The migration and transformation processes of dissolved organic matter in rainwater- drip water- phreatic water of a typical karst spring catchment, in South China

Characteristics and Influencing Factors of Dissolved Organic Matter in Cave Drip Water—A Case Study from Furong Cave, Southwest China

“…Overall, the average HIX values for MP1, MP2, MP3, and MP9 during the dry season were 0.65, 0.66, 0.65, and 0.50, respectively (Table S6), while during the rainy season, they were 0.60, 0.62, 0.64, and 0.47, respectively (Table S6). These HIX values indicate an endogenic nature, with a low humification degree of dissolved organic matter (DOM) due to dilution effects from rainfall [3]. During the dry season, microbial activity tends to decompose small organic molecules in DOM, leading to an accumulation of larger organic molecules [42,83,84], resulting in a similar level of humification degree between the dry and rainy seasons for DOM.…”

“…The unique geological structures in karst regions facilitate the infiltration of surface pollutants into the underlying aquifers through the overlying soil or fractures, resulting in the contamination of groundwater resources [2]. The transport of solutes is typically controlled by hydrological processes in karst areas, highlighting the significance of understanding hydrological processes within karst regions [3].…”

“…Similar to the proxies of oxygen and carbon isotopes and trace elements in stalagmites, understanding the significance of organic matter in stalagmite paleoclimate reconstruction through modern cave monitoring and deciphering the signal transmission and mechanisms of organic matter in karst systems is particularly important. Long-term monitoring studies in caves have primarily focused on stable isotopes (δ 18 O, δ 13 C) [12][13][14][15][16] and trace elements (Mg, Ca Ba Sr) as representatives of inorganic geochemical processes with climatic implications [17][18][19][20]; relatively less attention has been paid to organic geochemical processes [3,[21][22][23][24]. Currently, the modern monitoring of organic matter in caves has been limited in duration, with the majority of studies focused on investigating the mechanisms behind the formation of fluorescent luminescence laminae in stalagmites [10,25,26].…”

“…Previous studies have been conducted on rainwater DOM in karst and non-karst areas [3,43,44], as well as the DOM in drip water [3,27,45,46]. However, the transport mechanism of DOM is especially intricate due to the influence of hydrogeological processes on its composition [45].…”

“…Parallel factor analysis (PARAFAC) is utilized to qualitatively and quantitatively extract information from excitation-emission matrices (EEM) [50,51]. By coupling three-dimensional excitation-emission matrices with fluorescence regional integration (3D-EEM-FRI), spectral information identification and the characterization of multi-component fluorescence spectra can be achieved [3,52].…”