UV-Vis Absorbance and Fluorescence Characterization of Pasig River Surface Water Samples Towards the Development of an LED Fluorescence Lidar System

Abstract

The status of water quality in Pasig River was studied using UV-Vis absorbance, 3D excitation-emission matrices (EEMs), fluorescence measurements of dissolved organic matter (DOM), and physicochemical parameters measurements. The study was conducted at seven selected sampling stations in Pasig river from April 2019 to June 2019. It has been years since the government has conducted rehabilitation on the Pasig river and we want to determine its current water quality status with the additional information provided by the UV-Vis absorbance and fluorescence spectroscopy. Several surface water samples were collected using the Pasig River ferry system at (St 1) Lawton Station, (St 4) Valenzuela Station, and (St 7) San Joaquin Station. After computing for the absorbance values at 280-nm, 250-nm/365-nm, 253-nm/203-nm, and 226-400, we have used this method to determine the presence of organic carbon and its aromatic substituents. The results showed low humification degree and aromatic structure and vary from April to June 2019. (St 3) shows higher stability organic molecules containing benzene ring structures. A seasonal variability has been observed from the water quality parameters, which is also present from the fluorescence measurements. DOM sources were measured using fluorescence index (FI), the results showed that all surface water samples were terrestrially derived DOM concentrations. The variance can be attributed to the effluents from the land use types near the sampling stations such as industrial and residential waste. Based on the water quality, absorbance and fluorescence results, the impact of marine waters greatly affects the characterization and production of organic materials.