Education

B.S., 1984, Georgia College & State University
Ph.D., 1989, Emory University

Honors and Awards

Walter J. Weber, Jr. Association of Environmental Engineering and Science Professors (AEESP) Frontier in Research Award, 2021; Analytical Scientist Power List, 2021; Herty Medal, 2020; Southern Chemist Award (American Chemical Society), 2020; Fellow of the American Association for the Advancement of Sciences, 2019; Fellow of the American Chemical Society, 2016; American Chemical Society Award for Creative Advances in Environmental Science & Technology, 2008;  Honorary Doctorate (Doctor of Letters, honoris causa), Cape Breton University, Sydney, Nova Scotia, Canada, 2006.

Research

Environmental analytical chemistry; drinking water disinfection by-products (DBPs); emerging environmental contaminants; per- and poly-fluorinated alkyl substances (PFAS); total organic fluorine; microplastics; pharmaceuticals; impacts of algae on drinking water and human health; new analytical methods and technologies; novel technologies to remove emerging contaminants; mass spectrometry.

Introduction: My research is interdisciplinary (often combines chemistry, toxicology, and engineering) and focuses mostly on improving the safety of drinking water. Recent work also includes development of new analytical methods and technologies to measure contaminants in the environment. Examples include (1) Total Organic Fluorine methods we created to allow a comprehensive assessment of PFAS in industrial wastewater, river water, and air; and (2) Highly sensitive GC-MS(/MS) methods to quantify 72 DBPs in drinking water. Mass spectrometry is one of the main tools we use in our research to identify new environmental contaminants and to quantify contaminants.

Background: Drinking water disinfection was a triumph of the 20th Century, allowing the prevention of many waterborne illnesses, however, an unintended consequence is the formation of DBPs in drinking water. Human epidemiologic studies show some adverse health effects from DBPs, yet the DBPs responsible for these effects are still not completely understood. DBPs are different from other traditional contaminants, being formed when disinfectants (e.g., chlorine, chloramines, ozone, and chlorine dioxide) react with naturally occurring organic matter, bromide, and iodide. They can also form through the reaction of disinfectants with anthropogenic contaminants, such as pharmaceuticals.

One of the most important studies of my career involved the discovery of “Forcing Factors” of toxicity in drinking water (Allen et al., 2022), where we discovered that haloacetonitrile and iodo-acid DBPs were the main drivers of toxicity in U.S. drinking waters.  In addition, we recently identified an entirely new class of DBPs: halocyclopentadienes, which are toxic and predicted to be bioaccumulative (a “first” for DBPs) (Li et al., 2022). We also discovered that the use of iodized  

salt in cooking pasta can result in the formation of iodinated DBPs during cooking (Dong et al., 2023). In addition, we recently contributed to important discoveries for the impacts of algae on drinking water and human health, including the identification of natural algal metabolites that may be responsible for auto-immune issues, such as lupus and rheumatoid arthritis, as well as the discovery of 2-fold DBP concentrations and increased nitrogenous DBPs in drinking water when algae is present in water sources.

Experimental approach: We use gas chromatography (GC)-mass spectrometry (MS) and liquid chromatography (LC)-MS/MS techniques to identify and measure DBPs and other transformation products in drinking water and wastewater. Mass spectrometry is an ideal analytical tool for measuring trace levels of compounds in complex environmental matrices, and we utilize several different ionization modes as well as high resolution-MS. We currently have 6 mass spectrometers in my laboratory and have access to several others in our department’s Mass Spectrometry Center. We are also using a new technology called Vacuum-Assisted Sorbent Extraction (VASE) with GC-MS to more comprehensively extract contaminants from water, as well as total organic halogen (TOX) analysis and ion chromatography. 

Current research: My current research continues to investigate DBPs, novel algal toxins from harmful algal blooms, and transformation of emerging contaminants during advanced oxidation treatment for water reuse, including a new UV/Cl₂ treatment. In addition, we are currently using mass spectrometry to identify contaminants in real-world microplastics, assessing PFAS hotspots in the state of South Carolina (using new TOF methods created in our laboratory), and even participating in an archaeology study to identify biomarkers in traditional ceremonial drinks from indigenous people in Central America to help determine when residues of these are present in ancient pots discovered.  Finally, we are also developing new analytical methods to enable improved extraction and measurement of contaminants in complex matrices.

