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https://www.readbyqxmd.com/read/29035418/multi-criteria-evaluation-of-hydro-geological-and-anthropogenic-parameters-for-the-groundwater-vulnerability-assessment
#1
Prashant Kumar, Praveen K Thakur, Baban Ks Bansod, Sanjit K Debnath
Groundwater contamination assessment is a challenging task due to inherent complex dynamisms associated with the groundwater. DRASTIC is a very widely used rapid regional tool for the assessment of vulnerability of groundwater to contamination. DRASTIC has many lacunas in the form of subjectivities associated with weights and ratings of its hydro-geological parameters, and, therefore, the accuracy of the DRASTIC-based vulnerability map is questioned. The present study demonstrates the optimisation of the DRASTIC parameters along with a scientific consideration to the anthropogenic factors causing groundwater contamination...
October 16, 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/29024883/emerging-organic-pollutants-in-the-vadose-zone-of-a-soil-aquifer-treatment-system-pore-water-extraction-using-positive-displacement
#2
Alexander Sopilniak, Roy Elkayam, Anna Voloshenko Rossin, Ovadia Lev
Trace organic compounds in effluents, water streams and aquifers are amply reported. However, the mobile pool of Emerging Organic Contaminants (EOCs) in the deep parts of the vadose zone is hard to estimate, due to difficulties in extraction of sufficient quantity of pore water. Here, we present a new methodology for depth profiling of EOCs in pore water by Positive Displacement Extraction (PDE): Pore water extraction from unsaturated soil samples is carried out by withdrawal of soil cores by direct-push drilling and infiltrating the core by organics free water...
October 3, 2017: Chemosphere
https://www.readbyqxmd.com/read/29022193/development-of-a-modular-vapor-intrusion-model-with-variably-saturated-and-non-isothermal-vadose-zone
#3
Dawit N Bekele, Ravi Naidu, Sreenivasulu Chadalavada
Human health risk assessment at hydrocarbon-contaminated sites requires a critical evaluation of the exposure pathways of volatile organic compounds including assessments of vapor exposure in indoor air. Although there are a number of vapor intrusion models (VIM) currently available, they rarely reproduce actual properties of soils in the vadose zone. At best, users of such models assume averaged parameters for the vadose zone based on information generated elsewhere. The objective of this study was to develop a one-dimensional steady-state VIM, indoorCARE™ model, that considers vertical spatial variations of the degree of saturation (or effective air-filled porosity) and temperature of the vadose zone...
October 12, 2017: Environmental Geochemistry and Health
https://www.readbyqxmd.com/read/28936578/nitrates-and-phosphates-in-cave-waters-of-krak%C3%A3-w-cz%C3%A4-stochowa-upland-southern-poland
#4
Jacek Różkowski, Kazimierz Różkowski, Oimahmad Rahmonov, Hanna Rubin
The paper presents the varied presence of nitrates and phosphates in water from caves located in Częstochowa and Kraków, in urban, strongly anthropogenic conditions, representing the vadose zone of the fissure-karstic-porous massif of Upper Jurassic limestones. Hydrochemical research was carried out by the authors in the Cave on the Stone in Częstochowa in 2012-2015, in caves of the Zakrzówek horst from 1996 to 2002, and in the Dragon's Cave by the research team of J. Motyka in 1995-1998. A number of NO3 and PO4 measurements were performed in waters sampled at these research sites: 20 measurements each of NO3 and PO4 at the Cave on the Stone, 228 of NO3 and 422 of PO4 at Zakrzówek, and 19 each of NO3 and PO4 at the Dragon's Cave...
September 22, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28915454/assessing-the-potential-contributions-of-additional-retention-processes-to-pfas-retardation-in-the-subsurface
#5
Mark L Brusseau
A comprehensive understanding of the transport and fate of per- and poly-fluoroalkyl substances (PFAS) in the subsurface is critical for accurate risk assessments and design of effective remedial actions. A multi-process retention model is proposed to account for potential additional sources of retardation for PFAS transport in source zones. These include partitioning to the soil atmosphere, adsorption at air-water interfaces, partitioning to trapped organic liquids (NAPL), and adsorption at NAPL-water interfaces...
September 12, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28865808/monitoring-the-evolution-and-migration-of-a-methane-gas-plume-in-an-unconfined-sandy-aquifer-using-time-lapse-gpr-and-ert
#6
Colby M Steelman, Dylan R Klazinga, Aaron G Cahill, Anthony L Endres, Beth L Parker
Fugitive methane (CH4) leakage associated with conventional and unconventional petroleum development (e.g., shale gas) may pose significant risks to shallow groundwater. While the potential threat of stray (CH4) gas in aquifers has been acknowledged, few studies have examined the nature of its migration and fate in a shallow groundwater flow system. This study examines the geophysical responses observed from surface during a 72day field-scale simulated CH4 leak in an unconfined sandy aquifer at Canadian Forces Base Borden, Canada, to better understand the transient behaviour of fugitive CH4 gas in the subsurface...
