J. Horst, C. Divine, J. Tilton, Shandra D. Justicia-Leon, S. Ulrich, R. Stuetzle
{"title":"New Tools for Assessing Reactive Mineral‐Mediated Abiotic Contaminant Transformation","authors":"J. Horst, C. Divine, J. Tilton, Shandra D. Justicia-Leon, S. Ulrich, R. Stuetzle","doi":"10.1111/gwmr.12326","DOIUrl":"https://doi.org/10.1111/gwmr.12326","url":null,"abstract":"This column reviews the general features of PHT3D Version 2, a reactive multicomponent transport model that couples the geochemical modeling software PHREEQC-2 (Parkhurst and Appelo 1999) with three-dimensional groundwater flow and transport simulators MODFLOW2000 and MT3DMS (Zheng and Wang 1999). The original version of PHT3D was developed by Henning Prommer and Version 2 by Henning Prommer and Vincent Post (Prommer and Post 2010). More detailed information about PHT3D is available at the website http://www.pht3d.org. The review was conducted separately by two reviewers. This column is presented in two parts.","PeriodicalId":158105,"journal":{"name":"Groundwater Monitoring & Remediation","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121762958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
John T. Wilson, James C. Mills, B. Wilson, M. Ferrey, D. Freedman, Dora M. Taggart
{"title":"Using qPCR Assays to Predict Rates of Cometabolism of TCE in Aerobic Groundwater","authors":"John T. Wilson, James C. Mills, B. Wilson, M. Ferrey, D. Freedman, Dora M. Taggart","doi":"10.1111/gwmr.12321","DOIUrl":"https://doi.org/10.1111/gwmr.12321","url":null,"abstract":"Monitored natural attenuation (MNA) is commonly used as a remedy for trichloroethene (TCE) in anaerobic groundwater; however, MNA has not been applied to TCE contamination in aerobic groundwater. Under aerobic conditions, bacteria initiate the degradation of many organic substances with oxygenase enzymes. Several of these enzymes are known to degrade TCE through a fortuitous reaction known as cometabolism. There are commercially available qPCR assays that can determine the number of gene copies of these enzymes. If the qPCR assay could be used to predict the first‐order rate constant for cometabolism of TCE, the qPCR assay could be used to screen sites to determine whether MNA was a plausible remedy for TCE contamination. This study reevaluated data from water samples that were collected from 19 wells on five sites in Minnesota, New York, and Utah. Data had previously been published on the rate constant for cometabolism of TCE in the water samples as determined by a 14C‐assay and the abundance of gene copies for five enzymes that cometabolize TCE as determined using a qPCR assay. The Michaelis‐Menten (Haldane) kinetic parameters for cometabolism of TCE and the abundance of DNA for the five oxygenase enzymes were used to predict the rate constant for cometabolism of TCE. The predicted rate constants were evaluated and validated by comparing them to the rate constants derived from the 14C‐assay. For predicted rate constants greater than 0.003 per year, the predicted rate constants agreed with the measured rate constants within a factor of three. The qPCR assay serves as a convenient screening tool to determine whether MNA is a plausible remedy for an aerobic plume of TCE.","PeriodicalId":158105,"journal":{"name":"Groundwater Monitoring & Remediation","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130102779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Approach for Passive Removal of Residual LNAPL from Groundwater","authors":"Kevin D. Svitana, J. South","doi":"10.1111/gwmr.12314","DOIUrl":"https://doi.org/10.1111/gwmr.12314","url":null,"abstract":"Light nonaqueous phase liquids (LNAPLs) are a problematic challenge for obtaining site closure or no further action remediation sites. The source of the LNAPLs varies from leaking underground petroleum storage tanks, to manufacturing facilities where oil leaks create LNAPL accumulations beneath factory floors. Active recovery using pumping or periodic vacuum recovery from wells or sumps is used for remediation, but usually has disappointing results when LNAPL reaccumulates to thicknesses exceeding the 0.01‐foot action level recognized by many states. This paper presents a simple passive approach for recovering persistent LNAPL using nonwoven hydrophobic oil absorbing cloth. The method used laboratory trials to assess physical properties of the cloth. Parameters observed and assessed included sorptive capacity and rate, buoyancy, and LNAPL wicking. It was determined that the cloth could be rolled and secured with cable ties for placement in the wells/sumps. Two placement designs were developed, one where rolled sorbent freely floated on the well/sump fluid surface and a second where the sorbent roll was placed in the fluid column at a fixed depth. Sorbents were then used at two manufacturing facilities where LNAPLs persisted for decades. In both instances, many wells/sumps were reduced to thicknesses below the action level in less than 2 months. In most wells, LNAPL did not reaccumulate. Where it did reaccumulate, it was less than 50% of the original thickness. Using laboratory‐derived recovery rates, cloth sorbents could be sized to minimize placement/recovery frequency while effectively recovering LNAPL.","PeriodicalId":158105,"journal":{"name":"Groundwater Monitoring & Remediation","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121493571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mayra Sarria, J. Gonzales, Daniel Gerrity, J. Batista
