A5011357018- Groundwater flow and contamination studies
- Toxic Organic Pollutants Impact
- Radioactive element chemistry and processing
- Soil and Water Nutrient Dynamics
- Hydrology and Watershed Management Studies
- Water Treatment and Disinfection
- Groundwater and Isotope Geochemistry
- Soil and Unsaturated Flow
- Atmospheric chemistry and aerosols
- Environmental remediation with nanomaterials
- Atmospheric and Environmental Gas Dynamics
- Water Quality and Resources Studies
- Nanopore and Nanochannel Transport Studies
- Water Quality Monitoring and Analysis
- Marine and coastal ecosystems
- Fish Ecology and Management Studies
- Radioactive contamination and transfer
- Catalytic Processes in Materials Science
- Zeolite Catalysis and Synthesis
- Hydraulic Fracturing and Reservoir Analysis
- Microbial bioremediation and biosurfactants
- CO2 Sequestration and Geologic Interactions
- Hydrocarbon exploration and reservoir analysis
- NMR spectroscopy and applications
- Urban Stormwater Management Solutions
Johns Hopkins University
2010-2021
Chesapeake Research Consortium
2016-2021
Stanford University
1986-2013
Pacific Northwest National Laboratory
2005-2009
Notre Dame of Maryland University
2008
University of Maryland Center for Environmental Science
2008
University of Delaware
2008
DuPont (United States)
2008
Hampton University
2008
National Institute of Standards and Technology
2007
Black carbon (BC), the product of incomplete combustion fossil fuels and biomass (called elemental (EC) in atmospheric sciences), was quantified 12 different materials by 17 laboratories from disciplines, using seven methods. The were divided into three classes: (1) potentially interfering materials, (2) laboratory‐produced BC‐rich (3) BC‐containing environmental matrices (from soil, water, sediment, atmosphere). This is first comprehensive intercomparison this type (multimethod, multilab,...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLong-term sorption of halogenated organic chemicals by aquifer material. 2. Intraparticle diffusionWilliam P. Ball and Paul V. RobertsCite this: Environ. Sci. Technol. 1991, 25, 7, 1237–1249Publication Date (Print):July 1, 1991Publication History Published online1 May 2002Published inissue 1 July 1991https://pubs.acs.org/doi/10.1021/es00019a003https://doi.org/10.1021/es00019a003research-articleACS PublicationsRequest reuse permissionsArticle...
As greater quantities of carbon nanotubes (CNTs) enter the environment, they will have an increasingly important effect on availability and transport aqueous contaminants. a consequence purification, deliberate surface functionalization, and/or exposure to oxidizing agents after release CNTs often contain oxides (i.e., oxygen containing functional groups). To probe influence that exert CNT sorption properties, multiwalled (MWCNTs) with varying concentrations were studied respect their...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLong-term sorption of halogenated organic chemicals by aquifer material. 1. EquilibriumWilliam P. Ball and Paul V. RobertsCite this: Environ. Sci. Technol. 1991, 25, 7, 1223–1237Publication Date (Print):July 1, 1991Publication History Published online1 May 2002Published inissue 1 July 1991https://pubs.acs.org/doi/10.1021/es00019a002https://doi.org/10.1021/es00019a002research-articleACS PublicationsRequest reuse permissionsArticle...
Values of the organic-carbon-based partition coefficient (Koc) have often been estimated using one-parameter linear free energy relationships (op-LFERs), which include both correlations between log Koc and Kow, where Kow is octanol−water coefficient, op-LFERs that are based on first-order molecular connectivity indices. For chemicals with tendencies toward strong hydrogen-bonding or other specific interactions organic phase, however, these methods not sufficiently accurate. Polyparameter...
Sorption of comparatively nonpolar organic chemicals by natural solids not only can be predominated partitioning with matter but also reflect a substantial contribution from adsorption at low relative concentration. nine polycyclic aromatic hydrocarbons (PAHs) and chlorinated benzenes (CBs) was investigated on subsurface aquitard through batch study, results interpreted composite adsorption-partitioning model. For both PAHs CBs, the low-concentration slope coefficient for each correlated...
Studies were conducted to examine the effect of solution chemistry, defined here as pH and ionic strength, on permeability negatively charged polymeric nanofiltration membranes. Water permeation through membrane was demonstrated decrease at conditions low high strength in absence organic macromolecules. The reduction attributed a compaction matrix resulting from charge neutralization surface electric double layer compression. An uncharged model macromolecule (polyethylene glycol) used...
