Fatty acid sources and distributions in typical karst river water and groundwater: Insights from hydrochemistry and microbial traces
| 作者 | Zuobing Liang1,3,Shaoheng Li1,2,Pengcheng Zhang5, Rui Li4 ,Qirui Wu4 ,Zaizhi Yang1,Di Tian1,Kun Ren1,6,Lei Gao4 ,Jianyao Chen1 |
| 刊物 | Environmental Earth Sciences |
| 标识符 | 10.1007/s12665-025-12647-w |
| 摘要 | Dissolved organic matter (DOM) is a vital component of organic material in ecosystems. While DOM dynamics in general watersheds are well-studied, its composition and behavior in karst watersheds remain poorly constrained due to unique hydrogeological complexities. The focus of this study is on the Lianjiang River Basin, which is a typical karst watershed in southern China, and the objective of the study is to identify the sources of fatty acids, analyze the impact of river water-groundwater relationships on the distribution of fatty acids, and investigate the behavior of dissolved organic matter (DOM) in the karst water system. In this study, measurements of fatty acid and dissolved organic carbon (DOC) concentrations, hydrochemical indicators, and stable isotopic compositions (δD and δ18O) were taken for surface water and groundwater samples, including both shallow and deep groundwater. Additionally, microbial analysis was conducted on the groundwater samples to gain further insight into the microbial communities present in the karst water system. Fatty acid contents in river water, shallow groundwater, and deep groundwater were 15,595 ± 14,164 ng/L, 15,600 ± 10,089 ng/L, and 27,353 ± 20,378 ng/L, respectively. The study found that deep groundwater had the highest concentrations of fatty acids, while river water and shallow groundwater had similar fatty acid contents. The higher standard deviation of fatty acids in surface water and groundwater samples can be attributed to the unique characteristics of karst aquifers. Fatty acids in shallow groundwater mainly originate from three sources: surface soil-associated organic matter, fecal-associated sources, and pharmaceutical or cosmetic-associated sources. Hydrochemical and stable isotope compositions (δD and δ18O) showed river water were recharged by adjacent groundwater, which influenced the spatial distribution of fatty acids in the study area. The deep karst aquifer may serve as a DOM sink in the karst watershed, and the DOM in the karst water system was affected by natural and anthropogenic sources input as well as surface water-groundwater relationships during the dry season. |
