Sercu B.,University of California at Santa Barbara |
Jones A.D.G.,ENVIRON International Corporation |
Wu C.H.,Lawrence Berkeley National Laboratory |
Escobar M.H.,ENVIRON International Corporation |
And 5 more authors.
Microbial Ecology | Year: 2013
In situ chemical oxidation with permanganate has become an accepted remedial treatment for groundwater contaminated with chlorinated solvents. This study focuses on the immediate and short-term effects of sodium permanganate (NaMnO4) on the indigenous subsurface microbial community composition in groundwater impacted by trichloroethylene (TCE). Planktonic and biofilm microbial communities were studied using groundwater grab samples and reticulated vitreous carbon passive samplers, respectively. Microbial community composition was analyzed by terminal restriction fragment length polymorphism and a high-density phylogenetic microarray (PhyloChip). Significant reductions in microbial diversity and biomass were shown during NaMnO4 exposure, followed by recovery within several weeks after the oxidant concentrations decreased to <1 mg/L. Bray-Curtis similarities and nonmetric multidimensional scaling showed that microbial community composition before and after NaMnO4 was similar, when taking into account the natural variation of the microbial communities. Also, 16S rRNA genes of two reductive dechlorinators (Desulfuromonas spp. and Sulfurospirillum spp.) and diverse taxa capable of cometabolic TCE oxidation were detected in similar quantities by PhyloChip across all monitoring wells, irrespective of NaMnO4 exposure and TCE concentrations. However, minimal biodegradation of TCE was observed in this study, based on oxidized conditions, concentration patterns of chlorinated and nonchlorinated hydrocarbons, geochemistry, and spatiotemporal distribution of TCE-degrading bacteria. © 2012 Springer Science+Business Media, LLC.
Zdon A.,Andy Zdon & Associates Inc. |
Davisson M.L.,ML Davisson & Associates Inc. |
Love A.H.,Roux Associates Inc.
Environmental Forensics | Year: 2015
The current conceptual hydrogeologic model established for source water to the Amargosa River was tested in order to help inform management decisions regarding the Amargosa River's Federal designation as Wild and Scenic through an Act of Congress. The limited availability of water in this region results in the critical need for effective management in the basin to maintain its Wild and Scenic attributes inclusive of habitat for several endangered and threatened species. The use of forensic tools and integration of multiple lines of geologic, hydrogeologic, geochemical, and stable isotopic evidence suggest that the simple historical model for primary groundwater transport through this region is incorrect and that a large supply of regional baseflow does not provide the hydrogeological foundation of the Amargosa River basin. Data collected is consistent with an alternative model requiring complex source mixing and shallow alluvial groundwater that supports river flow. This conclusion also suggests Wild and Scenic conditions in this basin are more precarious than previously understood. © 2015, Copyright © Taylor & Francis Group, LLC.
Cao H.,Louisiana State University |
Cao H.,Roux Associates Inc. |
Tsai F.T.-C.,Louisiana State University |
Rusch K.A.,Louisiana State University
Ground Water | Year: 2010
The objective of this research was to study the sorption and transport of bacteriophage MS-2 (a bacterial virus) in saturated sediments under the effect of salinity and soluble organic matter (SOM). One-dimensional column experiments were conducted on washed high-purity silica sand and sandy soil. In sand column tests, increasing salinity showed distinct effect on enhancing MS-2 sorption. However, SOM decreased MS-2 sorption. Using a two-site reversible-irreversible sorption model and the double layer theory, we explained that pore-water salinity potentially compressed the theoretical thickness of double layers of MS-2 and sand, and thus increased sorption on reversible sorption sites. On irreversible sorption sites, increasing salinity reversed charges of some sand particles from negative to positive, and thus converted reversible sorption sites into irreversible sites and enhanced sorption of MS-2. SOM was able to expand the double layer thickness on reversible sites and competed with MS-2 for the same binding place on irreversible sites. In sandy soil column tests, the bonded and dissolved (natural) soil organic matters suppressed the effects of pore-water salinity and added SOM and significantly reduced MS-2 adsorption. This was explained that the bonded soil organic matter occupied a great portion of sorption sites and significantly reduced sorption sites for MS-2. In addition, the dissolved soil organic matter potentially expanded the double layer thickness of MS-2 and sandy soil on reversible sorption sites and competed with MS-2 for the same binding place. © 2009 National Ground Water Association.
Ram N.M.,Roux Associates Inc. |
Scott J.,Roux Associates Inc. |
Szymaszek K.,Roux Associates Inc. |
Swanson D.,Roux Associates Inc.
Remediation | Year: 2014
Leaking underground storage tank systems at service stations have resulted in tens of thousands of petroleum releases and associated groundwater chemical plumes often extending hundreds of feet off-site. Technical and engineering approaches to assess and clean up releases from underground tanks, product lines, and dispensers using technologies such as soil vapor extraction, air sparging, biostimulation, and monitored natural attenuation are well understood and widely published throughout the literature. This article summarizes life-cycle environmental response costs typically encountered using site-specific cost estimation or metric-based cost categories considering the overall complexity of site conditions: (1) simple sites where response actions require smaller scale assessments and/or remediation and have limited or no off-site impacts; (2) average sites where response actions require larger scale assessments and/or remediation typical of petroleum releases; (3) complex sites where response actions require greater on-site and/or off-site remediation efforts; and (4) mega sites where petroleum plumes have impacted public or private water supplies or where petroleum vapors have migrated into occupied buildings. Associated cleanup cost estimates rely upon appropriate combinations of individual work elements and the duration of operation, maintenance, and monitoring activities. These cost estimates can be offset by state reimbursement funds, coverage in purchase agreements, and insurance policies. A case study involving a large service station site portfolio illustrates the range of site complexity and life-cycle environmental response costs. © 2014 Wiley Periodicals, Inc.
Eisen P.A.,Roux Associates Inc.
Air and Waste Management Association - Climate Change Conference 2013: Impacts, Policy and Regulation | Year: 2014
Sandy was a powerful storm, and the damage it caused was widespread throughout the New York and New Jersey region4. The storm's low central pressure created a large circulation that generated a truly remarkable storm tide. The Hudson River is an estuary from the lower New York City harbor (the Battery) northward past Albany to Troy, NY, 153 miles from the Battery. The storm tide generated by Sandy traveled from the Battery all the way north on the Hudson River to Troy, as the Hurricane made its landfall in southern New Jersey. A storm surge of approximately five feet above predicted tide was observed at a NOAA station in Albany, NY (approximately 135 miles from the station located in the Battery).