Increasing rates of carbon burial in southwest Florida coastal wetlands

Journal of Geophysical Research: Biogeosciences
By: , and 

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Abstract

Rates of organic carbon (OC) burial in some coastal wetlands appear to be greater in recent years than they were in the past. Possible explanations include ongoing mineralization of older OC or the influence of an unaccounted‐for artefact of the methods used to measure burial rates. Alternatively, the trend may represent real acceleration in OC burial. We quantified OC burial rates of mangrove and coastal freshwater marshes in southwest Florida through a comparison of rates derived from 210Pb, 137Cs, and surface marker horizons (MHs). Age/depth profiles of lignin: OC were used to assess whether down‐core remineralization had depleted the OC pool relative to lignin, and lignin phenols were used to quantify the variability of lignin degradation. Over the past 120 years, OC burial rates at seven sites increased by factors ranging from 1.4 to 6.2. We propose that these increases represent net acceleration. Change in relative sea‐level rise is the most likely large‐scale driver of acceleration, and sediment deposition from large storms can contribute to periodic increases. Mangrove sites had higher OC and lignin burial rates than marsh sites, indicating inherent differences in OC burial factors between the two habitat types. The higher OC burial rates in mangrove soils mean that their encroachment into coastal freshwater marshes has the potential to increase burial rates in those locations even more than might be expected from the acceleration trends. Regionally, these findings suggest that burial represents a substantially growing proportion of the coastal wetland carbon budget.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Increasing rates of carbon burial in southwest Florida coastal wetlands
Series title Journal of Geophysical Research: Biogeosciences
DOI 10.1029/2019JG005349
Volume 125
Issue 2
Year Published 2020
Language English
Publisher American Geophysical Union
Contributing office(s) Wetland and Aquatic Research Center
Description e2019JG005349, 25 p.
Country United States
State Florida
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