Fluorescence Fingerprint of Waters: Excitation-Emission Matrix Spectroscopy as a Tracking Tool

Abstract

In this report, an optical method for tracking sources of water entering rivers and oceans is applied to the Congaree River in Columbia, South Carolina. The Congaree River forms at the confluence of two rivers, the Saluda and the Broad. Excitation-emission matrix (EEM) spectra of water samples from the rivers were constructed by scanning emission spectra from 300 to 600 nm as a function of excitation wavelength from 200 to 290 nm. The two sources of water in the Congaree River were easily distinguishable on the basis of the EEM spectra of the water samples. In addition, the average composition of water in the Congaree River and hence the relative flow rates of inflowing Saluda and Broad Rivers could be determined. In this report, the characteristic fluorescence of the river water samples and the stability of the EEM spectra of the river samples over several months are presented.