A5088260320- Groundwater flow and contamination studies
- Water Quality and Resources Studies
- Microbial bioremediation and biosurfactants
- Groundwater and Isotope Geochemistry
- Water Treatment and Disinfection
- Atmospheric and Environmental Gas Dynamics
- Toxic Organic Pollutants Impact
- Water Quality Monitoring and Analysis
- Methane Hydrates and Related Phenomena
- Wastewater Treatment and Nitrogen Removal
- Per- and polyfluoroalkyl substances research
- Chemical Analysis and Environmental Impact
- Soil and Water Nutrient Dynamics
- CO2 Sequestration and Geologic Interactions
- Chemical Reactions and Isotopes
- Geophysical Methods and Applications
- Microbial Community Ecology and Physiology
- Constructed Wetlands for Wastewater Treatment
- Environmental remediation with nanomaterials
- Oil Spill Detection and Mitigation
- Electrochemical Analysis and Applications
- Anaerobic Digestion and Biogas Production
- Karst Systems and Hydrogeology
- Mine drainage and remediation techniques
- Effects and risks of endocrine disrupting chemicals
District of Columbia Water and Sewer Authority
2015-2024
United States Geological Survey
2011-2024
Maryland-Delaware-D.C. Water Science Center
2015-2024
United States Department of the Interior
2002-2014
CECOM Software Engineering Center
2002
Pennsylvania State University
1991
University of Virginia
1987-1988
Leachate from municipal landfills can create groundwater contaminant plumes that may last for decades to centuries. The fate of reactive contaminants in leachate-affected aquifers depends on the sustainability biogeochemical processes affecting transport. Temporal variations configuration redox zones downgradient Norman Landfill were studied more than a decade. leachate plume contained elevated concentrations nonvolatile dissolved organic carbon (NVDOC) (up 300 mg/L), methane (16 ammonium...
Drinking water supplies across the United States have been contaminated by firefighting and fire-training activities that use aqueous film-forming foams (AFFF) containing per- polyfluoroalkyl substances (PFAS). Much of AFFF is manufactured using electrochemical fluorination 3M. Precursors with six perfluorinated carbons (C6) non-fluorinated amine substituents make up approximately one-third PFAS in 3M AFFF. C6 precursors can be transformed through nitrification (microbial oxidation) moieties...
Perfluorooctane sulfonate (PFOS), one of the most frequently detected per- and polyfluoroalkyl substances (PFAS) occurring in soil, surface water, groundwater near sites contaminated with aqueous film-forming foam (AFFF), has proven to be recalcitrant many destructive remedies, including chemical oxidation. We investigated potential utilize microbially mediated reduction (bioreduction) degrade PFOS other PFAS through addition a known dehalogenating culture, WBC-2, soil obtained from an...
This field study focuses on quantitatively defining the chemical changes occurring in Falling Spring Creek, a travertine‐depositing stream located Alleghany County, Virginia. The processes of CO 2 outgassing and calcite precipitation or dissolution control evolution stream. observed composition water was used with computerized geochemical model WATEQF to calculate aqueous speciation, saturation indices, partial pressure values. Mass balance calculations were performed obtain mass transfers...
Field evidence collected along two groundwater flow paths shows that anaerobic biodegradation naturally attenuates a plume of chlorinated volatile organic compounds as it discharges from an aerobic sand aquifer through wetland sediments. A decrease in concentrations parent contaminants, trichloroethylene (TCE) and 1,1,2,2‐tetrachloroethane (PCA), concomitant increase daughter products occurs upward the The 1,2‐dichloroethylene, vinyl chloride, 1,1,2‐trichloroethane, 1,2‐dichloroethane are...
Degradation reactions controlling the fate of 1,1,2,2-tetrachloroethane (PCA) in a freshwater tidal wetland that is discharge area for contaminated aquifer were investigated by combined field and laboratory study. Samples from nested piezometers porous-membrane sampling devices (peepers) showed PCA concentrations decreased less chlorinated daughter products formed as groundwater became increasingly reducing along upward flow paths through sediments. The cis trans isomers 1,2-dichloroethylene...
