Temporal deconvolution of vascular plant-derived fatty acids exported from terrestrial watersheds

Relatively little is known about the amount of time that lapses between the photosynthetic fixation of carbon by vascular land plants and its incorporation into the marine sedimentary record, yet the dynamics of terrestrial carbon sequestration have important implications for the carbon cycle. Vascu...

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Bibliographic Details
Published in:Geochimica et Cosmochimica Acta
Main Authors: Vonk, Jorien E., Drenzek, Nicholas J., Hughen, Konrad A., Stanley, Rachel H.R., McIntyre, Cameron, Montluçon, Daniel B., Giosan, Liviu, Southon, John R., Santos, Guaciara M., Druffel, Ellen R.M., Andersson, August A., Sköld, Martin, Eglinton, Timothy I.
Format: Article in Journal/Newspaper
Language:English
Published: 2019
Subjects:
Leaf waxes
Organic matter
Radiocarbon
Residence time
Sediment
Terrestrial carbon
/dk/atira/pure/sustainabledevelopmentgoals/life_below_water
name=SDG 14 - Life Below Water
Mackenzie Delta
permafrost
Online Access:https://research.vu.nl/en/publications/1030027a-bf30-45e9-a436-30b74019426c
https://doi.org/10.1016/j.gca.2018.09.034
https://hdl.handle.net/1871.1/1030027a-bf30-45e9-a436-30b74019426c
https://research.vu.nl/ws/files/235238041/Temporal_deconvolution_of_vascular_plant_derived_fatty_acids_exported_from_terrestrial_watersheds.pdf
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Summary:Relatively little is known about the amount of time that lapses between the photosynthetic fixation of carbon by vascular land plants and its incorporation into the marine sedimentary record, yet the dynamics of terrestrial carbon sequestration have important implications for the carbon cycle. Vascular plant carbon may encounter multiple potential intermediate storage pools and transport trajectories, and the age of vascular plant carbon accumulating in marine sediments will reflect these different pre-depositional histories. Here, we examine down-core 14 C profiles of higher plant leaf wax-derived fatty acids isolated from high fidelity sedimentary sequences spanning the so-called “bomb-spike” and encompassing a ca. 60-degree latitudinal gradient from tropical (Cariaco Basin), temperate (Saanich Inlet), and polar (Mackenzie Delta) watersheds to constrain integrated vascular plant carbon storage/transport times (“residence times”). Using a modeling framework, we find that, in addition to a “young” (conditionally defined as < 50 y) carbon pool, an old pool of compounds comprises 49 to 78 % of the fractional contribution of organic carbon (OC) and exhibits variable ages reflective of the environmental setting. For the Mackenzie Delta sediments, we find a mean age of the old pool of 28 ky (±9.4, standard deviation), indicating extensive pre-aging in permafrost soils, whereas the old pools in Saanich Inlet and Cariaco Basin sediments are younger, 7.9 (±5.0) and 2.4 (±0.50) to 3.2 (±0.54) ky, respectively, indicating less protracted storage in terrestrial reservoirs. The “young” pool showed clear annual contributions for Saanich Inlet and Mackenzie Delta sediments (comprising 24% and 16% of this pool, respectively), likely reflecting episodic transport of OC from steep hillside slopes surrounding Saanich Inlet and annual spring flood deposition in the Mackenzie Delta, respectively. Contributions of 5–10 year old OC to the Cariaco Basin show a short delay of OC inflow, potentially related to transport time to the ...

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