Analytical modeling of degradation product partitioning kinetics in source zones containing entrapped DNAPL

Ramsburg, C. Andrew; Christ, John A.; Douglas, Scott R.; Boroumand, A.

doi:10.1029/2010wr009958

Cited by 9 publications

(9 citation statements)

References 61 publications

(127 reference statements)

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“…Values of the partition coefficient employed in these simulations were 4.20, 17.4, and 149 L aq /L NAPL for 1-pentanol, 1-hexanol, and 2-octanol, respectively, at 22.0±0.1°C. Note that linear driving force and dual diffusion models produce nearly identical results, the pore volume scale changes for each panel, and the normalized concentration scale changes for panel d. a Calculated using correlation of Ramsburg et al (2011).…”

Section: Column Experimentsmentioning

confidence: 99%

Section: Dual Diffusionmentioning

confidence: 99%

“…Schnaar and Brusseau (2005) and Ramsburg et al (2011) developed regressions that relate an effective DNAPL drop radius to the saturation and textural characteristics of the granular medium. The correlation of Ramsburg et al (2011) is employed herein to estimate ganglia size. To convert from f k to kˆ, the model assumes that all of the DNAPL surface area is accessible to the tracer, and that this surface area can be calculated assuming a uniform distribution of spherical droplets:…”

Section: Dual Diffusionmentioning

confidence: 99%

“…For the model results presented herein, the lumped mass transfer coefficient was evaluated using an empirical correlation developed for NAPL dissolution (Powers et al, 1992). Ramsburg et al (2011) have recently shown that the Powers et al (1992) and Imhoff et al (1994) correlations are capable of, and offer similar performance when, describing the mass transfer of chlorinated solvent degradation products within columns containing uniform saturations of DNAPL.…”

Section: Linear Driving Forcementioning

confidence: 99%

“…following methods described in . The 45-50 mesh Ottawa Sand (see Section II.2.2.1) was selected to generate TCE-DNAPL ganglia (dyed with Oil-Red-O) that exist primarily as singlets (Schnaar and Brusseau, 2005;Ramsburg et al, 2011). Conservative, nonreactive tracer tests were conducted pre and post TCE-DNAPL emplacement to estimate dispersivity and confirm the uniformity of the emplaced DNAPL distribution .…”

Section: Ii222 Experimental Set Upmentioning

confidence: 99%

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Metric Identification and Protocol Development for Characterizing DNAPL Source Zone Architecture and Associated Plume Response

Abriola¹,

Miller²,

Pennell³

et al. 2013

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2. REPORT TYPE SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENT SUPPLEMENTARY NOTES ABSTRACTThe overarching goal of this research is to develop and demonstrate a comprehensive approach for field characterization of DNAPL source zones which quantifies the key features that control plume response. Here the intent is to integrate targeted (local-scale) in situ tests with transect-based observations of downstream contaminant flux or concentration and information on subsurface geologic variability. To address its primary goal, the research encompasses the following specific objectives: (1) identification of the most information rich metrics for linking NAPL architecture to plume response; (2) development and refinement of in situ test methods and modeling tools that can be used to quantify identified metrics in targeted regions of the source zone; (3) integration of these metrics and tools with current machine learning characterization methods for an overall source zone assessment protocol; and (4) development of simplified models for prediction of plume response. The research approach integrates batch, column and aquifer cell experiments with mathematical modeling and data processing tools to identify and quantify features of the DNAPL architecture controlling down gradient plume response. SUBJECT TERMSField characterization; Metric identification; DNAPL; SECURITY CLASSIFICATION OF:No classified information

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Section: Column Experimentsmentioning

confidence: 99%

Section: Dual Diffusionmentioning

confidence: 99%

Section: Dual Diffusionmentioning

confidence: 99%

Section: Linear Driving Forcementioning

confidence: 99%

Section: Ii222 Experimental Set Upmentioning

confidence: 99%

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Metric Identification and Protocol Development for Characterizing DNAPL Source Zone Architecture and Associated Plume Response

