A5008766374- Arsenic contamination and mitigation
- Heavy metals in environment
- Environmental remediation with nanomaterials
- Radioactive element chemistry and processing
- Mine drainage and remediation techniques
- Geochemistry and Elemental Analysis
- Iron oxide chemistry and applications
- Constructed Wetlands for Wastewater Treatment
- Adsorption and biosorption for pollutant removal
- HIV Research and Treatment
- Groundwater flow and contamination studies
- Mercury impact and mitigation studies
- Fluoride Effects and Removal
- Phosphorus and nutrient management
- Groundwater and Isotope Geochemistry
- Coal and Its By-products
- Microbial Fuel Cells and Bioremediation
- Extraction and Separation Processes
- Atmospheric and Environmental Gas Dynamics
- Herpesvirus Infections and Treatments
- Monoclonal and Polyclonal Antibodies Research
- Wastewater Treatment and Nitrogen Removal
- Chromium effects and bioremediation
- Water Quality and Pollution Assessment
- Plant nutrient uptake and metabolism
Translational Health Science and Technology Institute
2017-2025
Stanford University
2015-2024
Wageningen University & Research
2022-2024
University of Vienna
2019-2024
Duke University
2017-2024
Kurukshetra University
2020
Lala Lajpat Rai University of Veterinary and Animal Sciences
2020
Stanford Medicine
2018
Centre de Recherche et d’Enseignement de Géosciences de l’Environnement
2013-2017
Centre National de la Recherche Scientifique
2013-2017
Sorption to iron (Fe) minerals determines the fate of toxic metalloid arsenic (As) in many subsurface environments. Recently, thiolated As species have been shown dominate aqueous speciation under a range environmentally relevant conditions, thus highlighting need for quantitative understanding their sorption behavior. We conducted batch experiments measure time-dependent two S-substituted arsenate species, mono- and tetrathioarsenate, compared it arsenite arsenate, suspensions containing...
Oxidation behavior of nano-Fe0 particles in an anoxic environment was determined using different state-of-the-art analytical approaches, including high resolution transmission electron microscopy (HR-TEM) combined with energy filtered (EFTEM), X-ray absorption spectroscopy (XAS), and magnetic measurements. controlled experiments compared standard double distilled (DD) water, DD water spiked trichloroethene (TCE), TCE contaminated site water. Using HR-TEM EFTEM, we observed a surface oxide...
The association of poorly crystalline iron (hydr)oxides with organic matter (OM), such as extracellular polymeric substances (EPS), exerts a profound effect on Fe and C cycles in soils sediments, their behaviors under sulfate-reducing conditions involve complicated mineralogical transformations. However, how different loadings types EPS water chemistry affect the sulfidation still lacks quantitative systematic investigation. We here synthesized set ferrihydrite–organic (Fh–OM) coprecipitates...
We assessed the potential of zerovalent-iron- (Fe(0)) based permeable reactive barrier (PRB) systems for arsenic (As) remediation in presence or absence microbial sulfate reduction. conducted long-term (200 day) flow-through column experiments to investigate mechanisms As transformation and mobility aquifer sediment (in particular, PRB downstream linkage). Changes speciation aqueous phase were monitored continuously. Speciation solid was determined at end experiment using X-ray absorption...
Groundwater contamination by As from natural and anthropogenic sources is a worldwide concern. Redox heterogeneities over space time are common can influence the molecular-level speciation of As, thus, release/retention but largely unexplored. Here, we present results dual-domain column experiment, with organic-rich, fine-grained, sulfidic sediments embedded as lenses (referred to "reducing lenses") within aquifer sand. We show that redox interfaces in sulfur-rich, alkaline aquifers may...
Use of crystal nanocellulose to stabilize nano-ZVI has tremendous potential improve the capability and applicability based subsurface remediation systems in an environmentally sustainable way.
We used synchrotron-based X-ray absorption spectroscopy, transmission electron microscopy, and wet chemical analyses to study the sulfidation mechanism(s) sulfur oxidation products from reaction of ferrihydrite, goethite, hematite nanoparticles with dissolved sulfide at different S/Fe molar ratios under anaerobic condition.
The prevalence of manganese (Mn) in Southeast Asian drinking water has recently become a topic discussion, particularly when concurrent with elevated arsenic (As). Although Mn groundwater geochemistry been studied, the link between dissolved organic matter (DOM) quality and release is less understood. This work evaluates characteristics DOM, redox chemistry, distribution within Murshidabad, West Bengal, India. Shallow aquifer samples were analyzed for cations, anions, carbon, DOM properties...
Peatlands and other wetlands are sinks for antimony (Sb), solid natural organic matter (NOM) may play an important role in controlling Sb binding. However, direct evidence of sequestration peat samples is lacking. Here, we analyzed phase Sb, iron (Fe), sulfur (S) as well aqueous speciation three profiles up to a depth 80 cm mine water impacted peatland northern Finland. Linear combination fittings extended X-ray absorption fine structure spectra showed that binding Fe phases was minor...
Peatlands and other wetlands with abundant natural organic matter (NOM) are important sinks for antimony (Sb). While formation of Sb(III) sulfide phases or binding to NOM discussed decrease Sb mobility, the exact mechanisms remain elusive. Here, we reacted increasing concentrations purified model peat at pH 6, forming reduced sulfur species, subsequently equilibrated reaction products 50 μM antimonite under anoxic conditions. Sulfur solid-phase speciation local environment were analyzed...
Stable mercury (Hg) isotope ratios are an emerging tracer for biogeochemical transformations in environmental systems, but their application requires knowledge of isotopic enrichment factors individual processes. We investigated Hg fractionation during dark, abiotic reduction Hg(II) by dissolved iron(Fe)(II), magnetite, and Fe(II) sorbed to boehmite or goethite analyzing both the reactants products laboratory experiments. For homogeneous continuously purged reactors, results followed a...