Characterization of Dissolved Organic Matter in Lake Baiyangdian Using Spectroscopic Techniques and Multivariate Statistical Analysis

Abstract

Dissolved organic matter (DOM) collected from the surface and overlying waters in different functional regions in Lake Baiyangdian were analyzed by spectroscopic techniques combined with principal component analysis (PCA) and hierarchical cluster analysis (HCA), to interpret water quality, and sources of pollutants. The results showed that the deterioration of water quality has intensified at river estuary and aquaculture area. Meanwhile, these regions dominated by plants had relatively low dissolved oxygen concentrations. UV-vis spectra showed lower humification degree and simpler molecular structure in the DOM collected from the pollutant-receiving region. The analysis of PCA combined with synchronous fluorescence spectra yielded two principal components (PCs) that account for 99.44% of the variance. PC1 showed a dominant protein-like fluorophore at 279 nm and PC2 was characterized by dominated fulvic-like fluorophores (325 and 331 nm). The results of PCA indicated that DOM collected from the river estuary, the aquaculture region, and the eutrophication area exhibited a higher protein-like fluorophore, and higher PC1 and lower PC2 loadings (PC1 > 0.7, PC2 < 0.4). Meanwhile, a higher fulvic-like fluorophore existed in the DOM samples collected from a clean region (PC1 < 0.4, PC2 > 0.7). HCA identified four clusters that accorded with the PCA results. This study suggested that water quality and the sources, and spectral characteristics of DOM were influenced mainly by human activities (agriculture, industrial, and domestic wastewater from upstream, food and excrement from aquaculture) and natural processes (aquatic-plant and microorganism activities).

Recognizing Dissolved Organic Matter with an Improved Fluorescence Regional Integral Method

“…The core principle of this method involves generating a 3DEEMS image by sending fluorescence spectra intensity at given excitation and emission wavelengths on a plane as abscissa that ordinate with one another in order to distinguish different kinds of DOM (Coble et al, 1990). Cui et al (2016) researched the constitution and features of resolvable matters in the Baiyangdian District through 3DEEMS. He et al (2015) researched the origin and constitution of resolvable organic matter in the groundwater polluted by leachate using 3DEEMS in tandem with chemical analysis.…”