Geophysical and geochemical characterisation of a site impacted by hydrocarbon contamination undergoing biodegradation

Abstract

Hydrocarbon contamination, which can alter the physiochemical and biological properties of the subsurface, can be monitored by using geochemical analyses and integrated geophysical techniques. Electrical resistivity tomography, induced polarization, ground‐penetrating radar, and self‐potential methods were used in this work to characterise the hydrocarbon contamination and investigate the geoelectrical properties of a site impacted by an aged hydrocarbon plume. Throughout the investigation, geoelectrical measurements supported the conductive plume model and consistently recorded low‐resistivity anomalies and high‐chargeability values in the contaminated aquifer. Furthermore, the low‐resistivity anomalies were found to be coincident with regions of ground‐penetrating radar attenuated reflections and significant negative self‐potential anomalies associated with oxidation–reduction processes. These findings were supported by the geochemical measurements, which revealed depleted concentrations of terminal electron acceptors (TEAs) and elevated amounts of ions and total dissolved solids, which could be attributed to bacterial biodegradation of hydrocarbons. The study showed that biological alterations of hydrocarbon‐induced subtle changes in the pore water biogeochemistry, which consequently modified the geophysical properties of the contaminated sediments. Based on these observations, the extent of groundwater contamination was delineated according to the geophysical contrast between the contaminated and clean zones. The combination of different geophysical methods constrained by geochemical point measurements provided insight on the different processes that might have modified the soil and groundwater biogeochemical properties.

The Assessment of Relative Permittivity on Diesel Vapour in the Moisture Content of Terap Red Soil by Ground Penetrating Radar

“…This finding was supported by Abbas et al 32 and Cassidy 45 and in the evaluation of LNAPLs from kerosene, petrol oil and benzene using GPR signal attenuation from hydrocarbon evaporation process that contributed to the variation of relative permittivity. However, Shao et al 13 were argued in studied on coarse quartz sands (porosity: 46.44%), that time travel of GPR reflected wave was increased due with decrease in the water level due to water evaporation which leads to relative permittivity decreased.…”

“…Furthermore, the non-uniform proliferation of hydrocarbon was illustrated by Mansi et al, 12 Bano et al 19 and Abbas et al, 32 which was followed by the production of a new hyperbolic reflection pattern in the hour 19 at a horizontal length between 0.6 and 1.9 m and an approximate depth of 1.0 m. An increasing pattern could be seen with the increase in the wide area, followed by an increase in the range of reflection pattern after 19 hours of diesel migration leakage. A similar result was reported by Klazinga et al 30 and Abbas et al 32 in the monitoring of benzene and methane in a sandy aquifer, after a long period of surveillance, permittivity contrast was formed within the saturated zone resulting in a strong reflection in the GPR profile. To explain the reflection polarity change, it was hypothesised that the fragmentation of water and air regime from soil pores led to enhanced surface runoff and reduced soil moisture.…”

Evaluation of the contamination of the subsurface and groundwater by monoaromatic hydrocarbons in an eastern Amazonian town in northern Brazil

“…Different geophysical techniques (e.g., electrical resistivity tomography (ERT), induced polarization (IP), electromagnetic induction (EMI), magnetic, ground penetrating radar (GPR), and spontaneous potential, SP) have been applied increasingly to the investigation, description, and monitoring of areas contaminated by hydrocarbons (Biosca et al 2020;Abbas et al 2018;Subba Rao and Chandrashekhar 2014;Aal et al 2001).…”

Magnetometric resistivity tomography using chaos polynomial expansion

“…Jardani et al 2006;Ezersky et al 2013;Redhaounia et al 2016), the delineation of a contaminated aquifer (e.g. Abbas et al 2018;Grünhut et al 2018;Liao et al 2018) and the mapping of sea intrusion in coastal areas (e.g. George et al 2004;De Franco et al 2009;Kazakis et al 2016).…”