Recently there is an increasing interest in the understanding of the Spectral Induced Polarizatio... more Recently there is an increasing interest in the understanding of the Spectral Induced Polarization (SIP) phenomenon in porous media. The complex electrical conductivity of porous geological materials has a frequency dependent behavior than can be associated to three main mechanisms: Maxwell-Wagner (MW) polarization, Membrane polarization, Electrical double layer (EDL) polarization. This paper aims to develop a mechanistic model for induced polarization in frequency domain, that incorporates both grain and membrane polarization and uses a non-linear mixing rule to combine the contribution of water, air and solid grains. The model is tested on two different lab experimental datasets. Different spectra characteristics can be understood and described by distinguished porous media behaviors.
For decades, bad practices in municipal and industrial waste management have had negative environ... more For decades, bad practices in municipal and industrial waste management have had negative environmental impacts, generating high health risks for people and the environment. The use of badly designed, not engineered, and not well-operated landfills has, around the world, produced a large number of potentially contaminated sites, for which there are urgent needs to assess the actual risk and to proceed, in case, with reclamation activities. One of these sites, an abandoned waste disposal site located near a Site of Community Importance on the central-eastern coast of Sardinia (Italy), is the subject of the case history described in this work. As a part of a multi-method geophysical characterisation, a frequency-domain electromagnetic (FDEM) mapping survey was carried out with the specific aim of detecting the presence of buried materials (waste) and of delineating the lateral extent of the landfill by identifying the electrical conductivity anomalies produced, for the most part, by t...
Abstract Noninvasive methods for the characterization of shallow subsurface have been used routin... more Abstract Noninvasive methods for the characterization of shallow subsurface have been used routinely for some 20–30 years. The growth in these methods has been driven by a variety of breakthroughs in the use of electrical, electromagnetic, and seismic methods, to mention only the most common techniques. Increasing field capabilities and computational power have yet to yield all their potential fruits. In this chapter, we introduce readers to the basic concepts of shallow subsurface methods. We guide them through some of the physical details and present a number of application examples all derived from our own experience, concerning both structural characterization and (fluid)-dynamic understanding of the shallow subsurface. Finally, we propose ideas concerning the future development of this wide and exciting discipline.
Environmental Science and Pollution Research, 2021
The remediation of petroleum-contaminated soil and groundwater is a challenging task. The petrole... more The remediation of petroleum-contaminated soil and groundwater is a challenging task. The petroleum hydrocarbons have a long persistence in both the vadose zone and in the aquifer and potentially represent secondary and residual sources of contamination. This is particularly evident in the presence of residual free-phase. Pump-and-treat is the most common hydrocarbon decontamination strategy. Besides, it acts primarily on the water dissolved phase and reduces concentrations of contaminants to an asymptotic trend. This study presents a case of enhanced light non-aqueous phase liquid (LNAPL) remediation monitored using noninvasive techniques. A pilot-scale field experiment was conducted through the injection of reagents into the subsoil to stimulate the desorption and the oxidation of residual hydrocarbons. Geophysical and groundwater monitoring during pilot testing controlled the effectiveness of the intervention, both in terms of product diffusion capacity and in terms of effective ...
Hydrogeological uniqueness and chemical-physical peculiarities guide the contamination dynamics a... more Hydrogeological uniqueness and chemical-physical peculiarities guide the contamination dynamics and decontamination mechanisms in the environmental arena. A single composite geodatabase, which integrates geological/hydrological, geophysical, and chemical data, acts as a “cockpit” in the definition of a conceptual model, design of a remediation strategy, implementation, near-real-time monitoring, and validation/revision of a pilot test, and monitoring full-scale interventions. The selected remediation strategy involves the creation of "reactive" zones capable of reducing the concentration of chlorinated solvents in groundwater through the combined action of adsorption on micrometric activated carbon, which is injected into the aquifer, and degradation of organic contaminants, stimulating the dechlorinating biological activity by the addition of an electron donor. The technology is verified through a pilot test, to evaluate the possibility of scaling up the process. The resu...
