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https://www.readbyqxmd.com/read/29192711/nitrification-in-a-soil-aquifer-treatment-system-comparison-of-potential-nitrification-and-concentration-profiles-in-the-vadose-zone
#1
Alexander Sopilniak, Roy Elkayam, Ovadia Lev
The oxidation of ammonium in the vadose zone of soil aquifer systems is discussed and examined by detailed analysis of the depth profiles of dissolved oxygen, nitrate and ammonium concentrations in the vadose zone of a soil-aquifer treatment (SAT) system of a municipal wastewater treatment system of the Tel Aviv metropolitan area. Nitrification kinetics and ammonium adsorption capacity studies show that neither the nitrification rate nor the ammonium adsorption capacity controls the capacity of the Shafdan SAT system for ammonium removal...
December 1, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29182871/contaminant-gradients-in-trees-directional-tree-coring-reveals-boundaries-of-soil-and-soil-gas-contamination-with-potential-applications-in-vapor-intrusion-assessment
#2
Jordan L Wilson, V A Samaranayake, Matthew Alan Limmer, John G Schumacher, Joel Gerard Burken
Contaminated sites pose ecological and human-health risks through exposure to contaminated soil and groundwater. Whereas we can readily locate, monitor, and track contaminants in groundwater, it is harder to perform these tasks in the vadose zone. In this study, tree-core samples were collected at a Superfund site to determine if the sample-collection location around a particular tree could reveal the subsurface location, or direction, of soil and soil-gas contaminant plumes. Contaminant-centroid vectors were calculated from tree-core data to reveal contaminant distributions in directional tree samples at a higher resolution, and vectors were correlated with soil-gas characterization collected using conventional methods...
November 28, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29177997/study-on-diesel-vertical-migration-characteristics-and-mechanism-in-water-bearing-sand-stratum-using-an-automated-resistivity-monitoring-system
#3
Yuying Pan, Yonggang Jia, Yuhua Wang, Xin Xia, Lei Guo
Oil spills frequently occur on both land and sea. Petroleum in mobile phase will cause serious pollution in the sediment and can form a secondary pollution source. Therefore, it is very important to study the migration of petroleum in sediments ideally in a rapid and simplified approach. The release of diesel was simulated using fine beach sand to construct a model aquifer, and dynamic monitoring was carried out using an automated monitoring system including a resistivity probe originally developed by our research group...
November 24, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29123090/global-patterns-of-nitrate-storage-in-the-vadose-zone
#4
M J Ascott, D C Gooddy, L Wang, M E Stuart, M A Lewis, R S Ward, A M Binley
Global-scale nitrogen budgets developed to quantify anthropogenic impacts on the nitrogen cycle do not explicitly consider nitrate stored in the vadose zone. Here we show that the vadose zone is an important store of nitrate that should be considered in future budgets for effective policymaking. Using estimates of groundwater depth and nitrate leaching for 1900-2000, we quantify the peak global storage of nitrate in the vadose zone as 605-1814 Teragrams (Tg). Estimates of nitrate storage are validated using basin-scale and national-scale estimates and observed groundwater nitrate data...
November 10, 2017: Nature Communications
https://www.readbyqxmd.com/read/29102695/modeling-sewage-leakage-and-transport-in-carbonate-aquifer-using-carbamazepine-as-an-indicator
#5
Noam Zach Dvory, Michael Kuznetsov, Yakov Livshitz, Guy Gasser, Irena Pankratov, Ovadia Lev, Eilon Adar, Alexander Yakirevich
The Western Mountain Aquifer (Yarkon-Taninim) of Israel is one of the country's major water resources and partially flows through a karst system. During late winter 2013, maintenance actions were performed on a central sewage pipe that caused sewage to leak into the creek located in the study area. Carbamazepine (CBZ) was used as an indicator for the presence of sewage in the groundwater. The research goal was to develop a mathematical model for quantifying flow and contaminant transport processes in the karst/fractured-porous unsaturated zone and groundwater system...
