A5068682577- Marine and coastal ecosystems
- Advanced oxidation water treatment
- Atmospheric chemistry and aerosols
- Per- and polyfluoroalkyl substances research
- Pharmaceutical and Antibiotic Environmental Impacts
- Water Quality Monitoring and Analysis
- Water Treatment and Disinfection
- Toxic Organic Pollutants Impact
- Isotope Analysis in Ecology
- Mercury impact and mitigation studies
- Geochemistry and Elemental Analysis
- Pesticide and Herbicide Environmental Studies
- Soil and Water Nutrient Dynamics
- Radioactive element chemistry and processing
- Air Quality and Health Impacts
- Microbial Community Ecology and Physiology
- Environmental Toxicology and Ecotoxicology
- Atmospheric and Environmental Gas Dynamics
- Environmental remediation with nanomaterials
- Water Quality and Resources Studies
- Urban Stormwater Management Solutions
- Analytical chemistry methods development
- Wastewater Treatment and Nitrogen Removal
- Insect and Pesticide Research
- Aquatic Ecosystems and Phytoplankton Dynamics
University of Wisconsin–Madison
2015-2024
Montana State University
2020
Wentworth Institute of Technology
2020
Kettering University
2020
University of Denver
2020
University of Colorado Denver
2020
Bridge University
2020
Madison Group (United States)
2016-2019
ETH Zurich
2011-2012
University of California, Berkeley
2011
The photolysis of hypochlorous acid (HOCl) and hypochlorite (OCl<sup>−</sup>) produces a suite reactive oxidants, including hydroxyl radicals (˙OH), chlorine (Cl˙), ozone (O<sub>3</sub>).
The photochemical production of reactive species, such as triplet dissolved organic matter (3DOM) and singlet oxygen (1O2), contributes to the degradation aquatic contaminants is related an array DOM structural characteristics, notably molecular weight. In order relate weight, optical properties, species production, Suwannee River (SRFA) Pony Lake fulvic acid (PLFA) isolates are fractionated by sequential ultrafiltration, resultant fractions evaluated in terms composition reactivity....
Chlorine photolysis is an advanced oxidation process which relies on photolytic cleavage of free available chlorine (i.e., hypochlorous acid and hypochlorite) to generate hydroxyl radical, along with ozone a suite halogen radicals. Little known about the impact wavelength reactive oxidant generation even though absorbs light within solar spectrum. This study investigates formation oxidants during as function pH (6-10) irradiation (254, 311, 365 nm) using combination quantification validated...
Dissolved organic matter (DOM) composition influences its ability to form photochemically produced reactive intermediates (PPRI). While relationships have been established between bulk DOM properties and triplet (3DOM) singlet oxygen (1O2) quantum yields, contradictory evidence exists for hydroxyl radical (•OH) hydroxylating species. Furthermore, little is known about these at the molecular level. We evaluated photochemical reactivity of water samples from a wastewater treatment plant St....
Abstract High‐resolution mass spectrometry (HRMS) has become a vital tool for dissolved organic matter (DOM) characterization. The upward trend in HRMS analysis of DOM presents challenges data comparison and interpretation among laboratories operating instruments with differing performance user conditions. It is therefore essential that the community establishes metric ranges compositional trends reference samples so can be robustly compared research groups. To this end, four identically...
Predicting the formation of photochemically produced reactive intermediates (PPRI) during irradiation dissolved organic matter (DOM) has remained challenging given complex nature this material and differences in PPRI mechanisms. We investigate role DOM composition photoreactivity using 48 samples that span range freshwater systems wastewater. relate quantum yields for excited triplet-state (fTMP), singlet oxygen (Φ1O2), hydroxylating species (Φ•OH) to determined spectroscopy,...
The North Temperate Lakes Long-Term Ecological Research site includes seven lakes in northern Wisconsin that vary hydrology, trophic status, and landscape position. We examine the molecular composition of dissolved organic matter (DOM) within these using Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) quantify DOM photochemical activity probe compounds. Correlations between relative intensity individual formulas reactive species production demonstrate influence on...
The addition of photosensitizers to water can accelerate disinfection in sunlight-based systems by enhancing oxidation target compounds through direct reaction with the excited sensitizer or production another oxidant, such as singlet oxygen (1O2). kinetics selected amino acids presence riboflavin (Vitamin B2), its primary photoproduct lumichrome, and derivative tetraacetate (2′,3′,4′,5′-tetraacetylriboflavin; RTA) were quantified mechanisms determined during exposure 365 ± 9 nm light....
Ozonation of drinking and wastewater relies on ozone (O3) hydroxyl radical (•OH) as oxidants. Both oxidants react with dissolved organic matter (DOM) alter its composition, but the selectivity two mechanisms reactivity DOM moieties are largely unknown. The reactions O3 •OH isolates were studied by varying specific doses (0.1–1.3 mg-O3/mg-C) at pH 7. Additionally, conditions that favor (i.e., addition an scavenger) or 11) investigated. decreases aromaticity, apparent molecular weight,...