Previous studies have demonstrated the potential benefits of the complex conductivity (CC) imagin... more Previous studies have demonstrated the potential benefits of the complex conductivity (CC) imaging over electrical resistivity tomography for an improved delineation of hydrocarbon-impacted sites and accompanying biogeochemical processes. However, time-lapse CC field applications are still rare, in particular for measurements performed near anthropogenic structures such as buried pipes or tanks, which are typically present at contaminated sites. To fill this gap, we have developed CC imaging (CCI) results for monitoring data collected in Trecate (northwest Italy), a site impacted by a crude oil spill. Initial imaging results reveal only a poor correlation with seasonal variations of the groundwater table at the site (approximately 6 m). However, it is not clear to which extend such results are affected by anthropogenic structures present at the site. To address this, we performed a detailed analysis of the misfit between direct and reciprocal time-lapse differences. Based on this an...
Whether or not one can detect relict signatures of the past imprinted in current landscapes is a ... more Whether or not one can detect relict signatures of the past imprinted in current landscapes is a question of the utmost theoretical and practical relevance for meandering tidal channels, owing to their influence on the morphodynamic evolution of tidal landscapes, a critically fragile environment, especially in face of expected climatic changes. Unravelling the sedimentary patterns of ancient channels is an expensive process that usually requires high resolution sediment coring. Here we use a novel inversion process of multi-frequency electromagnetic measurements to reveal the signature and characterize the dynamics of a salt-marsh paleo-meander in the Venice Lagoon. We show that the ancient meander migrated laterally while vertically aggrading, developing a peculiar bar geometry which is less common in analogous fluvial meanders. The observed point-bar dynamics and the associated architectural geometry are consistent with remote sensing and borehole data and contrast with current as...
A problematic aspect characterizing field tracer tests monitored by hydrogeophysical methods, suc... more A problematic aspect characterizing field tracer tests monitored by hydrogeophysical methods, such as Electrical Resisitivity Tomography (ERT), is a correct definition of the initial distribution of the solute in the injection volume. An incomplete or erroneous knowledge of the initial conditions can in fact heavily affect the interpretation of the tests, typically resulting in large errors on the estimation of
In the framework of the Research Strategic Project Geo-Risks "Geological and hydrological pr... more In the framework of the Research Strategic Project Geo-Risks "Geological and hydrological processes: monitoring, modeling and impact in the North-East Italy", a seismic reflection survey and surface waves analysis were performed on the Mt. Toc landslide in the Vajont Valley, Italy. The aim of the geophysical measurements was to obtain a 2D geophysical model of the entire landslide body down to the sliding surface depth and the characterization of rock seismic velocities. Due to the critical environment, another aim of the project was also to explore the feasibility and limitations of these geophysical tools in large landslide studies. The seismic reflection survey was conducted along two lines: L1 and L2, that are 510 and 322 m long respectively, with a - 'Vibroseis' - operating in the vertical mode (P wave) and vertical geophones. L1 was also acquired with - 'Vibroseis' - in horizontal mode (SH) and horizontal geophones. The Frequency Time Analysis of surf...
The Science of the total environment, Jan 15, 2015
Water scarcity is a serious environmental problem in many European regions, and will likely incre... more Water scarcity is a serious environmental problem in many European regions, and will likely increase in the near future as a consequence of increased abstraction and climate change. Water scarcity exacerbates the effects of multiple stressors, and thus results in decreased water quality. It impacts river ecosystems, threatens the services they provide, and it will force managers and policy-makers to change their current practices. The EU-FP7 project GLOBAQUA aims at identifying the prevalence, interaction and linkages between stressors, and to assess their effects on the chemical and ecological status of freshwater ecosystems in order to improve water management practice and policies. GLOBAQUA assembles a multidisciplinary team of 21 European plus 2 non-European scientific institutions, as well as water authorities and river basin managers. The project includes experts in hydrology, chemistry, biology, geomorphology, modelling, socio-economics, governance science, knowledge brokerag...
