Field, Laboratory and Modeling Evidence for Strong Attenuation of a Cr(VI) Plume in a Mudstone Aquifer Due to Matrix Diffusion and Reaction Processes
This study uses a combination of conventional and high resolution field and laboratory methods to investigate processes causing attenuation of a hexavalent chromium (<i>Cr</i>(<i>VI</i>)) plume in sedimentary bedrock at a former industrial facility. Groundwater plume <i>...
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| Format: | Article |
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MDPI AG
2021-03-01
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| Series: | Soil Systems |
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| Online Access: | https://www.mdpi.com/2571-8789/5/1/18 |
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| author | Steven Chapman Beth Parker Tom Al Richard Wilkin Diana Cutt Katherine Mishkin Shane Nelson |
| author_facet | Steven Chapman Beth Parker Tom Al Richard Wilkin Diana Cutt Katherine Mishkin Shane Nelson |
| author_sort | Steven Chapman |
| collection | DOAJ |
| description | This study uses a combination of conventional and high resolution field and laboratory methods to investigate processes causing attenuation of a hexavalent chromium (<i>Cr</i>(<i>VI</i>)) plume in sedimentary bedrock at a former industrial facility. Groundwater plume <i>Cr</i>(<i>VI</i>) concentrations decline by more than three orders of magnitude over a 900 m distance down gradient from the site. Internal plume concentrations generally exhibit stable to declining trends due to diffusive and reactive transport in the low permeability matrix as fluxes from the contamination source dissipate due to natural depletion processes and active remediation efforts. The strong attenuation is attributed to diffusion from mobile groundwater in fractures to immobile porewater in the rock matrix, and reactions causing transformation of aqueous <i>Cr</i>(<i>VI</i>) to low-solubility Cr(III) precipitates, confirmed by high spatial resolution rock matrix contaminant concentrations and comparisons with groundwater concentrations from multi-level sampling within the plume. Field characterization data for the fracture network and matrix properties were used to inform 2-D discrete-fracture matrix (DFM) numerical model simulations that quantify attenuation due to diffusion and reaction processes, which show consistency with field datasets, and provide insights regarding future plume conditions. The combination of field, laboratory and modeling evidence demonstrates effects of matrix diffusion and reaction processes causing strong attenuation of a <i>Cr</i>(<i>VI</i>) plume in a sedimentary bedrock aquifer. This approach has important implications for characterization of sites with <i>Cr</i>(<i>VI</i>) contamination for improved site conceptual models and remediation decision-making. |
| first_indexed | 2024-03-10T13:10:52Z |
| format | Article |
| id | doaj.art-5a07f5dc3dfa4754b3cd14ae042aecfb |
| institution | Directory Open Access Journal |
| issn | 2571-8789 |
| language | English |
| last_indexed | 2024-03-10T13:10:52Z |
| publishDate | 2021-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Soil Systems |
| spelling | doaj.art-5a07f5dc3dfa4754b3cd14ae042aecfb2023-11-21T10:46:28ZengMDPI AGSoil Systems2571-87892021-03-01511810.3390/soilsystems5010018Field, Laboratory and Modeling Evidence for Strong Attenuation of a Cr(VI) Plume in a Mudstone Aquifer Due to Matrix Diffusion and Reaction ProcessesSteven Chapman0Beth Parker1Tom Al2Richard Wilkin3Diana Cutt4Katherine Mishkin5Shane Nelson6G360 Institute for Groundwater Research, College of Engineering and Physical Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, CanadaG360 Institute for Groundwater Research, College of Engineering and Physical Sciences, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, CanadaDepartment of Earth and Environmental Sciences, University of Ottawa, 75 Laurier Ave. East, Ottawa, ON K1N 6N5, CanadaU.S. Environmental Protection