Molecular-Level Insights into the Formation of Traditional and Novel Halogenated Disinfection Byproducts

Abstract

Dissolved organic matter (DOM) composition influences the formation of disinfection byproducts (DBPs) during drinking water treatment, yet the role of DOM composition at the molecular level in forming both known and novel DBPs has not been established. We characterized the composition of DOM from drinking water utilities that draw from surface (n = 4) and groundwaters (n = 14), focusing on groundwater because the reactivity of its DOM is poorly understood. We quantified the formation of targeted DBPs, identified novel high molecular weight (HMW) halogenated DBPs, and analyzed DOM transformation after reaction with free available chlorine. Characterization by UV−visible spectroscopy and Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) reveals a high degree of variability in DOM composition and reactivity with chlorine, particularly among groundwater samples. Despite the variability in DOM composition, novel DBPs with up to three halogens are compositionally similar among all waters and are positively correlated with trihalomethane and, to a lesser extent, haloacetonitrile formation. These relationships demonstrate that some low molecular weight DBPs and novel DBPs detected by FT-ICR MS share similar aromatic precursors, providing evidence that DBPs such as trihalomethanes are a useful proxy for the formation of their HMW counterparts.

Does Snowfall Introduce Disinfection By-product Precursors to Surface Water?

“…69 Overall, there was a large variability between surface water and meltwater. For surface water, similar to previous studies, 70,71 CHO compounds made up a larger proportion in the DOM, accounting for about 60% of the 3591 molecular formulas, while the proportions of nitrogenous and sulfurous organics (CHON, CHONS, and CHOS) were relatively low (Figure S9a). In contrast, the proportions of nitrogenous and sulfurous organics in meltwater-derived DOM (∼67%) were significantly higher than those in surface water DOM (∼39%) due to the prevalence of nitrogen and sulfur in atmospheric pollutants, 72 and the proportions of nitrogen-containing organics increased slightly in snow-impacted surface water.…”

Mass Difference Matching Unfolds Hidden Molecular Structures of Dissolved Organic Matter

“…We chose the structural domains reprinted in the 2014 review by Minor et al for reference because this represents the general level of detail and type of classes distinguished in recent DOM studies (Figure S-4). ,,− In two separate analyses, formulas were also classified with a more general and a data-based van Krevelen scheme besides the reference one. , …”

Mass difference matching unfolds hidden molecular structures of dissolved organic matter

“…We chose the structural domains reprinted in the 2014 review by Minor et al for reference, because this represents the general level of detail and type of classes distinguished in recent DOM studies (Figure S-3). 58,[68][69][70] In a separate analysis, lignin-like and N-and S-containing formulas were also classified with a more general Van Krevelen scheme besides the reference one. 71 Finally, we assessed the agreement between structures predicted by Δm matching and those suggested in natural product structural databases.…”