Temporal geophysical signatures from contaminant-mass remediation

Geophysics ◽  
2009 ◽  
Vol 74 (4) ◽  
pp. B113-B123 ◽  
Author(s):  
Vukenkeng Che-Alota ◽  
Estella A. Atekwana ◽  
Eliot A. Atekwana ◽  
William A. Sauck ◽  
D. Dale Werkema
Keyword(s):  
Electrical Conductivity ◽  
Hydrocarbon Biodegradation ◽  
Vapor Extraction ◽  
Bulk Electrical Conductivity ◽  
Geophysical Surveys ◽  
Biogeochemical Transformations ◽  
Ground Penetrating ◽  
Self Potential ◽  
Sp Anomaly ◽  
Contaminated Area

We have previously documented changes in bulk electrical conductivity, self-potential (SP), and ground-penetrating-radar (GPR) reflections in a field setting caused by biogeochemical transformations of hydrocarbon-contaminated media. These transformations are associated with hydrocarbon biodegradation. The results of surface geophysical surveys acquired in 1996, 2003, and 2007 document changes in geophysical signatures associated with removing hydrocarbon mass in the contaminated zone. Initial investigations in 1996 showed that relative to background, the contaminated area was characterized by higher bulk electrical conductivity, positive SP anomaly, and attenuated GPR reflections. Repeated surveys in 2003 and 2007 over the contaminated area showed that in 2007, the bulk electrical conductivityhad reverted to near-background conditions, the positive SP anomaly became more negative, and the zone of attenuated GPR reflections showed increased signal strength. Removal of hydrocarbon mass in the vadose zone over the plume by a soil vapor-extraction system installed in 2001 was primarily responsible for the changing geophysical responses. Although chemical data from groundwater showed a [Formula: see text]-thick con-ductive plume in 2007, the plume was not imaged by elec-trical resistivity. Forward modeling suggests that apparent bulk electrical conductivity of the saturated zone plume has to be three to five times higher than background values to be imaged by electrical resistivity. We suggest that removing hydrocarbon-contaminant-mass reduction by natural or engineered bioremediation can be imaged effectively by temporal geophysical surveys.

scholarly journals Mapping the Pollution Plume Using the Self-Potential Geophysical Method: Case of Oum Azza Landfill, Rabat, Morocco

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 961
Author(s):  
Meryem Touzani ◽  
Ismail Mohsine ◽  
Jamila Ouardi ◽  
Ilias Kacimi ◽  
Moad Morarech ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Water Table ◽  
Soil Surface ◽  
The Self ◽  
Drainage Network ◽  
Geophysical Method ◽  
Direct Measurements ◽  
Sandy Material ◽  
The City ◽  
Self Potential

The main landfill in the city of Rabat (Morocco) is based on sandy material containing the shallow Mio-Pliocene aquifer. The presence of a pollution plume is likely, but its extent is not known. Measurements of spontaneous potential (SP) from the soil surface were cross-referenced with direct measurements of the water table and leachates (pH, redox potential, electrical conductivity) according to the available accesses, as well as with an analysis of the landscape and the water table flows. With a few precautions during data acquisition on this resistive terrain, the results made it possible to separate the electrokinetic (~30%) and electrochemical (~70%) components responsible for the range of potentials observed (70 mV). The plume is detected in the hydrogeological downstream of the discharge, but is captured by the natural drainage network and does not extend further under the hills.

scholarly journals Implications of Self-Potential Distribution for Groundwater Flow System in a Nonvolcanic Mountain Slope

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Tada-nori Goto ◽  
Kazuya Kondo ◽  
Rina Ito ◽  
Keisuke Esaki ◽  
Yasuo Oouchi ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
General Trend ◽  
Flow System ◽  
Ground Surface ◽  
Mountain Slope ◽  
Infiltration Process ◽  
Groundwater Flow System ◽  
Self Potential ◽  
Sp Anomaly ◽  
Fft Analysis

Self-potential (SP) measurements were conducted at Mt. Tsukuba, Japan, which is a nonvolcanic mountain, to infer groundwater flow system in the mountain. Survey routes were set around the northern slope, and the reliability of observed SP anomaly was checked by using SP values along parallel survey routes; the error was almost within 10 mV. The FFT analysis of the spatial SP distribution allows us a separation of raw data into two components with shorter and longer wavelength. In the shorter (altitudinal) wavelength than ∼200 meters, several positive SP peaks of more than 100 mV in magnitude are present, which indicate shallow perched water discharges along the slope. In the regional SP pattern of longer wavelength, there are two major perturbations from the general trend reflecting the topographic effect. By comparing the SP and hydrological data, the perturbation around the foothill is interpreted to be caused by heterogeneous infiltration at the ground surface. The perturbation around the summit is also interpreted to be caused by heterogeneous infiltration process, based on a simplified numerical modeling of SP. As a result, the SP pattern is well explained by groundwater flow and infiltration processes. Thus, SP data is thought to be very useful for understanding of groundwater flow system on a mountain scale.

