A Screening Model to Predict Entrapped LNAPL Depletion

Teramoto, Elias Hideo; Chang, Hung Kiang

doi:10.3390/w12020334

Cited by 8 publications

(3 citation statements)

References 52 publications

(87 reference statements)

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“…One of the principal sources of contamination of the subsoil and underground waters is the accidental release of petroleum-based fuels from storage tanks or pipelines [11,55]. These highly toxic compounds tend to enter the environment through spills or leaks and then spread rapidly.…”

Section: Discussionmentioning

confidence: 99%

Groundwater Contamination by Gas Stations in Two Eastern Amazonian Towns (Northern Brazil)

Chira,

Mendes,

Ferrari

et al. 2024

Applied Sciences

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The present study analyzed the presence of the principal volatile compounds of the BTEX type (benzene, toluene, ethylbenzene, and xylene [o-, m- and p-xylene]) in samples of water from wells located at residences and gas stations in two Amazonian towns—Tracuateua and Augusto Corrêa—in the Amazon region of northern Brazil. This innovative study is extremely relevant to the Amazonian towns surveyed, given that they lack systematic policies for the environmental control of gas stations and any municipal regulations on the quality of water destined for human consumption. A combination of mass spectrometry (MS) and gas chromatography (CG) techniques was applied to analyze these contaminants in 150 samples of local groundwater collected between 2020 and 2024. One of the four BTEX compounds (toluene) was identified in seven of the samples collected (4.66% of the total) at concentrations of 0.14–2.10 µg L−1. The concentrations of contaminants were low, in general. None of the water samples analyzed here presented any critical loss of water quality for human consumption according to the Brazilian legislation concerning BTEX concentrations. Neither of the two towns surveyed in the present study has remediation programs for environmental contamination. The GC-MS approach produced satisfactory results for the assessment of the contamination of underground water reserves by gas stations in both study towns. Further research (e.g., geophysical methods) will be necessary to determine the source of the contamination and its connection with the levels of toluene identified in the underground water sampled in these Amazonian towns.

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Section: Discussionmentioning

confidence: 99%

Groundwater Contamination by Gas Stations in Two Eastern Amazonian Towns (Northern Brazil)

Chira,

Mendes,

Ferrari

et al. 2024

Applied Sciences

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“…BTEX contamination in groundwater has garnered significant attention due to its toxicity and carcinogenic properties, which pose substantial risks to human health [21][22][23][24]. One of the primary sources of subsoil and groundwater contamination is the accidental release of petroleum-derived fuels from storage tanks or transport pipelines [19,25]. When such leaks or spills involve a sufficient quantity of fuel, they can migrate downward through the unsaturated zone and eventually reach the groundwater [26].…”

Section: Introduction and Objectivesmentioning

confidence: 99%

Environmental Assessment of Soil and Groundwater Pollution by BTEX Leaching in Valencia Region (Spain)

Rodrigo-Ilarri,

Rodrigo-Clavero,

Capilla

et al. 2023

Water

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The impact of hydrocarbon spills in the unsaturated zone is a significant environmental concern, particularly in locations where contamination arises from leaks in underground fuel storage tanks (USTs). This paper presents the outcomes achieved through the utilization of VLEACH, a finite-difference numerical model, to assess the concentrations of organic contaminants in the solid, liquid, and gas phases within the vadose zone. Additionally, it evaluates the mass transfer of pollutants to the aquifer as part of an environmental assessment for the placement of a forthcoming service station. The study encompasses an analysis of 18 scenarios under realistic conditions based on actual field data. These scenarios were constructed, taking into account various factors, including the nature of the leak (one-time or permanent), the depth of the phreatic level, and the soil conditions and properties. The results highlight the potential environmental consequences of a permanent leak as compared to those resulting from a specific accident. The findings further emphasize the substantial influence of soil moisture on transport phenomena within the vadose zone. Variations in soil moisture significantly alter hydraulic conductivity, impact magnitudes, transport velocities, and even the predominant transport mechanism. Consequently, precise delineation of soil moisture becomes a crucial parameter in such simulations. Additionally, it has been observed that each component of BTEX (benzene, toluene, ethylbenzene, and xylene) experiences varying transport velocities through the vadose zone. Benzene, having a greater propensity to concentrate in the liquid and gas phases, exhibits the swiftest movement through the vadose zone. The detection of benzene in aquifers can serve as an indicator of the potential future arrival of the remaining BTEX compounds.

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“…The immobile hydrocarbon, trapped in the pores, keeps its competition with soil water. Interaction of retained hydrocarbon with water generates the partial dissolution of its constituents, mainly a group of aromatic organic chemical compounds called BTEX (benzene, toluene, ethylbenzene and xylene) [6]. The dissolved phase is highly mobile, and it is responsible for the transport of contaminant over long distances from the source [7,8].…”

Section: Introductionmentioning

confidence: 99%

Assessment of groundwater contamination risk by BTEX from residual fuel soil phase

2021

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The aim of this work is to assess the risk of groundwater contamination associated with BTEX dissolution from fuels as a residual phase. Numerical simulations of sixty scenarios were carried out with the software HYDRUS 2D/3D. Groundwater contamination risk was analyzed given the combination of different porous media textures (silt loam, sandy loam and clay), water fluxes (0.5%, 1% or 3% Rainfall), water table depths (1.5, 2.5, 5 or 8 m below ground surface) and biodegradation rate (active or null). Risk was calculated comparing leachate concentrations to the aquifer and limits established by an international guideline for human drinking water. In all cases, benzene and toluene had the highest mobility in the dissolved phase. Contrary, xylene and ethylbenzene tended to concentrate close to the source zone. These two compounds predominantly concentrated in the solid phase. Calculated risk was proportional to the water flux rate and inversely proportional to the unsaturated thickness. Without biodegradation, in fine-grained sediments risk was very high for shallow aquifers (> 1.5 m depth) and moderate or low for deeper aquifers. However, in sandy loam sediments risk was classified as very high for aquifers up to 8 m deep. When biodegradation was considered, leached concentrations were greatly reduced in the three textures. BTEX concentration in Bahía Blanca City´s aquifer showed acceptable agreement with simulated scenarios. The most sensitive parameters to model results were biodegradation > foc > water table depth > Ks. This study is important for assessing the risks and developing management strategies for fuel contaminated sites.

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A Screening Model to Predict Entrapped LNAPL Depletion

Cited by 8 publications

References 52 publications

Groundwater Contamination by Gas Stations in Two Eastern Amazonian Towns (Northern Brazil)

Groundwater Contamination by Gas Stations in Two Eastern Amazonian Towns (Northern Brazil)

Environmental Assessment of Soil and Groundwater Pollution by BTEX Leaching in Valencia Region (Spain)

Assessment of groundwater contamination risk by BTEX from residual fuel soil phase

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