Effect of prescribed fires on the export of dissolved organic matter, precursors of disinfection by-products, and water treatability

Habibullah Uzun; Wenbo Zhang; Christopher I Olivares; Cagri Utku Erdem; T Adam Coates; Tanju Karanfil; Alex T Chow

doi:10.1016/j.watres.2020.116385

Effect of prescribed fires on the export of dissolved organic matter, precursors of disinfection by-products, and water treatability

Water Res. 2020 Dec 15:187:116385. doi: 10.1016/j.watres.2020.116385. Epub 2020 Sep 3.

Authors

Habibullah Uzun¹, Wenbo Zhang², Christopher I Olivares³, Cagri Utku Erdem⁴, T Adam Coates⁵, Tanju Karanfil⁴, Alex T Chow⁶

Affiliations

¹ Department of Environmental Engineering, Marmara University, Istanbul 34722, Turkey.
² Biogeochemistry & Environmental Quality Research Group, Clemson University, Georgetown, SC 29442, United States.
³ Department of Civil and Environmental Engineering, University of California-Berkeley, Berkeley, California 94720, United States.
⁴ Department of Environmental Engineering and Earth Sciences, Clemson University, Anderson, South Carolina 29625, United States.
⁵ Department of Forest Resources and Environmental Conservation, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States.
⁶ Biogeochemistry & Environmental Quality Research Group, Clemson University, Georgetown, SC 29442, United States; Department of Environmental Engineering and Earth Sciences, Clemson University, Anderson, South Carolina 29625, United States. Electronic address: achow@clemson.edu.

PMID: 32949825
DOI: 10.1016/j.watres.2020.116385

Abstract

In this study, we report for the first time the effect of prescribed fires on the export of dissolved organic matter (DOM) and precursors of disinfectant by-products (DBPs) from periodically (every 2-3 years) and seasonally (i.e., dormant and growing) burned forest fuel materials (i.e., live vegetation, woody debris, and detritus [litter and duff]) and treatability of its rainwater leachate. Periodically applied (every 2-3 years for 40 years) prescribed fires decreased total fuel load (62±10%), primarily detrital mass (75±2%). However, functional groups (i.e., phenolic compounds, proteins, carbohydrates, aromatic [1-ring], polycyclic aromatic hydrocarbons [PAHs], and lipids) attached to DOM of ground solid materials did not change significantly. Outside rainwater leaching (from forest fuel materials) experiments showed that the leaching capacity of dissolved organic carbon (DOC) from burned litter samples decreased by 40±20% regardless of burning season when compared to unburned litter samples. The leaching of total dissolved nitrogen (TDN), dissolved organic nitrogen (DON), ammonium (NH₄⁺), and reactive phosphorus (PO₄^3-) from burned materials decreased between 40 and 70% when compared to unburned materials. Also, DOM composition was affected by prescribed fire, which partially consumed humic-like substances based on fluorescence analyses. Thus, periodically applied prescribed fires also resulted in a reduction of trihalomethane (THM) (42±23%) and haloacetic acid (HAA) (42±20%) formation potentials (FPs), while DOC normalized reactivity of THM and HAA FPs did not change significantly. Additionally, the leaching of N-nitrosodimethylamine (NDMA) precursors, bromide ion (Br^-), and selected elements (K, Ca, Mg, Mn, Fe, S, Na, B, and Al) were not significantly affected by prescribed fires. Finally, coagulant (i.e., alum and ferric) dose requirements and coagulation efficiencies were similar (i.e., removal of DOC, precursors of THMs and HAAs were 52-56%, 69-70%, 78-79%, respectively) in unburned and pre-burned leachate samples.

Keywords: Coagulation; DBP precursors; DOM leaching and composition; Prescribed fire.

MeSH terms

Disinfection
Nitrogen / analysis
Trihalomethanes / analysis
Water
Water Pollutants, Chemical* / analysis
Water Purification*

Substances

Trihalomethanes
Water Pollutants, Chemical
Water
Nitrogen