Vegetal Undercurrents—Obscured Riverine Dynamics of Plant Debris - Archive ouverte HAL Access content directly
Journal Articles Journal of Geophysical Research: Biogeosciences Year : 2022

Vegetal Undercurrents—Obscured Riverine Dynamics of Plant Debris

, , , (1) ,
1
Melissa S. Schwab
  • Function : Author
Robert G. Hilton
  • Function : Author
Negar Haghipour
  • Function : Author
Timothy Eglinton
  • Function : Author

Abstract

Much attention has been focused on fine-grained sediments carried as suspended load in rivers due to their potential to transport, disperse, and preserve organic carbon (OC), while the transfer and fate of OC associated with coarser-grained sediments in fluvial systems have been less extensively studied. Here, sedimentological, geochemical, and biomolecular characteristics of sediments from river depth profiles reveal distinct hydrodynamic behavior for different pools of OC within the Mackenzie River system. Higher radiocarbon (14C) contents, low N/OC ratios, and elevated plant-derived biomarker loadings suggest a systematic transport of submerged vascular plant debris above the active riverbed in large channels both upstream of and within the delta. Subzero temperatures hinder OC degradation promoting the accumulation and waterlogging of plant detritus within the watershed. Once entrained into a channel, sustained flow strength and buoyancy prevent plant debris from settling and keep it suspended in the water column above the riverbed. Helical flow motions within meandering river segments concentrate lithogenic and organic debris near the inner river bends forming a sediment-laden plume. Moving offshore, we observe a lack of discrete, particulate OC in continental shelf sediments, suggesting preferential trapping of coarse debris within deltaic and neritic environments. The delivery of waterlogged plant detritus transport and high sediment loads during the spring flood may reduce oxygen exposure times and microbial decomposition, leading to enhanced sequestration of biospheric OC. Undercurrents enriched in coarse, relatively fresh plant fragments appear to be reoccurring features, highlighting a poorly understood yet significant mechanism operating within the terrestrial carbon cycle.
Fichier principal
Vignette du fichier
JGR Biogeosciences - 2022 - Schwab - Vegetal Undercurrents Obscured Riverine Dynamics of Plant Debris.pdf (21.56 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

insu-03643029 , version 1 (20-04-2022)

Licence

Attribution - CC BY 4.0

Identifiers

Cite

Melissa S. Schwab, Robert G. Hilton, Negar Haghipour, J. Jotautas Baronas, Timothy Eglinton. Vegetal Undercurrents—Obscured Riverine Dynamics of Plant Debris. Journal of Geophysical Research: Biogeosciences, 2022, 127, ⟨10.1029/2021JG006726⟩. ⟨insu-03643029⟩
27 View
12 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More