King, Mohamad R Soltanian, Nicolas F Spycher, Carl I Steefel, Tetsu K Tokunaga, Roelof 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...
March 21, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28071702/nitrogen-loss-by-anaerobic-ammonium-oxidation-in-unconfined-aquifer-soils
#11
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
#12
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...
May 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28007440/effects-of-ammonium-on-uranium-partitioning-and-kaolinite-mineral-dissolution
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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))...
October 2016: Journal of Contaminant Hydrology
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