August 30, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/28862461/effects-of-an-extreme-flood-on-trace-elements-in-river-water-from-urban-stream-to-major-river-basin
#7
Larry B Barber, Suzanne S Paschke, William A Battaglin, Chris Douville, Kevin C Fitzgerald, Steffanie H Keefe, David A Roth, Alan M Vajda
Major floods adversely affect water quality through surface runoff, groundwater discharge, and damage to municipal water infrastructure. Despite their importance, it can be difficult to assess the effects of floods on streamwater chemistry because of challenges collecting samples and the absence of baseline data. This study documents water quality during the September 2013 extreme flood in the South Platte River, Colorado, USA. Weekly time-series water samples were collected from 3 urban source waters (municipal tap water, streamwater, and wastewater treatment facility effluent) under normal-flow and flood conditions...
September 1, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28830695/unintentional-contaminant-transfer-from-groundwater-to-the-vadose-zone-during-source-zone-remediation-of-volatile-organic-compounds
#8
Andrea D Chong, K Ulrich Mayer
Historical heavy use of chlorinated solvents in conjunction with improper disposal practices and accidental releases has resulted in widespread contamination of soils and groundwater in North America and worldwide. As a result, remediation of chlorinated solvents is required at many sites. For source zone treatment, common remediation strategies include in-situ chemical oxidation (ISCO) using potassium or sodium permanganate, and the enhancement of biodegradation by primary substrate addition. It is well known that these remediation methods tend to generate gas (carbon dioxide (CO2) in the case of ISCO using permanganate, CO2 and methane (CH4) in the case of bioremediation)...
September 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/28783798/investigating-the-role-of-soil-texture-in-vapor-intrusion-from-groundwater-sources
#9
Yijun Yao, Yue Wang, Zhong Zhong, Mengling Tang, Eric M Suuberg
Soil texture is believed to play a significant role in the migration of subsurface volatile chemicals into buildings at contaminated sites, an exposure process known as vapor intrusion (VI). In this study, we investigated the role of soil texture in determining the attenuation of contaminant soil gas concentration from groundwater source to receptor building. We performed soil column experiments, numerical simulations, and statistical analysis of the USEPA's VI database. The soil column experiments were conducted with commercial sand and soils with sand and sandy loam textures...
July 2017: Journal of Environmental Quality
https://www.readbyqxmd.com/read/28750329/depth-of-the-vadose-zone-controls-aquifer-biogeochemical-conditions-and-extent-of-anthropogenic-nitrogen-removal
#10
B Szymczycha, K D Kroeger, J Crusius, J F Bratton
We investigated biogeochemical conditions and watershed features controlling the extent of nitrate removal through microbial dinitrogen (N2) production within the surficial glacial aquifer located on the north and south shores of Long Island, NY, USA. The extent of N2 production differs within portions of the aquifer, with greatest N2 production observed at the south shore of Long Island where the vadose zone is thinnest, while limited N2 production occurred under the thick vadose zones on the north shore. In areas with a shallow water table and thin vadose zone, low oxygen concentrations and sufficient DOC concentrations are conducive to N2 production...
June 19, 2017: Water Research
https://www.readbyqxmd.com/read/28724099/use-of-%C3%AE-15-n-and-%C3%AE-18-o-values-for-nitrate-source-identification-under-irrigated-crops-a-cautionary-vadose-zone-tale
#11
Shawn E Loo, M Cathryn Ryan, Bernie J Zebarth, Shawn H Kuchta, Denise Neilsen, Bernhard Mayer
Source nitrogen (N) identification of leachate or groundwater nitrate is complicated by N source mixing and N and oxygen (O) isotope fractionation caused by microbial N transformations. This experiment examined the δN and δO values in leachate collected over 1 yr at 55 cm below raspberry ( L.) plots receiving either synthetic fertilizer (FT) or poultry manure (MT). The large ranges of δN (FT: -2.4 to +8.7‰, MT: +1.6 to +9.6‰) and δO (FT: -9.9 to -0.3‰, MT: -10.9 to +1.7‰) values in leachate collected under crop rows prohibited the reliable identification of the applied N sources on individual sampling dates...
May 2017: Journal of Environmental Quality
https://www.readbyqxmd.com/read/28692884/effects-of-hydrated-lime-on-radionuclides-stabilization-of-hanford-tank-residual-waste
#12
Guohui Wang, Wooyong Um, Kirk J Cantrell, Michelle M V Snyder, Mark E Bowden, Mark B Triplett, Edgar C Buck
Chemical stabilization of tank residual waste is part of a Hanford Site tank closure strategy to reduce overall risk levels to human health and the environment. In this study, a set of column leaching experiments using tank C-104 residual waste were conducted to evaluate the leachability of uranium (U) and technetium (Tc) where grout and hydrated lime were applied as chemical stabilizing agents. The experiments were designed to simulate future scenarios where meteoric water infiltrates through the vadose zones into the interior of the tank filled with layers of grout or hydrated lime, and then contacts the residual waste...
October 2017: Chemosphere
https://www.readbyqxmd.com/read/28647245/transport-and-humification-of-dissolved-organic-matter-within-a-semi-arid-floodplain
#13
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
#14
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
#15
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...
September 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
#16
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
#17
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
#18
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
#19
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
#20
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
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