Fluorescence and absorbance indices for chromophoric dissolved organic matter (CDOM) occurring in the stratified lakes at the coast of the White Sea
Chromophoric dissolved organic matter (CDOM) of natural origin is one of the most important components of marine ecosystems and the carbon cycle. The goal of the present study is to investigate the distribution and fluorescence of DOM in different water layers of separated lakes of the White Sea. The spectral-optical properties of CDOM occurring in water of the coastal meromictic water bodies have been studied for the last 5 years. In this period of time the absorption and fluorescence spectra of CDOM from various depths were measured, the spectroscopic indices based on absorbance values and fluorescence emission data were calculated, a fluorescence quantum yield and its dependence on the excitation wavelength were counted. The spectral characteristics of CDOM are in good agreement with the hydrochemical properties of water. Due to the influx of swamp water surface water contains more humic substances and, accordingly, a higher optical density in the UV region, a smooth monotonic decrease in the absorption spectrum in the UV region and an intensive fluorescence. The lower layers of salt water are characterized by the spectral-optical properties similar to CDOM of marine origin.
This work was supported by the RFBR grants No. 19-05-00056 and 19-05-00377. The author A.A. Zhiltsova was also supported by the Foundation for the advancement of theoretical physics “BASIS”.
Department of Physics, Moscow State University, 119992, Moscow
File with report