UNS: Collaborative Research: Characterizing pyrogenic soil organic matter as a source of nitrogenous disinfection byproducts

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1512705 / 1512670 Rosario-Ortiz / Young With the increasing frequency and extent of wildfires, understanding the effect of wildfires on disinfection byproduct formation potential will provide a foundation for drinking water utilities to adapt to changes in affected watersheds. Wildfires chemically transform soil organic matter, and mountainous slopes are more prone to erosion after wildfires. Increased sediment transport can lead to increased deposition and accumulation of pyrogenic soil organic matter in surface waters (i.e., rivers and lakes), and the concern is that dissolved organic matter characteristics from wildfires affects the formation of disinfection byproducts. The results from this research will provide beneficial information for utility operators, managers, researchers, and regulators.Wildfires in forested watersheds transform ecosystems and affect surface water quality. Previous work by the principal investigator (PI) demonstrated that leachates from sediments in wildfire-impacted areas have a greater potential (i.e., increased yield of disinfection byproducts) to form haloacetonitriles after chlorination. Haloacetonitriles, along with other nitrogenous disinfection byproducts, are an emerging area of concern. Although not yet regulated by the USEPA, haloacetonitriles and haloacetamides are more toxic than regulated carbonaceous disinfection byproducts. The proposed study investigates the effect of thermal processes on the formation of nitrogenous disinfection byproducts (haloacetonitriles and haloacetamides) from soil organic matter. Soil organic matter is nitrogen-rich, containing peptide-like material from in situ microbial processes. Soil organic nitrogen is transformed into cyclic dipeptides and heterocyclic aromatic compounds by thermal processes. The objectives are to simulate the transformation of organic matter due to thermal processes, leaching into surface water, and the formation of disinfection byproducts during disinfection processes. Samples will be collected from burned and unburned locations within a wildfire-impacted watershed. Organic nitrogen characterization (i.e., amino acid and NMR analysis) will be used to elucidate which organic nitrogen characteristics are associated with increased haloacetonitriles and haloacetamide formation. In addition to high quality publications, the students involved in this research will have the opportunity to operate the analytical equipment required to produce the needed data during the new Laboratory class that will be designed as an outcome of this project. This will enhance the quality of the teaching and training derived from this proposal. Additionally, the PI is committed to promote the dissemination of these research results through several organizations, such as the Front Range Drinking Water Consortium and the Water Research Foundation.