Analysis of the Three-Dimensional Fluorescence Spectroscopy Characteristics of Dissolved Organic Matter in Groundwater from a Subtropical Cave in Dry Season—Daxiao Cave in South China Karst

Researchers identified that dissolved organic matter (DOM) in Daxiao Cave's groundwater, a subtropical karst site, is primarily influenced by microbial degradation and subsurface leakage during the dry season. Using three-dimensional fluorescence spectroscopy, parallel factor analysis, and excitation-emission matrix techniques, they found that DOM fluorescence fractions were dominated by humus-like, tryptophan-like, and tyrosine-like components, with protein fluorophores playing a significant role. The study also revealed that Ca–Mg–HCO3 was the dominant hydrochemical type in the cave's drip water, with Ca2+, Mg2+, and HCO3− as key ions. While the exact process linking DOM to water chemistry remains unclear, this research advances understanding of geochemical behavior and sources of DOM in cave systems.

Zhang, R., Liu, Z., Xiong, K., Lyu, X., Hu, C., Wang, X., & Cheng, K. (2021). Analysis of the Three-Dimensional Fluorescence Spectroscopy Characteristics of Dissolved Organic Matter in Groundwater from a Subtropical Cave in Dry Season—Daxiao Cave in South China Karst. Water, 13(24), 3574. https://doi.org/10.3390/w13243574