A vadose zone Transport Processes Investigation within the glacial till at the Fernald Environmental Management Project.

<p>Environmental tracers, present in the environment and provided by nature, provide integrative information about both water flow and transport. For studying water flow and solute transport, the hydrogen and oxygen isotopes are of special interest, as their ratios provide a tracer signal with every precipitation event and are seasonally distributed. In order to follow the seasonal distribution of stable isotopes in the soil water and use this information for identifying hydrological processes and hydraulic properties, soil was sampled three times in three profiles, two on Kr&#353;ko polje aquifer in SE Slovenia and one on Ljubljansko polje in central Slovenia. Isotope composition of soil water was measured with the water-vapor-equilibration method. Based on the isotope composition of soil water integrative information about water flow and transport processes with time and depth below ground were assessed. Porewater isotopes were in similar range as precipitation for all three profiles. &#160;Variable isotope ratios in the upper 60 cm for the different sampling times indicated dynamic water fluxes in this upper part of the vadose zone. Results also showed more evaporation at one sampling location, Brege. The information from stable isotopes will be of importance for further analyzing the water fluxes in the vadose zone of the study sties.&#160;<br>This research was financed by the ARRS BIAT 20-21-32 and IAEA CRP 1.50.18 Multiple isotope fingerprints to identify sources and transport of agro-contaminants. &#160;</p>

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Vadose Zone, Part I : Characterization and Flow Processes

Applied Stochastic Hydrogeology ◽

10.1093/oso/9780195138047.003.0016 ◽

2003 ◽

Author(s):

Yoram Rubin

Keyword(s):

Porous Media ◽

Water Flow ◽

Governing Equation ◽

Vadose Zone ◽

Stochastic Analysis ◽

Transport Processes ◽

Richards Equation ◽

Saturated Porous Media ◽

Flow And Transport ◽

Flow Processes

Many of the principles guiding stochastic analysis of flow and transport processes in the vadose zone are those which we also employ in the saturated zone, and which we have explored in earlier chapters. However, there are important considerations and simplifications to be made, given the nature of the flow and of the governing equations, which we explore here and in chapter 12. The governing equation for water flow in variably saturated porous media at the smallest scale where Darcy’s law is applicable (i.e., no need for upscaling of parameters) is Richards’ equation (cf. Yeh, 1998)

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Numerical Modeling on Fate and Transport of Pollutants in the Vadose Zone

Environmental Sciences Proceedings ◽

10.3390/environsciproc2020002034 ◽

2020 ◽

Vol 2 (1) ◽

pp. 34 ◽

Cited By ~ 1

Author(s):

Giacomo Viccione ◽

Maria Grazia Stoppiello ◽

Silvia Lauria ◽

Leonardo Cascini

Keyword(s):

Vadose Zone ◽

Contaminated Soils ◽

Fate And Transport ◽

Transport Processes ◽

Saturated Soils ◽

Saturated Porous Media ◽

Campania Region ◽

Partially Saturated ◽

Partially Saturated Soils ◽

Method Approach

Soil contamination is an issue of paramount importance to assess human health (HHRA) as well as ecological (ERA) risk assessment. To analyze risk scenarios related to contaminated soils, the identification of sources, either of primary or secondary type, as well as the assessment of propagation and fate processes is needed. Although many studies refer to the transport of pollutants in fully saturated porous media, little efforts have been made concerning the case of partially saturated soils so far. The matter is of interest as the contamination in the fully saturated region may take place as a result of the percolation in the vadose zone. Governing equations ruling fate and transport processes in partially saturated soils are here solved numerically by means of a finite element method approach. Richards equations are adopted to describe flow dynamics through the hydraulic conductivity coefficient Ks, while contaminant fate is mainly described by the sorption coefficient Kp. As for the boundary conditions, we consider a local and continuous spill of contaminant at the upper ground of variable thickness. Precipitations are given as step functions whose intensity is derived by considering pluviometric data at the station of Gròmola, Campania Region, Italy. Benzene and tetrachloroethylene (PCE) are taken into account. A comparative analysis is carried out for permeability Ks and distribution Kd coefficients in the range [10−6, 10−4] m/s and [10−5, 10−3] m3/kg. Results are then compared and discussed.

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Integrated Systems-Based Approach to Monitoring Environmental Remediation

Volume 2: Facility Decontamination and Decommissioning; Environmental Remediation; Environmental Management/Public Involvement/Crosscutting Issues/Global Partnering ◽

10.1115/icem2013-96010 ◽

2013 ◽

Cited By ~ 1

Author(s):

Michael J. Truex ◽

Amoret L. Bunn ◽

Mart Oostrom ◽

K. C. Carroll ◽

Dawn M. Wellman

Keyword(s):

Surface Water ◽

Vadose Zone ◽

Environmental Remediation ◽

Unsaturated Flow ◽

Transport Processes ◽

Department Of Energy ◽

Integrated Systems ◽

Monitoring Design ◽

Contaminant Flux

The U.S. Department of Energy is responsible for risk reduction and cleanup of its nuclear weapons complex. Remediation strategies for some of the contamination may include techniques that mitigate risk, but leave contaminants in place. Monitoring to verify remedy performance and long-term mitigation of risk is key to implementing these strategies and can be a large portion of the total cost of remedy implementation. Especially in these situations, there is a need for innovative monitoring approaches that move away from the cost- and labor-intensive point-source monitoring. In this paper, alternative approaches for monitoring are presented for vadose zone, groundwater, groundwater/surface water interface, and surface water. To illustrate integrated, systems-based monitoring, this paper focuses on vadose zone contaminant remediation to mitigate impact to groundwater. In this context, vadose zone contamination is a source, or potential source, to groundwater plumes. The monitoring design uses a systems-based approach focused on developing a conceptual site model that highlights key features that control contaminant flux to groundwater. These features are derived considering the unsaturated flow and contaminant transport processes in the vadose zone and the nature of the waste discharge. Diagnostic properties and/or parameters related to both short- and long-term contaminant flux to groundwater can be identified and targeted for monitoring. The resolution of monitoring data needed to correspond to a functionally useful indicator of flux to groundwater can be estimated using quantitative analyses and the associated unsaturated flow properties relevant to the targeted site and vadose zone features. This monitoring design approach follows the process of developing a quantitative conceptual model suitable for supporting projections of future flux to groundwater. Support for such projections is important because it is likely that, in many cases, remediation decisions for the vadose zone will need to be made based all or in part on projected impacts to groundwater, and monitoring will then be applied to verify that remedy goals are being met.

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