Exposure of multiwalled carbon nanotubes (MWCNTs) to oxidizing acids and other oxidants introduces oxygen-containing functional groups such as hydroxyl, carboxyl, carbonyl onto the surface. This research evaluated how changes in oxygen concentration distribution influenced sorption aqueous zinc cadmium on MWCNTs. Sorption results with natural char, activated carbon, a suite MWCNTs (of varying surface content) were obtained. Results confirmed that enhances both Zn[II] Cd[II] from solution....
Sorption isotherms for five aromatic hydrocarbons were obtained with a natural wood char (NC1) and its residue after solvent extraction (ENC1). Substantial isotherm nonlinearity was observed in all cases. ENC1 showed higher BET surface area, nitrogen-accessible micropore volume, lower mass of extractable organic chemicals, including quantifiable polycyclic (PAHs), while the two chars identical oxygen/carbon (O/C) ratio. For chlorinated benzenes that normally condense as liquids at...
Although granular iron permeable reactive barriers (PRBs) are increasingly employed to contain subsurface contaminants, information pertaining system longevity is sparse. The present investigation redresses this situation by examining the long-term effects of carbonate, silica, chloride, and natural organic matter (NOM) on reactivity Master Builders toward organohalides nitroaromatic contaminants. Six columns were operated for 1100 days (approximately 4500 pore volumes) five others 407 1800...
Grafting oxygen-containing functional groups onto carbon nanotubes (CNTs) by acid treatment improves their dispersion in aqueous solutions, but there is a lack of quantitative information on the colloidal properties oxidized CNTs. We have studied influence that pH and electrolytes determining stability multiwalled (O-MWCNTs), prepared refluxing pristine MWCNTs nitric acid. The acid-treated contained oxygen predominantly form carboxyl groups. Colloidal suspensions O-MWCNTs were low-power...
As with all nanomaterials, a large fraction of the atoms in carbon nanotubes (CNTs) reside at or near surface. Consequently, surface chemistry will play crucial role determining fate and transport CNTs aquatic environments. Frequently, oxygen-containing functional groups (surface oxides) are deliberately grafted into CNT to promote colloidal stability. To study influence that both oxygen concentration functional-group distribution have on stability multiwalled (MWCNTs), suite oxidized MWCNTs...
Environmental context. The fate and bioavailability of engineered nanoparticles in natural aquatic systems are strongly influenced by their ability to remain dispersed water. Consequently, understanding the colloidal properties through rigorous characterisation physicochemical measurements particle stability will allow for a more accurate prediction environmental, health, safety effects systems. This review highlights some important techniques suitable assessment discusses recent findings...
Turbidity is an internationally recognized criterion for assessing drinking water quality, because the colloidal particles in turbid may harbor pathogens, chemically reduce oxidizing disinfectants, and hinder attempts to disinfect with ultraviolet radiation. A turbidimeter electronic/optical instrument that assesses turbidity by measuring scattering of light passing through a sample containing such particles. Commercial turbidimeters cost hundreds or thousands dollars, putting them beyond...
Abstract Hydrologists have a relatively good understanding of how rainfall variability shapes the catchment hydrograph, reflection celerity hydraulic head propagation. Much less is known about influence on transit times, water velocities that control solute transport. This work uses catchment‐scale lumped parameter models to decompose relationship between and an important metric time‐varying fraction young (<90 days old) in streams (FYW). A coupled rainfall‐runoff model rank StorAge...
The influence of calcite and dissolved calcium on U(VI) adsorption was investigated using a calcite-containing sandy silt/clay sediment from the U. S. Department Energy Hanford site. to sediment, treated size fractions studied in solutions that both had not been preequilibrated with calcite, at initial [U(VI)] = 10-7−10-5 mol/L final pH 6.0−10.0. Kinetic reversibility studies (pH 8.4) showed rapid sorption (30 min), reasonable 3-day reaction time. Sorption equilibrated maximum 8.4 ± 0.1. In...
Abstract Vertical profiles of tetrachloroethene (or perchloroethylene, PCE) and trichloroethene (TCE) were used to validate a diffusion process in natural aquitard at Dover Air Force Base, Delaware. PCE TCE distributions the underlying an unconfined aquifer sampled from core tubes obtained four times over course 35–month field investigation within “test cells” that isolated surrounding ground water by means grout‐sealed steel sheetpile barriers (Mackay et al. 2000). For final 23 months this...
Spatial interpolation methods are frequently used to estimate values of physical or chemical constituents in locations where they not measured. Very little research has been conducted, however, investigate the relative performance different surface waters. The study reported here uses archived water quality data from Chesapeake Bay compare three spatial methods: inverse distance weighting, ordinary kriging, and a universal kriging method that incorporates output process-based model....