Optical Characteristics of Dissolved Organic Matter from Two Different Full Mixed Reservoirs in Winter Based on UV-vis and EEMs

Abstract

The differences in the resource and characteristics of DOM between Zhoucun Reservoir and Jinpen Reservoir were studied by fluorescence ultraviolet-visible (UV-vis) and excitation-emission matrix spectra combined with parallel analysis (EEMs-PARAFAC). The results showed that three fluorescent components were identified by PARAFAC model in Zhoucun Reservoir and Jinpen Reservoir, including long wave humus-like component (C1: 350/460 nm), visible fulvic-like (C2: 335/410 nm) and protein-like (C3: 260,285/360 nm). However, the fluorescence intensity and the relative proportions of DOM exhibited significant difference (P<0.01) in two reservoirs. Moreover, the concentration of protein-like component in Zhoucun Reservoir was higher than that in Jinpen Reservoir, while the concentration of humus-like component presented the opposite trend. Based on the comparison of fluorescence index, biological index, humification index and the freshness index, the DOM of Zhoucun Reservoir where the land-use type was cultivated, livestock and residential, the internal pollution of sediments was serious, indicating a strong autochthonous component and aquatic bacterial origin, whereas the DOM of Jinpen Reservoir dominated by forest system had a higher terrigenous contribution in winter. From all the results, hydrological conditions of the reservoir and the characteristics of coastal ecological environment were important factors to influence the DOM sources and characteristics.