Characteristics and disinfection byproducts formation potential of dissolved organic matter released from fast-growing Eucalyptus urophylla leaves

Abstract

Every year, the harvesting of Eucalyptus generates a large amount of abandoned Eucalyptus leaves (ELs), which may release dissolved organic matter (DOM) when immersed in water. If these substances are carried by surface runoff directly to the source of drinking water, some components in the DOM tend to form disinfection byproducts (DBPs) within the water-supply system, posing risk to human health. In this study, the characteristics of DOM released from leaves of Eucalyptus urophylla were studied and the potential of DBPs formation of the EL-released DOM during the chlorination process was investigated. The results showed that the EL-released DOM was mainly composed of small molecules and hydrophobic substances. Of the total EL-released DOM, the proportion with molecular weight less than 10 kDa accounted for over 80% and the hydrophobic substances took up over 62%. The DOM showed strong absorbance at UV₂₅₄ and the fluorescence response corresponding to humic acid-like (HA-like) fractions, soluble microbial byproduct-like, aromatic protein and fulvic acid-like (FA-like) material, which have been considered to be related to the potential precursors of chlorinated DBPs. Non-targeted screening demonstrated the presence of phenolics, carbohydrates, and amino acids. The analysis of products generated in chlorination process revealed the formation of trichloromethane (TCM) and the total organic halogen (TOX). The present study fully confirms that the DOM released from Eucalyptus urophylla leaves has great potential for the generation of chlorinated DBPs.

Keywords: Chlorinated disinfection byproducts; Dissolved organic matter (DOM); Eucalyptus leaves (ELs); Fluorescence EEM; Non-targeted screening; Potential.