Parallel factor analysis of fluorescence EEM spectra to identify THM precursors in lake waters.

Dissolved organic matter (DOM) can react with chlorine and yield undesirable disinfection byproducts (DBPs), e.g., trihalomethanes (THMs). Numerous studies have demonstrated that various DOM constituents have DBP formation potentials. We explored in this study the use of fluorescence excitation-emission (EEM) spectroscopy to identify THM precursors in 55 lakes in Missouri, USA. EEMs of the lake waters were decomposed into five factors of different origins through parallel factor analysis. The correlations between the component scores of the factors and THM formation potentials reveal that factors 1 and 2 are likely THM precursors and provided better surrogates than SUVA (dissolved organic carbon-normalized UV254) for predicting DBP formation potential. Thus, monitoring the component scores of the DOM-origin factors would provide a practical tool to identify THM precursors and facilitate utilities to choose appropriate techniques for DBP mitigation and optimize the degree of water treatment.