Shallow Magnetic Induction Measurements for Delineating Near-Surface Hot Groundwater Sources in Alaskan Geothermal Areas

1983 ◽  
Vol 105 (2) ◽  
pp. 156-161 ◽  
Author(s):  
T. E. Osterkamp ◽  
K. Kawasaki ◽  
J. P. Gosink
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Induction ◽  
Hot Springs ◽  
Measured Temperature ◽  
Conductivity Data ◽  
Induction Method ◽  
Near Surface ◽  
Saline Groundwater ◽  
Geophysical Surveys ◽  
Conductivity Anomalies

Variations in the electrical conductivity of a soil and water system with temperature and salt concentration suggest that a soil containing hot and/or saline groundwater may be expected to have a higher conductivity compared to a cooler and/or less saline system. Temperature and conductivity surveys were carried out at Pilgrim Springs, on the Seward Peninsula, and at Chena Hot Springs, near Fairbanks, to test the use of a magnetic induction method (which measures electrical conductivity) for delineating near-surface hot groundwater sources in geothermal areas surrounded by permafrost. Comparison of the temperature data and conductivity data from these surveys demonstrates that the conductivity anomalies, as measured by the magnetic induction method, can be used to define the precise location of hot groundwater sources in these geothermal areas with the higher temperatures correlating with higher values of conductivity. Magnetic induction measurements of conductivity can also be used to define the lateral extent of the thawed geothermal areas (used for calculating the stored energy) in permafrost terrain. The utility of these magnetic induction measurements of conductivity for reconnaissance geophysical surveys of geothermal areas is that a much greater density of data can be obtained in a shorter time in comparison with shallow temperature measurements. In addition, it is simpler, cheaper and easier (physically) to obtain the data. While conductivity anomalies can result from other than hot and/or saline groundwater, these conductivity data, when coupled with a few measured temperature profiles and groundwater samples, should result in reliable reconnaissance level geophysical surveys in Alaskan geothermal areas.

Electrical Conductivity of Agricultural Drainage Water in Iowa

2017 ◽  
Vol 33 (3) ◽  
pp. 369-378 ◽  
Author(s):  
Brett A Zimmerman ◽  
Amy L Kaleita
Keyword(s):  
Electrical Conductivity ◽  
Environmental Conditions ◽  
Major Ions ◽  
Ionic Composition ◽  
Field Investigation ◽  
Drainage Water ◽  
Specific Electrical Conductivity ◽  
Agricultural Drainage ◽  
Bulk Electrical Conductivity ◽  
Drainage Waters

Abstract. Assessing the effectiveness of management strategies to reduce agricultural nutrient efflux is hampered by the lack of affordable, continuous monitoring systems. Generalized water quality monitoring is possible using electrical conductivity. However environmental conditions can influence the ionic ratios, resulting in misinterpretations of established electrical conductivity and ionic composition relationships. Here we characterize specific electrical conductivity (k25) of agricultural drainage waters to define these environmental conditions and dissolved constituents that contribute to k25. A field investigation revealed that the magnitude of measured k25 varied from 370 to 760 µS cm-1. Statistical analysis indicated that variability in k25 was not correlated with drainage water pH, temperature, nor flow rate. While k25 was not significantly different among drainage waters from growing and post-growing season, significant results were observed for different cropping systems. Soybean plots in rotation with corn had significantly lower conductivities than those of corn plots in rotation with soybeans, continuous corn plots, and prairie plots. In addition to evaluating k25 variability, regression analysis was used to estimate the concentration of major ions in solution from measured k25. Regression results indicated that HCO3-, Ca2+, NO3-, Mg2+, Cl-, Na2+, SO42- were the major drainage constituents contributing to the bulk electrical conductivity. Calculated ionic molal conductivities of these analytes suggests that HCO3-, Ca2+, NO3-, and Mg2+ account for approximately 97% of the bulk electrical conductivity. Keywords: Electrical conductivity, Salinity, Subsurface drainage, Total dissolved solids.

Laboratory test of snow wetness influence on electrical conductivity measured with ground penetrating radar

2009 ◽  
Vol 40 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Nils Granlund ◽  
Angela Lundberg ◽  
James Feiccabrino ◽  
David Gustafsson
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Laboratory Test ◽  
Liquid Water ◽  
Ground Penetrating Radar ◽  
Wave Attenuation ◽  
Radar Measurements ◽  
Ground Penetrating ◽  
Radar Wave ◽  
The Relationship

