| Title | 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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| Author | Loder, A L; Gillespie, A; Ardakani, O H ; Finkelstein, S A |
| Source | American Geophysical Union Fall Meeting 2021, abstracts; B53D-04, 2021 p. 1  Open Access |
| Links | Online - En ligne
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| Image |  |
| Year | 2021 |
| Alt Series | Natural Resources Canada, Contribution Series 20210432 |
| Publisher | American Geophysical Union |
| Meeting | American Geophysical Union Fall Meeting 2021; New Orleans, LA; US; December 13-17, 2021 |
| Document | Web site |
| Lang. | English |
| Media | digital; on-line |
| File format | html; pdf |
| Province | Ontario |
| NTS | 40G; 40J/02; 40J/03 |
| Area | Big Creek; Lake Erie |
| Lat/Long WENS | -83.5000 -82.5000 42.2500 41.7500 |
| Subjects | hydrogeology; geochemistry; environmental geology; soils science; Science and Technology; Nature and Environment; Holocene; surface waters; rivers; lakes; wetlands; watersheds; marshes; carbon
geochemistry; soil geochemistry; core samples; climate effects; paleoecology; radiometric dating; radiocarbon dating; organic carbon; pyrolysis; water levels; nitrogen; oxygen; Big Creek Watershed; Fresh water; Climate change; Hydrology; Phanerozoic;
Cenozoic; Quaternary |
| Program | Energy Geoscience Clean Energy Resources - Decreasing Environmental Risk |
| Released | 2021 12 01 |
| Abstract | 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. |
| Summary | (Plain Language Summary, not published)
This study investigates paleoecological analyses (radiometric dating, carbon densities, and rates of accumulation) and programmed pyrolysis for organic
matter characterization of a riverine-influenced reference marsh (CBC3-01) in the watershed of Big Creek which drains into Lake Erie in southern Ontario, Canada to better understand the capacity for freshwater marshes to be long-term carbon
sinks. |
| GEOSCAN ID | 329273 |
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