The glacial-terrestrial-fluvial pathway: A multiparametrical analysis of spatiotemporal dissolved organic matter variation in three catchments of Lake Nam Co, Tibetan Plateau

Maurischat, Philipp; Lehnert, Lukas; Zerres, Vinzenz H. D.; Tran, Tuong Vi; Kalbitz, Karsten; Rinnan, Asmund; Li, Xiao Gang; Dorji, Tsechoe und Guggenberger, Georg (2022): The glacial-terrestrial-fluvial pathway: A multiparametrical analysis of spatiotemporal dissolved organic matter variation in three catchments of Lake Nam Co, Tibetan Plateau. In: Science of the Total Environment, Bd. 838, 156542

Abstract

The Tibetan Plateau (TP) is a sensitive alpine environment of global importance, being Asia's water tower, featuring vast ice masses and comprising the world's largest alpine grasslands. Intensified land-use and pronounced global climate change have put pressure on the environment of the TP. We studied the tempo-spatial variability of dissolved organic matter (DOM) to better understand the fluxes of nutrients and energy from terrestrial to aquatic ecosystems in the TP. We used a multiparametrical approach, based on inorganic water chemistry, dissolved organic carbon (DOC) concentration, dissolved organic matter (DOM) characteristics (chromophoric DOM, fluorescence DOM and delta C-13 of DOM) in stream samples of three catchments of the Nam Co watershed and the lake itself. Satellite based plant cover estimates were used to link biogeochemical data to the structure and degradation of vegetation zones in the catchments. Catchment streams showed site-specific DOM signatures inherited fromglaciers, wetlands, groundwater, and Kobresia pygmaea pastures. By comparing streamand lake samples, we found DOM processing and unification by loss of chromophoric DOM-signatures and a change towards an autochthonous source of lake DOM. DOM-diversity was largest in the headwaters of the catchments and heavily modified in terminal aquatic systems. Seasonality was characterized by a minor influence of freshet and by a very strong impact of the Indian summermonsoon onDOMcomposition, with more microbial DOM sources. The DOM of Lake NamCo differed chemically fromstreamwater samples, indicating the lake to be a quasi-marine environment in regards to the degree of chemical modification and sources of DOM. DOM-proved to be a powerful marker to elucidate consequences of land use and climatic change on biogeochemical processes in High Asian alpine ecosystems.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Geowissenschaften > Department für Geographie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie
• ISSN: 0048-9697
• Sprache: Englisch
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 317513741