Ground penetrating radar operated from helicopters or snowmobiles is used to determine snow water equivalent (SWE) for annual snowpacks from radar wave two-way travel time. However, presence of liquid water in a snowpack is known to decrease the radar wave velocity, which for a typical snowpack with 5% (by volume) liquid water can lead to an overestimation of SWE by about 20%. It would therefore be beneficial if radar measurements could also be used to determine snow wetness. Our approach is to use radar wave attenuation in the snowpack, which depends on electrical properties of snow (permittivity and conductivity) which in turn depend on snow wetness. The relationship between radar wave attenuation and these electrical properties can be derived theoretically, while the relationship between electrical permittivity and snow wetness follows a known empirical formula, which also includes snow density. Snow wetness can therefore be determined from radar wave attenuation if the relationship between electrical conductivity and snow wetness is also known. In a laboratory test, three sets of measurements were made on initially dry 1 m thick snowpacks. Snow wetness was controlled by stepwise addition of water between radar measurements, and a linear relationship between electrical conductivity and snow wetness was established.

scholarly journals Time-lapse cross-hole electrical resistivity tomography (CHERT) for monitoring seawater intrusion dynamics in a Mediterranean aquifer

2019 ◽  
Author(s):  
Andrea Palacios ◽  
Juan José Ledo ◽  
Niklas Linde ◽  
Linda Luquot ◽  
Fabian Bellmunt ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Resistivity ◽  
Seawater Intrusion ◽  
Electrical Resistivity Tomography ◽  
Low Cost ◽  
Heavy Rain ◽  
Time Lapse ◽  
Resistivity Tomography ◽  
Bulk Electrical Conductivity ◽  
Spatial Coverage

Abstract. Surface electrical resistivity tomography (ERT) is a widely used tool to study seawater intrusion (SWI). It is noninvasive and offers a high spatial coverage at a low cost, but it is strongly affected by decreasing resolution with depth. We conjecture that the use of CHERT (cross-hole ERT) can partly overcome these resolution limitations since the electrodes are placed at depth, which implies that the model resolution does not decrease in the zone of interest. The objective of this study is to evaluate the CHERT for imaging the SWI and monitoring its dynamics at the Argentona site, a well-instrumented field site of a coastal alluvial aquifer located 40 km NE of Barcelona. To do so, we installed permanent electrodes around boreholes attached to the PVC pipes to perform time-lapse monitoring of the SWI on a transect perpendicular to the coastline. After two years of monitoring, we observe variability of SWI at different time scales: (1) natural seasonal variations and aquifer salinization that we attribute to long-term drought and (2) short-term fluctuations due to sea storms or flooding in the nearby stream during heavy rain events. The spatial imaging of bulk electrical conductivity allows us to explain non-trivial salinity profiles in open boreholes (step-wise profiles really reflect the presence of fresh water at depth). By comparing CHERT results with traditional in situ measurements such as electrical conductivity of water samples and bulk electrical conductivity from induction logs, we conclude that CHERT is a reliable and cost-effective imaging tool for monitoring SWI dynamics.

scholarly journals Time-lapse cross-hole electrical resistivity tomography (CHERT) for monitoring seawater intrusion dynamics in a Mediterranean aquifer

2020 ◽  
Vol 24 (4) ◽  
pp. 2121-2139 ◽  
Author(s):  
Andrea Palacios ◽  
Juan José Ledo ◽  
Niklas Linde ◽  
Linda Luquot ◽  
Fabian Bellmunt ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Resistivity ◽  
Seawater Intrusion ◽  
Electrical Resistivity Tomography ◽  
Low Cost ◽  
Heavy Rain ◽  
Time Lapse ◽  
Resistivity Tomography ◽  
Bulk Electrical Conductivity ◽  
Spatial Coverage

Abstract. Surface electrical resistivity tomography (ERT) is a widely used tool to study seawater intrusion (SWI). It is noninvasive and offers a high spatial coverage at a low cost, but its imaging capabilities are strongly affected by decreasing resolution with depth. We conjecture that the use of CHERT (cross-hole ERT) can partly overcome these resolution limitations since the electrodes are placed at depth, which implies that the model resolution does not decrease at the depths of interest. The objective of this study is to test the CHERT for imaging the SWI and monitoring its dynamics at the Argentona site, a well-instrumented field site of a coastal alluvial aquifer located 40 km NE of Barcelona. To do so, we installed permanent electrodes around boreholes attached to the PVC pipes to perform time-lapse monitoring of the SWI on a transect perpendicular to the coastline. After 2 years of monitoring, we observe variability of SWI at different timescales: (1) natural seasonal variations and aquifer salinization that we attribute to long-term drought and (2) short-term fluctuations due to sea storms or flooding in the nearby stream during heavy rain events. The spatial imaging of bulk electrical conductivity allows us to explain non-monotonic salinity profiles in open boreholes (step-wise profiles really reflect the presence of freshwater at depth). By comparing CHERT results with traditional in situ measurements such as electrical conductivity of water samples and bulk electrical conductivity from induction logs, we conclude that CHERT is a reliable and cost-effective imaging tool for monitoring SWI dynamics.

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