October 31, 2017: Water Research
https://www.readbyqxmd.com/read/29100125/ion-leaching-and-soil-solution-acidification-in-a-vadose-zone-under-soil-treated-with-sewage-sludge-for-agriculture
#6
Ricardo Perobelli Borba, Victor Sanches Ribeirinho, Otávio Antonio de Camargo, Cristiano Alberto de Andrade, Carmen Silvia Kira, Aline Reneé Coscione
In this study, we performed monitoring of the soil solution (SS) over 10 years on a loamy/clayey-textured Dark Red Dystroferric Oxisol that received sewage sludge for agricultural purposes. The SS was obtained by lysimeters installed along the walls of a well at 1 m, 2 m, 3 m, 4 m and 5 m in depth. The major ions found in the SS were NO3(-), SO4(2-), Cl(-), Ca(2+), Mg(2+), Al(3+), Pb(2+), Cd(2+) and Zn(2+), and the pH level ranged from 4 to 6.5 along the profile. Throughout the first three years of monitoring, the pH to a 3-m depth became more acidic, and in the last year, this trend reached 5 m...
October 25, 2017: Chemosphere
https://www.readbyqxmd.com/read/29081548/a-two-dimensional-analytical-model-of-vapor-intrusion-involving-vertical-heterogeneity
#7
Yijun Yao, Iason Verginelli, Eric M Suuberg
In this work, we present an analytical chlorinated vapor intrusion (CVI) model that can estimate source-to-indoor air concentration attenuation by simulating two-dimensional (2-D) vapor concentration profile in vertically heterogeneous soils overlying a homogenous vapor source. The analytical solution describing the 2-D soil gas transport was obtained by applying a modified Schwarz-Christoffel mapping method. A partial field validation showed that the developed model provides results (especially in terms of indoor emission rates) in line with the measured data from a case involving a building overlying a layered soil...
May 2017: Water Resources Research
https://www.readbyqxmd.com/read/29054658/influence-of-organic-matter-nutrients-and-cyclodextrin-on-microbial-and-chemical-herbicide-and-degradate-dissipation-in-subsurface-sediment-slurries
#8
Kaisa Kerminen, Romain Le Moël, Vilhelmiina Harju, Merja H Kontro
Pesticides leaching from soil to surface and groundwater are a global threat for drinking water safety, as no cleaning methods occur for groundwater environment. We examined whether peat, compost-peat-sand (CPS) mixture, NH4NO3, NH4NO3 with sodium citrate (Na-citrate), and the surfactant methyl-β-cyclodextrin additions enhance atrazine, simazine, hexazinone, dichlobenil, and the degradate 2,6-dichlorobenzamide (BAM) dissipations in sediment slurries under aerobic and anaerobic conditions, with sterilized controls...
October 17, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/29054639/mobility-of-rare-earth-elements-yttrium-and-scandium-from-a-phosphogypsum-stack-environmental-and-economic-implications
#9
Carlos Ruiz Cánovas, Francisco Macías, Rafael Pérez López, José Miguel Nieto
This paper investigates the mobility and fluxes of REE, Y and Sc under weathering conditions from an anomalously metal-rich phosphogypsum stack in SW Spain. The interactions of the phosphogypsum stack with rainfall and organic matter-rich solutions, simulating the weathering processes observed due to its location on salt-marshes, were simulated by leaching tests (e.g. EN 12457-2 and TCLP). Despite the high concentration of REE, Y and Sc contained in the phosphogypsum stack, their mobility during the leaching tests was very low; <0...
October 17, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/29035418/multi-criteria-evaluation-of-hydro-geological-and-anthropogenic-parameters-for-the-groundwater-vulnerability-assessment
#10
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
#11
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
#12
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
#13
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
#14
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...
February 1, 2018: 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
#15
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
#16
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
#17
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
#18
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
#19
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...
October 15, 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
#20
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
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