Preprints
https://doi.org/10.5194/egusphere-2022-705
https://doi.org/10.5194/egusphere-2022-705
01 Aug 2022
 | 01 Aug 2022

Environmental and hydrologic controls on sediment and organic carbon export from a subalpine catchment: insights from a time-series

Melissa Sophia Schwab, Hannah Gies, Chantal Valérie Freymond, Maarten Lupker, Negar Haghipour, and Timothy Ian Eglinton

Abstract. Studies engaging in tracking headwater carbon signatures downstream remain sparse, despite their importance for constraining transfer and transformation pathways of organic carbon (OC) and developing regional-scale perspectives on mechanisms influencing the balance between remineralization and carbon export. Based on a 40-month time series, we investigate the dependence of hydrology and seasonality on the discharge of sediment and OC in a small Swiss subalpine watershed (Sihl River basin). We analyze concentrations and isotopic compositions (δ13C, F14C) of particulate OC and use dual-isotope mixing and machine learning frameworks to characterize and estimate source contributions, transport pathways, and export fluxes. The majority of transferred OC is sourced from plant biomass and soil material. Relative proportions of soil-derived particulate OC peak during the summer months, coinciding with maximum soil erosion rates. Bedrock-derived (petrogenic) OC abundant in headwater streams progressively decreases downstream in response to a lack of source material and efficient overprinting with biospheric organic matter, illustrating rapid OC transformation over short distances. Large variations in isotopic compositions observed during baseflow conditions converge and form a homogenous mixture enriched in OC and characterized by higher POC- F14C values following precipitation-driven events. We propose that storms facilitate surface runoff and shallow landsliding, resulting in the entrainment of fresh litter and surficial soil layers. Model results further indicate diverging mobilization pathways. Discharge and water stage describe the export of suspended sediment, while the prediction of POC fluxes is mostly supported by water stage and 1-day antecedent precipitation. Although particle transport in the Sihl River basin is mainly driven by hydrology, subtle changes in bedrock erosivity, slope angle, and floodplain extent likely have profound effects on the POC composition, age, and export yields.

Journal article(s) based on this preprint

13 Dec 2022
Environmental and hydrologic controls on sediment and organic carbon export from a subalpine catchment: insights from a time series
Melissa Sophia Schwab, Hannah Gies, Chantal Valérie Freymond, Maarten Lupker, Negar Haghipour, and Timothy Ian Eglinton
Biogeosciences, 19, 5591–5616, https://doi.org/10.5194/bg-19-5591-2022,https://doi.org/10.5194/bg-19-5591-2022, 2022
Short summary

Melissa Sophia Schwab et al.

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-705', Anonymous Referee #1, 22 Aug 2022
    • AC2: 'Reply on RC1', Melissa Schwab, 03 Oct 2022
  • RC2: 'Review of “Environmental and hydrologic controls on sediment and organic carbon export from a subalpine catchment: insights from a time-series” by Melissa Schwab and co-authors', Anonymous Referee #2, 30 Aug 2022
    • AC1: 'Reply on RC2', Melissa Schwab, 03 Oct 2022

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-705', Anonymous Referee #1, 22 Aug 2022
    • AC2: 'Reply on RC1', Melissa Schwab, 03 Oct 2022
  • RC2: 'Review of “Environmental and hydrologic controls on sediment and organic carbon export from a subalpine catchment: insights from a time-series” by Melissa Schwab and co-authors', Anonymous Referee #2, 30 Aug 2022
    • AC1: 'Reply on RC2', Melissa Schwab, 03 Oct 2022

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Publish subject to minor revisions (review by editor) (04 Oct 2022) by Sebastian Naeher
AR by Melissa Schwab on behalf of the Authors (01 Nov 2022)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (02 Nov 2022) by Sebastian Naeher
AR by Melissa Schwab on behalf of the Authors (12 Nov 2022)  Author's response   Manuscript 

Journal article(s) based on this preprint

13 Dec 2022
Environmental and hydrologic controls on sediment and organic carbon export from a subalpine catchment: insights from a time series
Melissa Sophia Schwab, Hannah Gies, Chantal Valérie Freymond, Maarten Lupker, Negar Haghipour, and Timothy Ian Eglinton
Biogeosciences, 19, 5591–5616, https://doi.org/10.5194/bg-19-5591-2022,https://doi.org/10.5194/bg-19-5591-2022, 2022
Short summary

Melissa Sophia Schwab et al.

Melissa Sophia Schwab et al.

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Short summary
The majority of river studies focuses on headwater or floodplain systems, while often neglecting intermediate river segments. Our study on the subalpine Sihl River bridges the gap between streams and lowlands and demonstrates that moderately steep river segments are areas of significant instream transformation, modulating the export of organic carbon over short distances.