Selected Publications

Mitch, W.A., S. D. Richardson, X. R. Zhang, and M. Gonsior. High-Molecular-Weight By-Products of Chlorine Disinfection. Nature Water 2023, 1, 336–347. https://doi.org/10.1038/s44221-023-00064-x. (Invited).

Forster, A. L. B., Y. Zhang, D. C. Westerman, and S. D. Richardson. Improved Total Organic Fluorine Methods for More Comprehensive Measurement of PFAS in Industrial Wastewater, River Water, and Air.  Water Res. 2023, 235, 119859. https://doi.org/10.1016/j.watres.2023.119859.

Dong, H., I. D. Nordhorn, K. Lamann, D. C. Westerman, H. K. Liberatore, A. L. B. Forster, M. T. Aziz, and S. D. Richardson. Overlooked Iodo-Disinfection Byproduct Formation When Cooking Pasta with Iodized Table Salt. Environ. Sci. Technol. 2023, 57 (9): 3538-3548. https://doi.org/10.1021/acs.est.2c05234.

Li, J., M. T. Aziz, C. O. Granger, and S. D. Richardson. Halocyclopentadienes: An Emerging Class of Toxic DBPs in Chlor(am)inated Drinking Water. Environ. Sci. Technol. 2022, 56, 11387–11397. https://doi.org/10.1021/acs.est.2c02490.

Allen, J. M., M. J. Plewa, E. D. Wagner, X. Wei, K. Bokenkamp, K. Hur, A. Jia, H. K. Liberatore, C.-F. T. Lee, R. Shirkhani, S. K. Krasner, and S. D. Richardson. Disinfection By-Product Drivers of Cytotoxicity in U.S. Drinking Water: Should Other DBPs Be Considered for Regulation? Environ. Sci. Technol. 2022, 56, 392−402. 

Cuthbertson, A. A., H. K. Liberatore, S. Y. Kimura, J. M. Allen, A. V. Bensussan, and S. D. Richardson. Trace Analysis of 61 Emerging Br‑, Cl‑, and I‑DBPs: New Methods to Achieve Part-Per-Trillion Quantification in Drinking Water. Anal. Chem. 2020, 92 (4), 3058-3068. https://doi.org/10.1021/acs.analchem.9b04377.

Liberatore, H. K., D. C. Westerman, J. M. Allen, M. J. Plewa, E. D. Wagner, A. M. McKenna, C. R. Weisbrod, J. P. McCord, R. J. Liberatore, D. B. Burnett, L. H. Cizmas, and S. D. Richardson. High-Resolution Mass Spectrometry Identification of Novel Surfactant-Derived Sulfur-Containing Disinfection By-Products from Gas Extraction Wastewater. Environ. Sci. Technol. 2020, 54, 9374−9386.https://pubmed.ncbi.nlm.nih.gov/32600038/

Powers, L. C., A. Conway, C. L. Mitchelmore, S. J. Fleischaker, M. Harir, D. C. Westerman, J. P. Croué, P. Schmitt-Kopplin, S. D. Richardson, and M. Gonsior. Tracking the Formation of New Brominated Disinfection By-Products during the Seawater Desalination Process. Environ. Sci. Water Res. Technol. 2020, 6, 2521-2541. https://doi.org/10.1039/D0EW00426J.

Huang, Y., M. Kong, S. Coffin, K. H. Cochran, D. C. Westerman, D. Schlenk, S. D. Richardson, L. Lei, and D. D. Dionysiou. Degradation of Contaminants of Emerging Concern by UV/H2O2 for Water Reuse: Kinetics, Mechanisms, and Cytotoxicity Analysis. Water Res. 2020, 174, 115587. https://doi.org/10.1016/j.watres.2020.115587.

Richardson, S. D., and S. Y. Kimura. Water Analysis: Emerging Contaminants and Current Issues. Anal. Chem. 2020, 92 (1), 473-505. https://doi.org/10.1021/acs.analchem.7b04577.