Flow field dynamics and high ethanol content in gasohol blends enhance BTEX migration and biodegradation in groundwater

Rama, Fabrizio; Ramos, Débora Toledo; Müller, Juliana Braun; Corseuil, Henry Xavier; Miotliński, Konrad

doi:10.1016/j.jconhyd.2019.01.003

Cited by 24 publications

(27 citation statements)

References 48 publications

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“…Different parcels of the same field site with the same relatively uniform microbial ecology were polluted and cleaned-up over the last 15 years (Figure 1) [9][10][11][12][13][14][15][16][17] . A range of pollution events was used including pollution by gasoline-ethanol (E10, E25, E85), biodiesel (B100) and dieselbiodiesel blends (B20).…”

Section: Methodsmentioning

confidence: 99%

“…A peristaltic pump and Teflon tubing were used to collect groundwater samples into capped sterile vials without headspace. BTEX, ethanol and methane were analyzed by gas chromatography using a GC HP model 6890 II equipped with a flame ionization detector (FID), HP 1 capillary column (30 cm, 0.53 mm, 2.65 mm) and HP 7694 headspace auto sampler, as described elsewhere 17 . PAH were extracted from groundwater using solid phase SPE cartridges, according to EPA method 525.2, and measured by gas chromatography (HP model 6890 II with a flame ionization detector (FID) and HP-5 capillary column), as described elsewhere 11 .…”

Section: Groundwater Chemical Analysismentioning

confidence: 99%

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Back to the Wild: Polluted Site Remediation and Biosphere Resilience

Vogel

2021

Preprint

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Worldwide efforts to depollute environments altered by human industrial activity have begun to produce an ever-increasing number of "clean" sites. "Clean" is defined by local regulatory processes and often responds to low compound concentrations or risk evaluations. Yet, these sites have been critically derailed from their historical biological activity by both the pollution event and the clean-up technology. This work explored the impact of contaminated (and remediated) sites on local microbial ecosystems. Different parcels of the same field site with the same relatively uniform microbial ecology were polluted and cleaned-up over the last 15 years. The statistical evaluation of the perturbation described changes to the local ecosystem that went back to the original baseline microbial composition although the pollution sources and the clean-up technologies affected the rate of return to the pre-disturbed condition. This rate reflected the intensity of the clean-up treatments. The role played by microbial communities on ecosystem maintenance and mitigation of pollution events lays the groundwork for predicting the microbial community responses to perturbations and the ability to reassert themselves. Predictions of ecosystem response to anthropogenic impacts could support decision-making on environmental management strategies for contaminated sites clean-up, depending on the ecosystem services desired to maintain or the risk posed to sensitive receptors.

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Section: Methodsmentioning

confidence: 99%

Section: Groundwater Chemical Analysismentioning

confidence: 99%

Back to the Wild: Polluted Site Remediation and Biosphere Resilience

Vogel

2021

Preprint

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“…The details of the experiments are summarized in the electronic supplementary material- Table S1 in the electronic supplementary material (ESM). In this area, groundwater flow velocity and transient processes consistently contribute to plume spreading and solute migration, requiring a deep characterization of spatial and temporal variations in the hydraulic regime (Rama et al 2019).…”

Section: Field Experiments Site Characterization and Monitoringmentioning

confidence: 99%

“…first-order decay and linear diffusion) in a highly variable flow field with density and viscosity gradient effects. A 3D domain defined a triangular portion among piezometers PE03, PE02 and PM01, in which the MNA_E85 experiment was developed (Rama et al 2019). Also in this case, model parameterization was based on specific field conditions.…”

Section: Model Dmentioning

confidence: 99%

“…Evolution of total dissolved mass of ethanol. Comparison of model D simulation, both steady boundary conditions (BCs; blue solid line) and transient BCs (red solid line), versus observed values (black dots) of total dissolved mass within the area of MNA_E85 field experiment(Rama et al 2019) Variation of plume migration. Comparison of conservative plumes dispersion after 490 days from the spill with a transient and b steady head boundary conditions.…”

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confidence: 99%

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Multiple-step numerical modeling to assist aquifer characterization: a case study from the south of Brazil

