Disinfection byproducts formed during drinking water treatment reveal an export control point for dissolved organic matter in a subalpine headwater stream

Laura T Leonard; Gary F Vanzin; Vanessa A Garayburu-Caruso; Stephanie S Lau; Curtis A Beutler; Alexander W Newman; William A Mitch; James C Stegen; Kenneth H Williams; Jonathan O Sharp

doi:10.1016/j.wroa.2022.100144

Disinfection byproducts formed during drinking water treatment reveal an export control point for dissolved organic matter in a subalpine headwater stream

Water Res X. 2022 Apr 25:15:100144. doi: 10.1016/j.wroa.2022.100144. eCollection 2022 May 1.

Authors

Affiliations

¹ Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, United States.
² Pacific Northwest National Laboratory, Richland, WA 99354, United States.
³ Stanford University, Stanford, CA 94305, United States.
⁴ Rocky Mountain Biological Laboratory, Gothic, CO 81224, United States.
⁵ Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States.
⁶ Hydrologic Science and Engineering Program, Colorado School of Mines, Golden, CO 80401, United States.

Abstract

Changes in climate, season, and vegetation can alter organic export from watersheds. While an accepted tradeoff to protect public health, disinfection processes during drinking water treatment can adversely react with organic compounds to form disinfection byproducts (DBPs). By extension, DBP monitoring can yield insights into hydrobiogeochemical dynamics within watersheds and their implications for water resource management. In this study, we analyzed temporal trends from a water treatment facility that sources water from Coal Creek in Crested Butte, Colorado. These trends revealed a long-term increase in haloacetic acid and trihalomethane formation over the period of 2005-2020. Disproportionate export of dissolved organic carbon and formation of DBPs that exceeded maximum contaminant levels were consistently recorded in association with late spring freshet. Synoptic sampling of the creek in 2020 and 2021 identified a biogeochemical hotspot for organic carbon export in the upper domain of the watershed that contained a prominent fulvic acid-like fluorescent signature. DBP formation potential analyses from this domain yielded similar ratios of regulated DBP classes to those formed at the drinking water facility. Spectrometric qualitative analyses of pre and post-reacted waters with hypochlorite indicated lignin-like and condensed hydrocarbon-like molecules were the major reactive chemical classes during chlorine-based disinfection. This study demonstrates how drinking water quality archives combined with synoptic sampling and targeted analyses can be used to identify and understand export control points for dissolved organic matter. This approach could be applied to identify and characterize analogous watersheds where seasonal or climate-associated organic matter export challenge water treatment disinfection and by extension inform watershed management and drinking water treatment.

Keywords: Climate change; Disinfection byproducts; Organic matter; Water quality; Water treatment; Watershed.