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publications > paper > sediment accretion and organic carbon burial relative to sea-level rise and storm events in two mangrove forests in Everglades National Park

Sediment accretion and organic carbon burial relative to sea-level rise and storm events in two mangrove forests in Everglades National Park

Joseph M. Smoak a,*, Joshua L. Breithaupt a, Thomas J. Smith III b, Christian J. Sanders c

a University of South Florida, Environmental Science, Policy and Geography, St. Petersburg, FL, USA
b U.S. Geological Survey, Southeast Ecological Science Center, St. Petersburg, FL, USA
c Universidade Federal de Fluminense (UFF), Departamento de Geoquímica, Niterói, RJ, Brazil

* Corresponding author. E-mail address: (J.M. Smoak).

NOTICE: this is the author's version of a work that was accepted for publication in Catena. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Catena, Volume 104, May 2013, DOI: 10.1016/j.catena.2012.10.009. Posted here with permission from Elsevier.


> Abstract

The goal of this investigation was to examine how sediment accretion and organic carbon (OC) burial rates in mangrove forests respond to climate change. Specifically, will the accretion rates keep pace with sea-level rise, and what is the source and fate of OC in the system? Mass accumulation, accretion and OC burial rates were determined via 210Pb dating (i.e. 100 year time scale) on sediment cores collected from two mangrove forest sites within Everglades National Park, Florida (USA). Enhanced mass accumulation, accretion and OC burial rates were found in an upper layer that corresponded to a well-documented storm surge deposit. Accretion rates were 5.9 and 6.5 mm yr-1 within the storm deposit compared to overall rates of 2.5 and 3.6 mm yr-1. These rates were found to be matching or exceeding average sea-level rise reported for Key West, Florida. Organic carbon burial rates were 260 and 393 g m-2 yr-1 within the storm deposit compared to 151 and 168 g m-2 yr-1 overall burial rates. The overall rates are similar to global estimates for OC burial in marine wetlands. With tropical storms being a frequent occurrence in this region the resulting storm surge deposits are an important mechanism for maintaining both overall accretion and OC burial rates. Enhanced OC burial rates within the storm deposit could be due to an increase in productivity created from higher concentrations of phosphorus within storm-delivered sediments and/or from the deposition of allochthonous OC. Climate change-amplified storms and sea-level rise could damage mangrove forests, exposing previously buried OC to oxidation and contribute to increasing atmospheric CO2 concentrations. However, the processes described here provide a mechanism whereby oxidation of OC would be limited and the overall OC reservoir maintained within the mangrove forest sediments.

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Related information:

SOFIA Project: Dynamics of Land Margin Ecosystems: Historical Change, Hydrology, Vegetation, Sediment, and Climate

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