Recently there is an increasing interest in the understanding of the Spectral Induced Polarizatio... more Recently there is an increasing interest in the understanding of the Spectral Induced Polarization (SIP) phenomenon in porous media. The complex electrical conductivity of porous geological materials has a frequency dependent behavior than can be associated to three main mechanisms: Maxwell-Wagner (MW) polarization, Membrane polarization, Electrical double layer (EDL) polarization. This paper aims to develop a mechanistic model for induced polarization in frequency domain, that incorporates both grain and membrane polarization and uses a non-linear mixing rule to combine the contribution of water, air and solid grains. The model is tested on two different lab experimental datasets. Different spectra characteristics can be understood and described by distinguished porous media behaviors.
For decades, bad practices in municipal and industrial waste management have had negative environ... more For decades, bad practices in municipal and industrial waste management have had negative environmental impacts, generating high health risks for people and the environment. The use of badly designed, not engineered, and not well-operated landfills has, around the world, produced a large number of potentially contaminated sites, for which there are urgent needs to assess the actual risk and to proceed, in case, with reclamation activities. One of these sites, an abandoned waste disposal site located near a Site of Community Importance on the central-eastern coast of Sardinia (Italy), is the subject of the case history described in this work. As a part of a multi-method geophysical characterisation, a frequency-domain electromagnetic (FDEM) mapping survey was carried out with the specific aim of detecting the presence of buried materials (waste) and of delineating the lateral extent of the landfill by identifying the electrical conductivity anomalies produced, for the most part, by t...
Abstract Noninvasive methods for the characterization of shallow subsurface have been used routin... more Abstract Noninvasive methods for the characterization of shallow subsurface have been used routinely for some 20–30 years. The growth in these methods has been driven by a variety of breakthroughs in the use of electrical, electromagnetic, and seismic methods, to mention only the most common techniques. Increasing field capabilities and computational power have yet to yield all their potential fruits. In this chapter, we introduce readers to the basic concepts of shallow subsurface methods. We guide them through some of the physical details and present a number of application examples all derived from our own experience, concerning both structural characterization and (fluid)-dynamic understanding of the shallow subsurface. Finally, we propose ideas concerning the future development of this wide and exciting discipline.
Environmental Science and Pollution Research, 2021
The remediation of petroleum-contaminated soil and groundwater is a challenging task. The petrole... more The remediation of petroleum-contaminated soil and groundwater is a challenging task. The petroleum hydrocarbons have a long persistence in both the vadose zone and in the aquifer and potentially represent secondary and residual sources of contamination. This is particularly evident in the presence of residual free-phase. Pump-and-treat is the most common hydrocarbon decontamination strategy. Besides, it acts primarily on the water dissolved phase and reduces concentrations of contaminants to an asymptotic trend. This study presents a case of enhanced light non-aqueous phase liquid (LNAPL) remediation monitored using noninvasive techniques. A pilot-scale field experiment was conducted through the injection of reagents into the subsoil to stimulate the desorption and the oxidation of residual hydrocarbons. Geophysical and groundwater monitoring during pilot testing controlled the effectiveness of the intervention, both in terms of product diffusion capacity and in terms of effective ...
Hydrogeological uniqueness and chemical-physical peculiarities guide the contamination dynamics a... more Hydrogeological uniqueness and chemical-physical peculiarities guide the contamination dynamics and decontamination mechanisms in the environmental arena. A single composite geodatabase, which integrates geological/hydrological, geophysical, and chemical data, acts as a “cockpit” in the definition of a conceptual model, design of a remediation strategy, implementation, near-real-time monitoring, and validation/revision of a pilot test, and monitoring full-scale interventions. The selected remediation strategy involves the creation of "reactive" zones capable of reducing the concentration of chlorinated solvents in groundwater through the combined action of adsorption on micrometric activated carbon, which is injected into the aquifer, and degradation of organic contaminants, stimulating the dechlorinating biological activity by the addition of an electron donor. The technology is verified through a pilot test, to evaluate the possibility of scaling up the process. The resu...
