Characterization of water quality and fluorescence measurements of dissolved organic matter in Cabuyao river and its tributaries using excitation-emission matrix spectroscopy

Abstract

Laguna lake is an important natural resource that provides agricultural and other uses such as transportation, recreation, and irrigation. Due to rapid changes in the land use near the west region of Laguna lake, surface water quality measurements are necessary. Using excitation-emission fluorescence spectroscopy, the optical characteristics of dissolved organic matter (DOM) in Cabuyao river were assessed. There are six sampling sites based on inflow and outflow of water from Cabuyao river and its tributaries. 3D excitation-emission matrices (EEMs) using Surfer v16 was utilized in the assessment of protein-like and humic-like fluorescence peaks. It was observed that the differences in the EEMs provided DOM composition, and its origin. A fluorescence index of approximately 1.18 showed that most of the samples are terrestrial in origin. In-situ water quality measurements such as dissolved oxygen, temperature, pH, and electrical conductivity. Hence, this study provides preliminary information on the possible use of fluorescence EEMs in providing DOM composition in natural waters.