Bisphenol A (BPA) is an endocrine-disrupting compound widely used in the plastic industry and found natural waters at concentrations considered harmful for aquatic life. BPA susceptible to oxidation by Mn(III/IV) oxides, which are commonly near-surface environments. Here, we quantify rates formation of its predominant product, 4-hydroxycumyl alcohol (HCA), tandem with transformation a synthetic, Mn(III)-rich δ-MnO2. To investigate effect Mn oxide structural changes on rate, 12 sequential...
The multiple reactive oxidants produced during chlorine photolysis effectively degrade organic contaminants water treatment, but their role in disinfection byproduct (DBP) formation is unclear. impact of on dissolved matter (DOM) composition and DBP investigated using lake collected after coagulation, flocculation, filtration at pH 6.5 8.5 with irradiation three wavelengths (254, 311, 365 nm). steady-state concentrations hydroxyl radical decrease by 38–100% drinking compared to ultrapure...
Dissolved organic matter (DOM) varies widely across natural and engineered systems, but little is known about the influence of DOM composition on its reactivity with manganese oxides. Here, we investigate bulk molecular transformations 30 diverse samples after reaction acid birnessite (MnO2), a strong oxidant that may react in Mn-rich environments or treatment systems. The reduces Mn forms generally more aliphatic lower apparent weight. However, extent depends water type (e.g., wastewater,...
Transport of per- and polyfluoroalkyl substances (PFAS) to the Great Lakes is great importance as this large freshwater system provides drinking water over 40 million people. Tributary PFAS loading poorly characterized, role sediments a source or sink largely unknown. We quantified 10 perfluoroalkyl acids (PFAAs) in (4–1310 ng/L) sediment (below detection 3255 ng/kg) 41 tributaries Green Bay Lake Michigan. demonstrate that tributary discharge plays major contribution receiving waters. In...
Dissolved organic matter (DOM) plays an important role in carbon cycling within inland surface waters. Under sunlight irradiation, DOM undergoes complete photooxidation to produce dioxide (CO2) and partial that alters the molecular composition of DOM. However, a mechanistic understanding relationship between its susceptibility waters is currently lacking. This work combines light exposure experiments with high-resolution mass spectrometry investigate using two isolates from 16 lakes vary...
Suwannee River fulvic acid (SRFA) was dialyzed through a 100–500 molecular weight cutoff dialysis membrane, and the dialysate retentate were analyzed by UV–visible absorption high-resolution Orbitrap mass spectrometry (MS). A significant fraction (36% based on dissolved organic carbon) of SRFA passed membrane. The in had different spectrum enriched low molecules with more aliphatic composition relative to initial solution. Comparison spectra collected MS Fourier transform ion cyclotron...
This research investigated chlorinated byproduct formation at Ti4O7 anodes. Resorcinol was used as a model organic compound representative of reactive phenolic groups in natural matter and industrial contaminants oxidized the presence NaCl (0—5 mM). mineralization >68% absence 3.1 V/SHE (residence time = 13 s). Results indicated that ∼4.3% initial chloride converted to inorganic byproducts (free Cl2, ClO2–, ClO3–) resorcinol, this value decreased <0.8% resorcinol. Perchlorate rates from...
In this study, complementary techniques, including ultrahigh-resolution Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) and X-ray photoelectron spectroscopy (XPS), were applied to characterize the transformation of nitrogen components during hydrothermal liquefaction (HTL) sewage sludge. Results showed that 3–35% in sludge was transferred into biocrude product when using HTL reaction temperatures ranging from 200 350 °C, with remaining partitioning aqueous, solid,...
Abstract Many challenges remain before we can fully understand the multifaceted role that natural organic matter (NOM) plays in soil and aquatic systems. These despite considerable progress has been made understanding NOM’s properties reactivity using latest analytical techniques. For nearly 4 decades, International Humic Substances Society (IHSS, which is a non-profit scientific society) distributed standard substances adhere to strict isolation protocols reference materials are collected...
Per- and polyfluoroalkyl substances (PFAS) are surfactants that can accumulate in the surface microlayer (SML) natural foams, with potential elevated exposure for organisms at water surface. However, impact of chemistry on PFAS accumulation these matrices freshwater systems is unknown. We quantified 36 water, SML, foams from 43 rivers lakes Wisconsin, USA, alongside measurements pH, cations, dissolved organic carbon (DOC). partition to concentration ranging 2300–328,200 ng/L waters 6–139...
Abstract Dissolved organic matter (DOM) is a fundamental driver of many lake processes. In the past several decades, lakes have exhibited substantial increase in DOM quantity, measured as dissolved carbon (DOC) concentration. While increasing DOC now widely recognized, fewer studies sought to understand how characteristics (DOM quality ) change over time. Quality can be ways, including optical spectral slope ( S 275–295 ), ratio R absorbance at 254 nm A and DOC‐specific (SUVA; :DOC)....