{"title":"Biological Reduction of Nitrate and Perchlorate in Soil Microcosms: An Electron Donor Comparison of Glycerol, Emulsified Oil, and Mulch Extract","authors":"Mayra Sarria, J. Gonzales, Daniel Gerrity, J. Batista","doi":"10.1111/gwmr.12315","DOIUrl":"https://doi.org/10.1111/gwmr.12315","url":null,"abstract":"Diverse technologies have been developed and tested for their efficacy in remediating perchlorate‐contaminated surface water, groundwater, and soil. Biological reduction, particularly when coupled with electron donor augmentation, has been shown to be one of the most cost‐effective alternatives. Numerous electron donors have been evaluated in the literature, but few studies have compared standard vs. slow‐release electron donors for sequential nitrate and perchlorate reduction. This study evaluated the efficacy and kinetics of biological reduction in soil microcosms augmented with emulsified oil (EO), glycerol, and mulch extract. Results indicated that EO and glycerol spiked at approximately 100 times stoichiometric excess (i.e., 100x) achieved similar overall reductions and degradation rates for nitrate and perchlorate, although nitrate appeared to exhibit zero order kinetics while perchlorate exhibited first order kinetics. The zero order rate constants for nitrate reduction were 3.32 mg/L d and 2.57 mg/L d for EO and glycerol, respectively. The first order rate constant for perchlorate reduction was 0.36 day−1 for both EO and glycerol. Stable chemical oxygen demand (COD) concentrations also highlighted the slow‐release properties of EO, which would reduce electron donor consumption in comparison to soluble substrates in soil remediation applications. The microcosms augmented with mulch extract failed to demonstrate any nitrate or perchlorate reduction due to the extract's lower COD concentration. Augmentation with compost or additional processing (i.e., concentration) would be necessary to make the extract a viable alternative.","PeriodicalId":158105,"journal":{"name":"Groundwater Monitoring & Remediation","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125385371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Spalding, A. Hirsh, M. Exner, Marty Stange, R. Aravena
{"title":"Integrated Deep Soil N and Groundwater Isotope Investigation of N Sources Captured by Municipal Wells","authors":"R. Spalding, A. Hirsh, M. Exner, Marty Stange, R. Aravena","doi":"10.1111/gwmr.12311","DOIUrl":"https://doi.org/10.1111/gwmr.12311","url":null,"abstract":"Identification of major nitrate sources that adversely impact groundwater quality in municipal well capture zones in areas of emerging nitrate contamination is essential to minimize leaching and prevent exceedance of the nitrate drinking water standard. Vertical profiles of nitrate leachate in deep soils provide an estimate of the amount of nitrate in transit beneath irrigated, row‐cropped fields; depths of peak leachate; and the approximate rate of downward movement. Profiles of pore‐water soil‐nitrate concentrations in thick 60‐feet (~18 m), fine‐textured soils near Hastings, Nebraska clearly indicate that considerably more nitrate leached beneath furrow‐irrigated than center‐pivot irrigated fields. Peak leaching appeared to correlate with recorded periods of poor weather conditions during some growing seasons and may best be controlled by “spoon feeding” fertilizer to the crop through the sprinkler irrigation system at times of nutrient need. The presence of trace levels of atrazine and deethylatrazine to 60 feet (18 m) in core samples indicates that larger, more complex anthropogenic molecules also leach through the fine‐textured soils. The light δ15NNO3 values in the surficial groundwater beneath fertilized and irrigated cropland indicate that ammonium fertilizer is a major N source and suggest that the natural soil‐N contribution is negligible. δ15NNO3 values were most enriched in irrigation wells located within municipal well capture zones downgradient of a large feedlot. Dual isotope method (DIM) δ15NNO3 and δ18ONO3 values suggest that the Hastings’ municipal wells farther downgradient are contaminated with a mixture of nitrate from manure and commercial ammonium‐based fertilizer. DIM values indicate an absence of denitrification, which has implications for long‐term management of the water resources.","PeriodicalId":158105,"journal":{"name":"Groundwater Monitoring & Remediation","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128084685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Felipe M. Solano, M. Marchesi, N. Thomson, D. Bouchard, R. Aravena
