Absorption and Three Dimensional Fluorescence Spectra of CDOM in the Water of the Taibaishan Nature Reserve

Abstract

It is very important to understand water ecology and the carbon cycle process by studying the composition, source, spectral characteristics, and influence factors of chromophoric dissolved organic matter (CDOM). The optical characteristics, composition, and source of CDOM in 71 water samples were collected from the lakes and four rivers of the Taibaishan Nature Reserve in the summer of 2019. The rivers included the Bawang, Heihe, Shitou, and Xushui Rivers. They were analyzed by UV-Vis spectral and three-dimensional fluorescence spectroscopy, combined with a parallel factor analysis model and redundant analysis. The results showed that CDOM in the water of the Taibaishan Nature Reserve contained two types of four fluorescent components, in which the humus-like components C1 and C2 were the main components of CDOM. The relative contribution of C1 and C2 to the rivers was 82%-96%, which was significantly larger than the lakes. All fluorescence indexes (FI) were larger than 1.8, the index of recent autochthonous contribution (BIX), and the index of freshness (β:α) were all approximately 0.6. The humification indexes (HIX) of the rivers were significantly larger than those of the lakes (P<0.01). The DOM in the rivers was mainly from the forest soil of the Nature Reserve, and the water quality of the lakes was affected by tourists to some extent. The results of the redundant analysis show that the CDOM spectral characteristic parameters were significantly influenced by EC for the lakes (P<0.05) and by EC, DTN, and DOC for the rivers (P<0.01).