ORIGINS OF OPTICAL PROPERTIES IN NATURAL ORGANIC MATTER AND FLUORESCENT ANIMALS

Abstract

Dissolved organic matter (DOM) is a complex mixture of naturally occurring organic molecules originating from multiple marine and terrestrial sources. DOM plays a significant role in water quality by affecting the photochemistry, trace metal transport, and acidity in aquatic systems. Understanding the chemical composition of DOM helps interpret the links between its optical properties and molecular structures. Currently, the molecular origins of the optical properties of DOM are not well-defined. In addition, characterizing DOM has been challenging because of its complex, heterogeneous nature and dynamic nature while continuously undergoing photochemical and microbial degradations. In the present work, we use simple aromatic precursors to undergo oxidative steps and reproduce the optical properties of DOM. UV-visible and fluorescence spectroscopy are used alongside mass spectrometry to provide evidence that simple precursors form oligomeric chromophores mimicking the optical properties of DOM. The findings in this study help understand the links between the optical and molecular characteristics of DOM. In addition, the origins of optical properties in multiple nocturnal animals due to the accumulation of porphyrin byproducts are elucidated by combining UV-visible, fluorescence spectroscopy, and liquid chromatography (LC)/mass spectrometry (MS) analyses.