{"title":"Carbon and Hydrogen Isotope Fractionation of Benzene, Toluene, and o‐Xylene during Chemical Oxidation by Persulfate","authors":"Felipe M. Solano, M. Marchesi, N. Thomson, D. Bouchard, R. Aravena","doi":"10.1111/gwmr.12228","DOIUrl":"https://doi.org/10.1111/gwmr.12228","url":null,"abstract":"Experiments were performed to investigate the carbon and hydrogen isotope fractionation of benzene, toluene, and o‐xylene (BTX) during chemical oxidation by unactivated persulfate at two concentrations (8 and 20 g/L). Carbon enrichment (ϵC) values of −1.7 ± 0.1‰ for benzene, −0.64 ± 0.1‰ for toluene and −0.36 ± 0.04‰ for o‐xylene were obtained. No significant hydrogen enrichment (ϵH) was observed for benzene, while the hydrogen enrichment for toluene and o‐xylene were −20 ± 3‰ and −23 ± 2‰, respectively. The dual isotope plot (Δδ13C vs. Δδ2H) for benzene and o‐xylene revealed a distinct fractionation trend compared to the majority of the biodegradation data compiled from the literature; however, no unique trend was observed for toluene. The significant carbon and/or hydrogen enrichment, and the distinct trend observed on the dual isotope plot suggest that compound specific isotope analysis (CSIA) can potentially be used to monitor the chemical oxidation of BTX by persulfate, and to distinguish treatment areas where persulfate or biodegradation reactions are occurring for benzene and o‐xylene.","PeriodicalId":158105,"journal":{"name":"Groundwater Monitoring & Remediation","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116553227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mahsa Shayan, N. Thomson, R. Aravena, J. Barker, E. Madsen, M. Marchesi, C. DeRito, D. Bouchard, T. Buscheck, R. Kolhatkar, E. Daniels
{"title":"Integrated Plume Treatment Using Persulfate Coupled with Microbial Sulfate Reduction","authors":"Mahsa Shayan, N. Thomson, R. Aravena, J. Barker, E. Madsen, M. Marchesi, C. DeRito, D. Bouchard, T. Buscheck, R. Kolhatkar, E. Daniels","doi":"10.1111/gwmr.12227","DOIUrl":"https://doi.org/10.1111/gwmr.12227","url":null,"abstract":"The integration or sequential use of different remediation technologies, also referred to as a combined remedy, has become an emerging strategy for the treatment of contaminated sites. Coupling chemical oxidation using persulfate with enhanced bioremediation (EBR) under sulfate reducing conditions is a plausible combined remedy. To characterize the role of the mass removal processes (e.g., chemical oxidation vs. sulfate reduction) and to quantify the impact of persulfate on indigenous microbial processes in a combined persulfate/EBR treatment system, a pilot‐scale field experiment was conducted in a 24‐m long sheet pile‐walled gate over a period of approximately 400 d. After dissolved benzene, toluene, and o‐xylene (BTX) quasi steady‐state plumes were developed, two persulfate injection episodes were performed 10 d apart to create a chemical oxidation (ChemOx) zone. High‐resolution monitoring was conducted to observe the migration of the ChemOx zone and transition into an EBR zone. Mass loss estimates and geochemical indicators were used to identify the distinct transition between the ChemOx and enhanced biological reactive zones. Compound specific isotope analysis (CSIA) was used to distinguish the dominant mass removal process, and to investigate the occurrence of microbial sulfate reduction. BTX metabolites and reverse‐transcriptase quantitative polymerase chain reaction analyses of expressed biodegradation genes (as mRNA) were also used to characterize the response of indigenous microorganisms (especially sulfate‐reducing bacteria) to the added persulfate. Multiple lines of evidence supported the conclusion that chemical oxidation was the dominant mass removal process in the vicinity of the injection zone, while enhanced biodegradation dominated BTX degradation in the downgradient portions of the system. The CSIA and supporting molecular biological data were critical in documenting temporally and spatially distinctive zones in this system that were dominated by either chemical‐oxidation or anaerobic‐biodegradation processes. Initially, persulfate had an inhibitory impact on the activity of the indigenous microbial community, but this was followed by a substantial rebound of microbial activity to above baseline levels. The results from this investigation demonstrate that the suite of diagnostic tools employed can be used to distinguish between chemical oxidation using persulfate and the subsequent effects of the produced sulfate.","PeriodicalId":158105,"journal":{"name":"Groundwater Monitoring & Remediation","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133720521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Special Issue: Diagnostic Tools to Assess In Situ Remediation System Performance","authors":"D. Hunkeler, T. Buscheck","doi":"10.1111/GWMR.12303","DOIUrl":"https://doi.org/10.1111/GWMR.12303","url":null,"abstract":"","PeriodicalId":158105,"journal":{"name":"Groundwater Monitoring & Remediation","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121608279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}