| Titre | Drivers of high rates of carbon accumulation during the Middle and Late Holocene in a riverine-influenced freshwater marsh in a Lake Erie watershed |
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| Auteur | Loder, A L; Gillespie, A; Ardakani, O H ; Finkelstein, S A |
| Source | American Geophysical Union Fall Meeting 2021, abstracts; B53D-04, 2021 p. 1  Accès ouvert |
| Liens | Online - En ligne
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| Image |  |
| Année | 2021 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20210432 |
| Éditeur | American Geophysical Union |
| Réunion | American Geophysical Union Fall Meeting 2021; New Orleans, LA; US; décembre 13-17, 2021 |
| Document | site Web |
| Lang. | anglais |
| Media | numérique; en ligne |
| Formats | html; pdf |
| Province | Ontario |
| SNRC | 40G; 40J/02; 40J/03 |
| Région | Grand Crique; Lac Érié |
| Lat/Long OENS | -83.5000 -82.5000 42.2500 41.7500 |
| Sujets | Holocène; eaux de surface; rivières; lacs; terres humides; bassins versants; marais; géochimie du carbone; géochimie du sol; échantillons carrotés; effets climatiques; paléoécologie; datation
radiométrique; datation au radiocarbone; carbone organique; pyrolyse; niveaux d'eau; azote; oxygène; Eau douce; Changement climatique; Hydrologie; hydrogéologie; géochimie; géologie de l'environnement; pédologie; Sciences et technologie; Nature et
environnement; Phanérozoïque; Cénozoïque; Quaternaire |
| Programme | Les géosciences de l'énergie Ressources d'énergie propre - réduire les risques environnementaux |
| Diffusé | 2021 12 01 |
| Résumé | (disponible en anglais seulement)
Freshwater marshes are one of the most prevalent wetland types in North America, have potential to accumulate carbon (C) at high rates over short (decades,
post-European settlement) and long (centuries and millennia, pre-European settlement) timescales, and bury C in deeper soils. However, analyses on long soil cores that extend back to the Middle and Late Holocene are scarce yet needed to improve
existing estimates for rates of burial of organic and inorganic C fractions to understand how known hydro-climatic changes have affected long-term apparent rates of C accumulation pre- and post-European settlement.
For this study, we collected a
4-m core from a riverine-influenced reference marsh (CBC3-01) in the watershed of Big Creek which drains into Lake Erie in southern Ontario, Canada. Using this long core, we conducted paleoecological analyses (radiometric dating, C densities, rates
of C accumulation) and programmed pyrolysis for organic matter characterization to better understand the capacity for freshwater marshes to be long-term C sinks.
Rates of total C accumulation in CBC3-01 were on average (± standard deviation) 59 ±
71 g C m-2 yr-1 since formation 5,710 cal. year BP, and highest upon the Nipissing Phases I and II (sharp rises of water levels in the lower Great Lakes) and during the post-European settlement period. These rates are comprised of both organic and
inorganic C fractions ranging between 3-212 g C m-2 yr-1 and 0.4-119 g C m-2 yr-1, respectively, and influenced by rates of marsh sediment accretion ranging between 0.02-0.67 cm yr-1. Hydrogen and oxygen indices from the programmed pyrolysis suggest
high variability in organic provenance throughout the Holocene. Ratios of total organic carbon and total nitrogen contents (TOC/TN) were highest (primarily above 15 with some higher than 20) from the time of wetland formation until 4,900 cal. yr BP.
These values have fluctuated between 6.5-14.1 since 3,940 cal. yr BP demonstrating the deposition of predominantly autochthonous organics in the late Holocene. Our work builds upon increasing recognition of the significance of soil depths and C
stocks in freshwater marshes which are underrepresented and underreported in regional and national soil C stock inventories. In this presentation, we show how hydro-climatic events and human activities have increased rates of C burial, and the
importance of considering organic versus inorganic and autochthonous versus allochthonous C fractions in marsh C budgets in order to accurately understand the potential for freshwater marshes to be net C sinks. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Cette étude examine les analyses paléoécologiques (datation radiométrique, densités de carbone et taux d'accumulation) et la pyrolyse programmée
pour la caractérisation de la matière organique d'un marais de référence influencé par la rivière (CBC3-01) dans le bassin versant de Big Creek qui se déverse dans le lac Érié dans le sud de l'Ontario, au Canada, afin de mieux comprendre la capacité
des marais d'eau douce à être des puits de carbone à long terme. |
| GEOSCAN ID | 329273 |
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