Rama

Miotliński

2020

Hydrogeol J

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Management of coastal groundwater must take account of the complex hydrological processes and uncertainties associated with this environment. Regular evaluation of mechanisms, parameters and boundary conditions is required to understand groundwater flow and to develop a robust conceptual model. In certain conditions, as in tropical regions, due to the high intensity and variability of natural drivers (precipitation, evapotranspiration), a comprehensive hydrogeological characterization may be needed. Data on transient recharge, tide-driven fluctuations of groundwater receptors (seas, rivers) and the activation status of drainage networks may need to be updated recurrently, as they likely influence groundwater balance. Numerical models are applied at various phases of a hydrogeological investigation to elucidate preliminary conceptual models and to guide the field characterization. Those models provide a quantitative framework for synthesizing field information and verifying mechanisms readily contributing to a cost-effective decision-making process. This article presents a systematic hydrogeological characterization of a coastal basin in a tropical region of southern Brazil that is affected by intensive precipitation and ocean tides; precipitation is the main process driving groundwater flow, although head variations at the boundaries affect a spatiotemporal distribution of the water table. A set of numerical experiments is deployed to test the understanding of natural processes and to assist additional field campaigns. The hierarchy of hydrogeological processes is evaluated over different scales, to eliminate less sensitive mechanisms. By presenting the detailed setup information on model development, the applications are demonstrated and limitations are discussed in light of the available field data and specific research objectives.

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Long‐term evaluation of hydrocarbon degradation rates within the source zone under natural and enhanced attenuation for site closure purposes

Schneider,

Bortolassi,

Soriano

et al. 2024

Remediation Journal

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Despite addressing the cleanup of petroleum hydrocarbon contamination plumes in groundwater, challenges with site closure persist due to the ongoing long‐term contaminant release from source zones. Thus, source zone monitoring even in the presence of residual light nonaqueous‐phase liquid (LNAPL) is mandated by many countries' regulatory agencies before site closure. In this study, four independent controlled‐release sites, each containing a particular fraction of ethanol in gasoline, that is, 10%, 24%, 25%, and 85% (v/v), were subjected to monitored natural attenuation (MNA) alone (E24 and E85), and with nitrate (E25) and sulfate (E10) biostimulation at the vicinity of the source zone. To the best of the authors' knowledge, this is the longest controlled gasohol release monitoring study performed to date at the source zone for site closure (nearly 18 years of monitoring). Both natural source zone depletion and biostimulation were found to reduce benzene concentrations to acceptable remediation target levels according to environmental regulatory councils. Benzene biodegradation rates (λs) were one order of magnitude higher than those reported in the literature for diluted concentrations in groundwater plumes. The decay rate of benzene varied between 0.45 and 1.75/year and was strongly influenced by the mass of ethanol. Compared to biostimulation with nitrate (half‐life of 1.52 years), MNA alone resulted in faster benzene removal rates (half‐life of 0.96 years). Anaerobic biostimulation with sulfate had negligible effects on benzene, toluene, ethylbenzene, and xylene (o‐, m‐, and p‐xylene [BTEX]) biodegradation compared to natural attenuation alone. The highest ethanol concentration (E85) led to faster benzene removal (with a half‐life of 0.40 years), which was even higher than MNA under lower ethanol concentrations (E24). Benzene half‐life was 2.2‐fold slower in the site with the lowest ethanol (E10) compared to E85, indicating that the negative effects of ethanol on BTEX biodegradation appeared to be short‐lived and may need to be re‐evaluated over the long term. Benzene decay rates were approximately six times slower in the source zone than the rates obtained for groundwater plumes, emphasizing the importance of targeting the LNAPL after plume retreat. The study's findings can assist practitioners in better predicting the lines of evidence for BTEX bioremediation and remediation cleanup times at a lower cost in the presence of ethanol, as well as providing guidance for determining whether biostimulation is necessary to expedite source zone remediation for site closure.

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Flow field dynamics and high ethanol content in gasohol blends enhance BTEX migration and biodegradation in groundwater

Cited by 24 publications

References 48 publications

Back to the Wild: Polluted Site Remediation and Biosphere Resilience

Back to the Wild: Polluted Site Remediation and Biosphere Resilience

Multiple-step numerical modeling to assist aquifer characterization: a case study from the south of Brazil

Long‐term evaluation of hydrocarbon degradation rates within the source zone under natural and enhanced attenuation for site closure purposes

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