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vadose zone

Michael Mader, André M Roberts, David Porst, Christian Schmidt, Nico Trauth, Robert van Geldern, Johannes A C Barth
Besides gas-water-exchange in surface waters, respiratory consumption of dissolved oxygen (DO) in adjacent riparian groundwater may trigger the addition of so far hardly explored sources from the unsaturated zone. These processes also systematically influence stable isotope ratios of DO and were investigated together with Cl- as a conservative tracer for water mixing in a near-river riparian groundwater system. The study focused on a losing stream section of the Selke River at the foot of the Harz Mountains (Germany)...
April 5, 2018: Science of the Total Environment
Simin Akbariyeh, Shannon Bartelt-Hunt, Daniel Snow, Xu Li, Zhenghong Tang, Yusong Li
Contamination of groundwater from nitrogen fertilizers in agricultural lands is an important environmental and water quality management issue. It is well recognized that in agriculturally intensive areas, fertilizers and pesticides may leach through the vadose zone and eventually reach groundwater. While numerical models are commonly used to simulate fate and transport of agricultural contaminants, few models have considered a controlled field work to investigate the influence of soil heterogeneity and groundwater flow on nitrate-N distribution in both root zone and deep vadose zone...
February 27, 2018: Journal of Contaminant Hydrology
Behzad Nasri, Olivier Fouché
Depending on the actual number of soil-based on-site wastewater treatment system (OWTS) in an area, on-site sanitation may be a significant source of pollutants and a threat to groundwater. Even in the case of a system functioning correctly, here, a sand filter substituted for the in-situ soil, as the treated effluent may reach to the water table, it is necessary evaluating in situ how much the sand and underneath soil respectively contribute to pollutant removal. On the plot of a household in a small rural community, the functioning of a real scale OWTS was monitored for 1...
February 24, 2018: Environmental Science and Pollution Research International
Xiaoming Song, Yujuan Wen, Yuanyuan Wang, Muhammad Adeel, Yuesuo Yang
The emerging endocrine disrupting chemicals posed high risk and much uncertainty to eco-environment and human health. An analytical method, developed for the simultaneous determination of five steroid estrogens in groundwater and soil based upon solid phase extraction and gas chromatography-mass spectrometry, was applied to investigate the distribution of estrone and 17β-estradiol around Shenyang City with particular focus on penetrating from surface to groundwater in this study. Mean concentrations of the estrone and 17β-estradiol were 55...
January 19, 2018: Chemosphere
Julien Maire, Emmanuelle Brunol, Nicolas Fatin-Rouge
Surfactant foam has been proposed as an effective treatment fluid for in situ environmental remediation of soils. In the vadose zone, it could improve treatment homogeneity, but its use remains challenging. To better understand and predict foam formation and propagation in vadose zone, we studied them in 24 soils with wide range of properties (including permeability: 2 10-12 to 3.3 10-9 m2). Foam rheology showed to be complex and mostly influenced by soil permeability and grading. Below 2 10-11 m2, foam propagation velocity was not influenced by permeability...
January 29, 2018: Chemosphere
Kathryn M Peruski, Melody Maloubier, Daniel I Kaplan, Philip M Almond, Brian A Powell
Due to its radiotoxicity, long half-life, and potentially high environmental mobility, neptunium transport is of paramount importance for risk assessment and safety. Environmental transport of neptunium through field lysimeters at the Savannah River Site was observed from both oxidized (Np(V)) and reduced (Np(IV)) source materials. While transport from oxidized neptunium sources was expected, the unexpected transport from reduced neptunium sources spurred further investigation into transport mechanisms. Partial oxidation of the reduced neptunium source resulted in significant release and transport into the mobile aqueous phase, though a reduced colloidal neptunium species appears to have also been present, enhancing neptunium mobility over shorter distances...
February 20, 2018: Environmental Science & Technology
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 13, 2017: Environmental Science. Processes & Impacts
Jordan L Wilson, V A Samaranayake, Matthew A Limmer, John G Schumacher, Joel G 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...
December 19, 2017: Environmental Science & Technology
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...
February 2018: Environmental Science and Pollution Research International
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
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...
January 1, 2018: Water Research
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- , Ca2+ , Mg2+ , Al3+ , Pb2+ , Cd2+ and Zn2+ , 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...
February 2018: Chemosphere
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
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
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
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
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
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
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...
November 2017: Environmental Science and Pollution Research International
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
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