Agency, Office of Research and Development (ORD), Center for Environmental Solutions & Emergency Response (CESER), Groundwater Characterization & Remediation Division, Robert S. Kerr Environmental Research Center, 919 Kerr Research Drive, Ada, OK 74820, USAU.S. Environmental Protection Agency, Region 2, 290 Broadway, New York, NY 10007-1866, USAU.S. Environmental Protection Agency, Region 3, 1650 Arch Street, Philadelphia, PA 19103, USAU.S. Environmental Protection Agency, Region 2, 290 Broadway, New York, NY 10007-1866, USAThis study uses a combination of conventional and high resolution field and laboratory methods to investigate processes causing attenuation of a hexavalent chromium (<i>Cr</i>(<i>VI</i>)) plume in sedimentary bedrock at a former industrial facility. Groundwater plume <i>Cr</i>(<i>VI</i>) concentrations decline by more than three orders of magnitude over a 900 m distance down gradient from the site. Internal plume concentrations generally exhibit stable to declining trends due to diffusive and reactive transport in the low permeability matrix as fluxes from the contamination source dissipate due to natural depletion processes and active remediation efforts. The strong attenuation is attributed to diffusion from mobile groundwater in fractures to immobile porewater in the rock matrix, and reactions causing transformation of aqueous <i>Cr</i>(<i>VI</i>) to low-solubility Cr(III) precipitates, confirmed by high spatial resolution rock matrix contaminant concentrations and comparisons with groundwater concentrations from multi-level sampling within the plume. Field characterization data for the fracture network and matrix properties were used to inform 2-D discrete-fracture matrix (DFM) numerical model simulations that quantify attenuation due to diffusion and reaction processes, which show consistency with field datasets, and provide insights regarding future plume conditions. The combination of field, laboratory and modeling evidence demonstrates effects of matrix diffusion and reaction processes causing strong attenuation of a <i>Cr</i>(<i>VI</i>) plume in a sedimentary bedrock aquifer. This approach has important implications for characterization of sites with <i>Cr</i>(<i>VI</i>) contamination for improved site conceptual models and remediation decision-making.https://www.mdpi.com/2571-8789/5/1/18hexavalent chromiumgroundwater plumematrix diffusionreactionattenuationsedimentary bedrock |
| spellingShingle | Steven Chapman Beth Parker Tom Al Richard Wilkin Diana Cutt Katherine Mishkin Shane Nelson Field, Laboratory and Modeling Evidence for Strong Attenuation of a Cr(VI) Plume in a Mudstone Aquifer Due to Matrix Diffusion and Reaction Processes Soil Systems hexavalent chromium groundwater plume matrix diffusion reaction attenuation sedimentary bedrock |
| title | Field, Laboratory and Modeling Evidence for Strong Attenuation of a Cr(VI) Plume in a Mudstone Aquifer Due to Matrix Diffusion and Reaction Processes |
| title_full | Field, Laboratory and Modeling Evidence for Strong Attenuation of a Cr(VI) Plume in a Mudstone Aquifer Due to Matrix Diffusion and Reaction Processes |
| title_fullStr | Field, Laboratory and Modeling Evidence for Strong Attenuation of a Cr(VI) Plume in a Mudstone Aquifer Due to Matrix Diffusion and Reaction Processes |
| title_full_unstemmed | Field, Laboratory and Modeling Evidence for Strong Attenuation of a Cr(VI) Plume in a Mudstone Aquifer Due to Matrix Diffusion and Reaction Processes |
| title_short | Field, Laboratory and Modeling Evidence for Strong Attenuation of a Cr(VI) Plume in a Mudstone Aquifer Due to Matrix Diffusion and Reaction Processes |
| title_sort | field laboratory and modeling evidence for strong attenuation of a cr vi plume in a mudstone aquifer due to matrix diffusion and reaction processes |
| topic | hexavalent chromium groundwater plume matrix diffusion reaction attenuation sedimentary bedrock |
| url | https://www.mdpi.com/2571-8789/5/1/18 |
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