ABSTRACT Mixed cultures capable of dechlorinating chlorinated ethanes and ethenes were enriched from contaminated wetland sediment at Aberdeen Proving Ground (APG) Maryland. The "West Branch Consortium" (WBC-2) was degrading 1,1,2,2-tetrachloroethane (TeCA), trichloroethene (TCE), cis trans 1,2-dichloroethene (DCE), 1,1,2-trichloroethane (TCA), 1,2-dichloroethane, vinyl chloride to nonchlorinated end products ethene ethane. WBC-2 dechlorinated TeCA, TCA, cisDCE rapidly simultaneously. A...
Abstract Forty passive vapor samplers were placed in creek‐bottom sediment an area where ground water contaminated with volatile organic compounds is discharging to surface water. The composed of activated carbon fused a ferromagnetic wire test tube. analyzed laboratory using extranuclear quadrupole mass spectrometer. Data from the reveal distributions chloroform, tetrachloroethylene, trichloroethylene, and benzene bottom that closely correspond distribution those adjacent Moreover,...
Bioaugmentation is a promising strategy for enhancing trichloroethylene (TCE) degradation in fractured rock. However, slow or incomplete biodegradation can lead to stalling at byproducts such as 1,2-dichloroethene (cis-DCE) and vinyl chloride (VC). Over the course of 7 years, we examined response groundwater microbial populations bioaugmentation test where an emulsified vegetable oil solution (EOS®) dechlorinating consortium (KB-1®), containing established dechlorinator Dehalococcoides...
Chlorinated solvents, including 1,1,2,2-tetrachloroethane, tetrachloroethene, trichloroethene, carbon tetrachloride, and chloroform, are reaching land surface in localized areas of focused ground-water discharge (seeps) a wetland tidal creek the West Branch Canal Creek area, Aberdeen Proving Ground, Maryland. In cooperation with U.S. Army Garrison, Maryland, Geological Survey is developing enhanced bioremediation methods that simulate natural anaerobic degradation occurs without intervention...
The wide range of redox conditions and diversity microbial populations in organic-rich wetland sediments could enhance biodegradation chlorinated solvents. To evaluate potential rates trichloroethylene (TCE) its anaerobic daughter products (cis-1,2-dichloroethylene; trans-1,2-dichloroethylene; vinyl chloride), laboratory microcosms were prepared under methanogenic, sulfate-reducing, aerobic using sediment groundwater from a freshwater that is discharge area for TCE contaminant plume. Under...
Abstract Decomposition of organic‐rich bottom sediment in a tidal creek Maryland results production gas bubbles the during summer and fall. In areas where volatile organic contaminants discharge from ground water, through sediment, into creek, part contamination diffuses is released to atmosphere by ebullition. Collection analysis for their contaminant content indicate that relative concentrations are substantially higher same occur water discharges streams. Analyses located an area...
0-Field, in the Edgewood area of Aberdeen Proving Ground, Maryland, periodically was used for disposal munitions, waste chemicals, and chemical-warfare agents from World War II to at least 1950's.This has resulted contamination ground water, surface bottom sediment site.Contaminated water contains concentrations arsenic cadmium that exceed drinking-water maximum contaminant levels chloride, iron, manganese, zinc secondary established by U.S. Environmental Protection Agency (1987).Dominant...
Wetlands act as natural transition zones between ground water and surface water, characterized by the complex interdependency of hydrology, chemical physical properties, biotic effects. Although field laboratory demonstrations have shown efficient attenuation processes in non-seep wetland areas stream bottom sediments West Branch Canal Creek, chlorinated volatile organic compounds are present a freshwater tidal creek at Aberdeen Proving Ground, Maryland. Volatile compound concentrations...