Environmental and Analytical Chemistry: Fate and transport of emerging contaminants and endocrine disrupting chemicals; treatment of pharmaceuticals and personal care products in wastewater; bioaccumulation of halogenated organic contaminants in fish and wildlife; target and non-target analysis of environmental contaminants; bioremediation of perfluoroalkyl substances; antibiotic resistance in the environment.
Fate and transport of pollutants (antibiotics, endocrine disrupting chemicals, engineered nanomaterials); environmental chemistry and toxicology, environmental sampling and analysis, wastewater treatment of micropollutants, capillary zone electrophoresis (CZE), liquid chromatography/mass spectrometry (LC/MS), enzyme-linked immunosorbent assay (ELISA), gas chromatography/mass spectrometry (GC/MS), inductively coupled plasma/mass spectrometry (ICP/MS).
Our research involves the development and applications of conventional and innovative analytical techniques to study the environmental fate and transport of emerging contaminants. Some of the questions we intend to answer are: (1) how fast and by what means do these chemicals degrade?, (2) what are the major breakdown products of these compounds in the environment?, (3) how do environmental conditions affect the persistence and mobility of these contaminants? and (4) are these compounds of significant ecotoxicological concern?
Analytical Chemistry plays a key role in our investigations to answer several fundamental questions in environmental chemistry. We use modern instruments such as LC/MS/MS, CZE, ICP/MS and GC/MS/MS, in combination with bioassays as tools to study many important environmental processes. Development of effective sample preparation techniques such as solid-phase extraction (SPE), accelerated solvent extraction (ASE), and solid-phase microextraction (SPME) are critical in obtaining reliable and accurate results.
Non-target Analysis of Emerging Contaminants in the Environment
A rapidly growing approach in environmental analysis and toxicology research involves the use of non-target analysis (NTA) with high resolution mass spectrometry (HRMS), where data on accurate masses of molecular and fragment ions are collected without a priori information on the chemicals being analyzed to increase detection coverage. Our group has been developing efficient NTA workflows for various applications ranging from the discovery of unknown contaminants in the environment to global profiling of metabolite composition (metabolomics) in affected organisms. We have applied NTA in metabolomics studies to facilitate the understanding of the effects of chemical perturbations on exposed organisms, such as plants and animals, without focusing on a particular biochemical pathway. We have combined HRMS with in silico approaches for the identification of PBDE metabolites, previously unidentified antibiotics and transformation products, and unknown Per- and Polyfluoroalkyl substances (PFAS) in biological and environmental samples.
Environmental Fate and Biodegradation of Veterinary Antibiotics and Estrogens
Residues of antibiotics and natural estrogens excreted by animals enter the environment via cropland application of manure that is used as fertilizer. Constant exposure to low levels of antibiotics can lead to the emergence of antibiotic-resistant microorganisms in the environment, while presence of estrogens in surface runoff can cause endocrine disruption in fish in the receiving streams. Due to the potential ecological and human health risks associated with these manure-borne chemicals we are investigating the factors affecting their mobility and persistence in soil. Our research also aims to determine the impact of advanced anaerobic digestion systems in reducing antibiotics, antibiotic resistance genes, and endocrine disrupting chemicals found in animal manure.
Fate and Plant Uptake of Pharmaceuticals from Urine-Based Fertilizers Used in Agriculture
Source separated urine has the potential to become a sustainable nutrient source for agricultural applications. At the same time, removing urine at the source results in lower energy requirements at wastewater treatment plants, a reduction in fresh water consumption from toilets, improvements in wastewater composition that favors biological N removal, and an opportunity to remove contaminants that are concentrated in urine from less complex and reduced volume waste streams. This research will evaluate the feasibility of urine separation technology at the source, and will determine the safety of using precipitated urine as fertilizer for agricultural crops. This approach offers a sustainable and cost-effective step to reducing the amount of pharmaceuticals that reach the aquatic systems, as well as provides a low-cost source of essential nutrients (nitrogen and phosphorous) for crop production. The goals of this research are:  to evaluate the removal efficiency of pharmaceuticals in urine and determine how pretreatments (storage, precipitation) impact degradation of pharmaceutical and biological contaminants;  compare the efficacy of using natural urine and urine derived products (e.g. struvite) as agricultural fertilizers; and  evaluate the potential of agricultural crops to take-up pharmaceuticals.
Treatment of Pharmaceutical Contaminants in Wastewater
Residues of human pharmaceuticals enter the environment from discharges of wastewater treatment plants (WWTP). Our studies focus on the identification of pharmaceutical metabolites resulting from their biodegradation in activated sludge systems. In many cases, we find that the absence of the parent pharmaceutical from the WWTP effluents does not necessarily mean that the compound has been completely eliminated, but instead has only been partially transformed. We are also investigating the efficiency of pharmaceutical removal by advanced oxidation process using UV/H2O2 followed by biofiltration. We have observed that recalcitrant pharmaceuticals can be converted into more biodegradable transformation products by UV/H2O2 treatment. Our study shows that it is important to identify transformation products that are persistent because long-term exposure to some of them may potentially lead to detrimental ecological effects.