Previous studies have demonstrated the potential benefits of the complex conductivity (CC) imagin... more Previous studies have demonstrated the potential benefits of the complex conductivity (CC) imaging over electrical resistivity tomography for an improved delineation of hydrocarbon-impacted sites and accompanying biogeochemical processes. However, time-lapse CC field applications are still rare, in particular for measurements performed near anthropogenic structures such as buried pipes or tanks, which are typically present at contaminated sites. To fill this gap, we have developed CC imaging (CCI) results for monitoring data collected in Trecate (northwest Italy), a site impacted by a crude oil spill. Initial imaging results reveal only a poor correlation with seasonal variations of the groundwater table at the site (approximately 6 m). However, it is not clear to which extend such results are affected by anthropogenic structures present at the site. To address this, we performed a detailed analysis of the misfit between direct and reciprocal time-lapse differences. Based on this an...
Whether or not one can detect relict signatures of the past imprinted in current landscapes is a ... more Whether or not one can detect relict signatures of the past imprinted in current landscapes is a question of the utmost theoretical and practical relevance for meandering tidal channels, owing to their influence on the morphodynamic evolution of tidal landscapes, a critically fragile environment, especially in face of expected climatic changes. Unravelling the sedimentary patterns of ancient channels is an expensive process that usually requires high resolution sediment coring. Here we use a novel inversion process of multi-frequency electromagnetic measurements to reveal the signature and characterize the dynamics of a salt-marsh paleo-meander in the Venice Lagoon. We show that the ancient meander migrated laterally while vertically aggrading, developing a peculiar bar geometry which is less common in analogous fluvial meanders. The observed point-bar dynamics and the associated architectural geometry are consistent with remote sensing and borehole data and contrast with current as...
A problematic aspect characterizing field tracer tests monitored by hydrogeophysical methods, suc... more A problematic aspect characterizing field tracer tests monitored by hydrogeophysical methods, such as Electrical Resisitivity Tomography (ERT), is a correct definition of the initial distribution of the solute in the injection volume. An incomplete or erroneous knowledge of the initial conditions can in fact heavily affect the interpretation of the tests, typically resulting in large errors on the estimation of
In the framework of the Research Strategic Project Geo-Risks "Geological and hydrological pr... more In the framework of the Research Strategic Project Geo-Risks "Geological and hydrological processes: monitoring, modeling and impact in the North-East Italy", a seismic reflection survey and surface waves analysis were performed on the Mt. Toc landslide in the Vajont Valley, Italy. The aim of the geophysical measurements was to obtain a 2D geophysical model of the entire landslide body down to the sliding surface depth and the characterization of rock seismic velocities. Due to the critical environment, another aim of the project was also to explore the feasibility and limitations of these geophysical tools in large landslide studies. The seismic reflection survey was conducted along two lines: L1 and L2, that are 510 and 322 m long respectively, with a - 'Vibroseis' - operating in the vertical mode (P wave) and vertical geophones. L1 was also acquired with - 'Vibroseis' - in horizontal mode (SH) and horizontal geophones. The Frequency Time Analysis of surf...
The Science of the total environment, Jan 15, 2015
Water scarcity is a serious environmental problem in many European regions, and will likely incre... more Water scarcity is a serious environmental problem in many European regions, and will likely increase in the near future as a consequence of increased abstraction and climate change. Water scarcity exacerbates the effects of multiple stressors, and thus results in decreased water quality. It impacts river ecosystems, threatens the services they provide, and it will force managers and policy-makers to change their current practices. The EU-FP7 project GLOBAQUA aims at identifying the prevalence, interaction and linkages between stressors, and to assess their effects on the chemical and ecological status of freshwater ecosystems in order to improve water management practice and policies. GLOBAQUA assembles a multidisciplinary team of 21 European plus 2 non-European scientific institutions, as well as water authorities and river basin managers. The project includes experts in hydrology, chemistry, biology, geomorphology, modelling, socio-economics, governance science, knowledge brokerag...
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