Radiocarbon Constraints On Carbon Dynamics In River Basins

• Main Author: Schwab, Melissa Sophia
• Other Authors: Eglinton, Timothy I., Hilton, Robert G., Lupker, Maarten, Goñi, Miguel A.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: ETH Zurich 2020
• Subjects: Organic carbon cycling; Radiocarbon; Fluvial systems; Plant-derived biomarker; Permafrost; info:eu-repo/classification/ddc/550; Earth sciences; Arctic; permafrost
• Online Access: https://hdl.handle.net/20.500.11850/473295; https://doi.org/10.3929/ethz-b-000473295

Constraining inputs and processes that influence organic carbon (OC) storage and export in fluvial systems is crucial for understanding the fate of carbon during its transfer from the terrestrial biosphere to the marine sedimentary sink. However, given the heterogeneous and dynamic nature of carbon, in-depth knowledge of spatial and temporal scales over which carbon cycles through river systems is required. Pathways and timescales of carbon turnover and transport are known to vary with environmental conditions (temperature, humidity, topography etc.; e.g., Carvalhais et al., 2014; Galy et al., 2015) and are sensitive to anthropogenic disturbances (e.g., Butman et al., 2015; Grill et al., 2019; Raymond et al., 2008; Regnier et al., 2013). However, the relative importance of these factors for different types of fluvial systems remains the subject of debate (e.g., Marwick et al., 2015) and much work needs to be done to develop a comprehensive understanding of underlying processes and robust predictive capabilities regarding the nature, magnitude, and pace of future carbon cycle change. Acquisition of information on carbon cycle processes over appropriate spatial and temporal scales is crucial to quantitatively assess and upscale observations from watershed to regional and global biogeochemical scales. This thesis aims to further our understanding of controls impacting riverine OC export over various spatial and temporal scales under differing climatic and geomorphic settings. Sedimentological and organic geochemical tools are applied to a multi-annual time-series, located in a moderately steep, subalpine Swiss river basin, to assess the influence of short-term hydrological and environmental variability (seasonality, storm events) on exported carbon and plant-derived biomarkers (chapters 2 and 3). By augmenting pre-existing data with a comprehensive suite of new sedimentological and OC measurements, we constrain the inputs and propagation of particulate (POC) and dissolved (DOC) organic carbon in the Arctic ...