Abriola¹,

Miller²,

Pennell³

et al. 2013

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On the upscaling of mass transfer rate expressions for interpretation of source zone partitioning tracer tests

Boroumand

Abriola

2015

Water Resources Research

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Analysis of partitioning tracer tests conducted in dense nonaqueous phase liquid (DNAPL) source zones relies on conceptual models that describe mass exchange between the DNAPL and aqueous phases. Such analysis, however, is complicated by the complex distribution of entrapped DNAPL mass and formation heterogeneity. Due to parameter uncertainty in heterogeneous regions and the desire to reduce model complexity, the effect of mass transfer limitations is often neglected, and an equilibrium-based model is typically used to interpret test results. This work explores the consequences of that simplifying assumption on test data interpretation and develops an alternative upscaled modeling approach to quantify effective mass transfer rates. To this end, a series of partitioning tracer tests is numerically simulated in heterogeneous two-dimensional PCE-DNAPL source zones, representative of a range of hydraulic conductivity and DNAPL mass distribution characteristics. The effective mass transfer coefficient corresponding to each test is determined by fitting an upscaled model to the simulated data, and regression analysis is performed to explore the correlation between various source zone metrics and the effective mass transfer coefficient. Results suggest that vertical DNAPL spreading, Reynolds number, pool fraction, and the effective organic phase saturation are the most significant parameters controlling tracer partitioning rates. Finally, a correlation for prediction of the effective (upscaled) mass transfer coefficient is proposed and verified using existing experimental data. The developed upscaled model incorporates the influence of physical heterogeneity on the rate of tracer partitioning and, thus, can be used for the estimation of source zone mass distribution characteristics from tracer test results.

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Organic contaminant transport and fate in the subsurface: Evolution of knowledge and understanding

Essaid

Bekins

Cozzarelli

2015

Water Resources Research

147

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Toxic organic contaminants may enter the subsurface as slightly soluble and volatile nonaqueous phase liquids (NAPLs) or as dissolved solutes resulting in contaminant plumes emanating from the source zone. A large body of research published in Water Resources Research has been devoted to characterizing and understanding processes controlling the transport and fate of these organic contaminants and the effectiveness of natural attenuation, bioremediation, and other remedial technologies. These contributions include studies of NAPL flow, entrapment, and interphase mass transfer that have advanced from the analysis of simple systems with uniform properties and equilibrium contaminant phase partitioning to complex systems with pore-scale and macroscale heterogeneity and rate-limited interphase mass transfer. Understanding of the fate of dissolved organic plumes has advanced from when biodegradation was thought to require oxygen to recognition of the importance of anaerobic biodegradation, multiple redox zones, microbial enzyme kinetics, and mixing of organic contaminants and electron acceptors at plume fringes. Challenges remain in understanding the impacts of physical, chemical, biological, and hydrogeological heterogeneity, pore-scale interactions, and mixing on the fate of organic contaminants. Further effort is needed to successfully incorporate these processes into field-scale predictions of transport and fate. Regulations have greatly reduced the frequency of new point-source contamination problems; however, remediation at many legacy plumes remains challenging. A number of fields of current relevance are benefiting from research advances from point-source contaminant research. These include geologic carbon sequestration, nonpoint-source contamination, aquifer storage and recovery, the fate of contaminants from oil and gas development, and enhanced bioremediation.

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Analytical modeling of degradation product partitioning kinetics in source zones containing entrapped DNAPL

Cited by 9 publications

References 61 publications

Metric Identification and Protocol Development for Characterizing DNAPL Source Zone Architecture and Associated Plume Response

Metric Identification and Protocol Development for Characterizing DNAPL Source Zone Architecture and Associated Plume Response

On the upscaling of mass transfer rate expressions for interpretation of source zone partitioning tracer tests

Organic contaminant transport and fate in the subsurface: Evolution of knowledge and understanding

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