Sources, composition, and spectroscopiccharacteristics of dissolved organic matter extractedfrom sediments in an anthropogenic-impacted riverin Southeastern China

Abstract

The fluorescence and ultraviolet spectroscopic characteristics of dissolved organic matter extracted from sediments in an anthropogenic-impacted river (Hao River) in Southeastern China were analyzed in the current study. Excitation–emission matrix (EEM) fluorescence combined with parallel factor analysis (PARAFAC) was conducted to analyze the sources and composition of dissolved organic matter (DOM). The average dissolved organic carbon (DOC) concentrations of all samples at depths of 0–10, 10–20, and 20–30 cm were 317, 319, and 319 mg kg⁻¹ dry weight, respectively. Four components were identified from the fluorescence spectra that consisted of three humic-like components (C1, C2, and C3) and one protein-like component (C4). Component C1 was derived from terrestrial plants and soils. Component C2 in the anthropogenic-impacted Hao River was derived from anthropogenic pollution such as wastewater. Component C3 comprised refractory particles derived from terrestrial plants. Component C4 was autochthonous and produced by the aquatic ecosystem. With the exception of site 4, all sites could be assigned to one of two groups. Group 1 consisted of sites 1, 2, 3, and 5, and group 2 consisted of sites 6, 7, and 8. Our result showed that the sediment in group 2 was more anaerobic than in group 1. Consequently, it could be concluded that this river was polluted by both point and non-point pollution. The terrain slopes cause that water flows from the Yangzi River into group 1. The dilution effect in group 1 resulted in less accumulation of DOM in the sediment of group 1 than group 2.

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