ИСТИНА

Dissolved organic matter (DOM) plays an important role in the environment by supporting growth of marine biota and participating in flocculation of colloid clay particles in estuarine zones; it also indicates terrestrial processing of organic matter. One of the most informative methods of DOM analysis is two-dimensional spectrofluorometry, characterized by high sensitivity, minimal sample preparation and a small sample volume required for analysis. It is usually not possible to discern separate emission lines corresponding to individual compounds in DOM fluorescence spectra, so instead, a small number of fluorophores with defined optical characteristics is described and correlated to allochthonous protein-like compounds or terrigenous humic substances. Tensor rank decomposition methods (e.g. PARAFAC) are successfully employed to find the independent components (considered to be correlated to fluorophores) comprising each individual excitation-emission matrix (EEM) in the dataset. There is still only fragmentary information on PARAFAC components of EEMs of Arctic seawater. In this work, 150 samples of DOM from Arctic shelf seas and freshwater ponds of Novaya Zemlya archipelago were collected during the cruises 2015-2018. EEMs were recorded in wide ranges of excitation (230–550 nm) and emission (240–650 nm) wavelengths. Different methods of signal normalization were applied. Due to hardware limitations, the data contained unfiltered scattering peaks which had to be removed from the dataset to build an accurate PARAFAC model. CORCONDIA and split-half analysis were used to choose an appropriate number of components. Selected components correlate well with conventional HIX and BIX indices confirming the sufficiency of the model. Acknowledgement: This work is supported by the Russian Foundation for Basic Research, grant No 16-35-60032 mol_a_dk.