The spectral characteristics of dissolved organic matter from sediments in Lake Baiyangdian, North China

Dissolved organic matter (DOM) extracted from sediment samples in Lake Baiyangdian was investigated using UV -Vis absorption and fluorescence spectroscopy. Two parameters, the ratios of absorbance and dissolved organic carbon at 254° nm (SUVA254) and the integral area from 240° nm to 400° nm (A240 -400), were used to assess the molecular weight and aromaticity of DOM. The surface sediments showed a relatively low aromaticity of DOM due to the impact of environmental pollution. Synchronous fluorescence spectra showed an extremely high fraction of the protein-like region (PLR). Parallel factor analysis (PARAFAC) of excitation -emission matrix spectra revealed four fluorescent components occurring in sediment DOM: two humic-like (C1 and C2) components and two protein-like (C3 and C4) components. The PARAFAC-PCA displayed three PCA factors (factors 1, 2 and 3) which accounted for 48.250%, 25.927% and 25.391%, respectively, of the variance in fluorescent component. The humic-like components 1 and 2 concurrently showed positive factor 1 loadings. Factor 2 was mainly explained by the tryptophan-like component C3. A non-humic component 4, having a low factor loading in the other two factors, showed an extremely high factor 3 loading. The EEM -PARAFAC-PCA showed varying contributions of terrestrial versus autochthonous DOM sources in lake sediments.