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vadose zone

Hilary P Emerson, Silvina Di Pietro, Yelena Katsenovich, Jim Szecsody
Temporary base treatment is a potential remediation technique for heavy metals through adsorption, precipitation, and co-precipitation with minerals. Manipulation of pH with ammonia gas injection may be especially useful for vadose zone environments as it does not require addition of liquids that would increase the flux towards groundwater. In this research, we conducted laboratory batch experiments to evaluate the changes in uranium mobility and mineral dissolution with base treatments including sodium hydroxide, ammonium hydroxide, and ammonia gas...
June 13, 2018: Journal of Environmental Management
Lin Ma, Yifei Liu, Jing Zhang, Qing Yang, Guanghe Li, Dayi Zhang
Groundwater pollution by emerging contaminants, such as pharmaceutical and personal care products (PPCPs), has caused increasing concerns around the world. The vadose zone is an active zone where lithosphere, hydrosphere and biosphere interact. It is an important medium for PPCPs removal and entry into groundwater from irrigation using wastewater or polluted surface water. In the present study, the occurrence and distribution of eleven PPCPs in areas with a vadose zone (up to 16 m) was investigated from wastewater irrigated farmland, groundwater irrigated farmland and a seasonal river course in Beijing (China)...
June 1, 2018: Science of the Total Environment
Wenguang Sun, H Magdi Selim
Much uncertainty exists in mechanisms and kinetics controlling the adsorption and desorption of molybdenum (Mo) in the soil environment. To investigate the characteristics of Mo adsorption and desorption and predict Mo behavior in the vadose zone, kinetic batch experiments were performed using three soils: Webster loam, Windsor sand and Mahan sand. Adsorption isotherms for Mo were strongly nonlinear for all three soils. Strong kinetic adsorption of Mo by all soils was also observed, where the rate of retention was rapid initially and was followed by slow retention behavior with time...
May 2018: Journal of Environmental Quality
Jérémy Voisin, Benoit Cournoyer, Antonin Vienney, Florian Mermillod-Blondin
Stormwater infiltration systems (SIS) have been built in urban areas to reduce the environmental impacts of stormwater runoff. Infiltration basins allow the transfer of stormwater runoff to aquifers but their abilities to retain contaminants depend on vadose zone properties. This study assessed the influence of vadose zone thickness (VZT) on the transfer of inorganic nutrients (PO4 3- , NO3 - , NH4 + ), dissolved organic carbon (total -DOC- and biodegradable -BDOC-) and bacteria. A field experiment was conducted on three SIS with a thin vadose zone (<3 m) and three SIS with a thick vadose zone (>10 m)...
May 16, 2018: Science of the Total Environment
Xiaoxu Jia, Yuanjun Zhu, Laiming Huang, Xiaorong Wei, Yunting Fang, Lianhai Wu, Andrew Binley, Mingan Shao
Nitrogen (N) stored in deep profiles is important in assessing regional and/or global N stocks and nitrate leaching risk to groundwater. The Chinese Loess Plateau, which is characterized by significantly thick loess deposits, potentially stores immense stocks of mineral N, posing future threats to groundwater quality. In order to determine the vertical distributions of nitrate and ammonium content in the region, as well as to characterize the potential accumulation of nitrate in the deep loess profile, we study loess samples collected at five sites (Yangling, Changwu, Fuxian, An'sai and Shenmu) through a 50 to 200m loess profile...
August 15, 2018: Science of the Total Environment
John N Christensen, Baptiste Dafflon, Alyssa E Shiel, Tetsu K Tokunaga, Jiamin Wan, Boris Faybishenko, Wenming Dong, Kenneth H Williams, Chad Hobson, Shaun T Brown, Susan S Hubbard
Recharge of alluvial aquifers is a key component in understanding the interaction between floodplain vadose zone biogeochemistry and groundwater quality. The Rifle Site (a former U-mill tailings site) adjacent to the Colorado River is a well-established field laboratory that has been used for over a decade for the study of biogeochemical processes in the vadose zone and aquifer. This site is considered an exemplar of both a riparian floodplain in a semiarid region and a post-remediation U-tailings site. In this paper we present Sr isotopic data for groundwater and vadose zone porewater samples collected in May and July 2013 to build a mixing model for the fractional contribution of vadose zone porewater (i...
May 11, 2018: Science of the Total Environment
Amanda R Lawter, Whitney L Garcia, Ravi K Kukkadapu, Odeta Qafoku, Mark E Bowden, Sarah A Saslow, Nikolla P Qafoku
At the Hanford Site in southeastern Washington, discharge of radionuclide laden liquid wastes resulted in vadose zone contamination, providing a continuous source of these contaminants to groundwater. The presence of multiple contaminants (i.e., 99 Tc and 129 I) increases the complexity of finding viable remediation technologies to sequester contaminants in situ and protect groundwater. Although previous studies have shown the efficiency of zero valent iron (ZVI) and sulfur modified iron (SMI) in reducing mobile Tc(VII) to immobile Tc(IV) and iodate incorporation into calcite, the coupled effects from simultaneously using these remedial technologies have not been previously studied...
April 30, 2018: Science of the Total Environment
Lorenzo De Carlo, Marco Berardi, Michele Vurro, Maria Clementina Caputo
In recent years, geophysics is increasingly used to study the flow and transport processes in the vadose zone. Particularly, when the vadose zone is made up of rocks, it is difficult to install sensors in the subsurface to measure hydrological state variables directly. In these cases, the electrical resistivity tomography (ERT) represents a useful tool to monitor the hydrodynamics of the infiltration and to estimate hydraulic parameters and state variables, such as hydraulic conductivity and water content. We propose an integrated approach aimed at predicting water content dynamics in calcarenite, a sedimentary carbonatic porous rock...
April 25, 2018: Environmental Monitoring and Assessment
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)...
September 1, 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...
April 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...
May 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...
April 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
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