Experimentally simulated sea level rise destabilizes carbon-mineral associations in temperate tidal marsh soil

How sea level rise (SLR) alters carbon (C) dynamics in tidal salt marsh soils is unresolved. Changes in hydrodynamics could influence organo-mineral associations, influencing dissolved organic carbon (DOC) fluxes. As SLR increases the duration of inundation, we hypothesize that lateral DOC export wi...

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Bibliographic Details
Published in:Biogeochemistry 2023-03, Vol.163 (2), p.103-120
Main Authors: Fettrow, Sean, Vargas, Rodrigo, Seyfferth, Angelia L.
Format: Article
Language:English
Subjects:
Analytical methods
Biogeosciences
Carbon
Carbon dioxide
Carbon dioxide emissions
Climate change
Cores
Dissolution
Dissolved organic carbon
Dissolving
Dynamics
Earth and Environmental Science
Earth Sciences
Ecosystems
Emissions
Environmental Chemistry
Environmental Sciences & Ecology
Gases
Geology
Global warming
Greenhouse effect
greenhouse gas fluxes
Greenhouse gases
Hydrodynamics
Iron
lateral carbon fluxes
Life Sciences
Mesocosms
Neap tides
organo-mineral associations
Oxides
Pore water
Salt marshes
Saltmarshes
Sea level
Sea level changes
Sea level rise
Soil
Soil dynamics
Soil gases
Soil testing
Soil water
Soils
Solid phases
Spectroscopy
Stocks
synchrotron
Tidal marshes
Trace gases
vertical carbon fluxes
Water level fluctuations
Water levels
X ray absorption
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Summary:How sea level rise (SLR) alters carbon (C) dynamics in tidal salt marsh soils is unresolved. Changes in hydrodynamics could influence organo-mineral associations, influencing dissolved organic carbon (DOC) fluxes. As SLR increases the duration of inundation, we hypothesize that lateral DOC export will increase due to reductive dissolution of C-bearing iron (Fe) oxides, destabilizing soil C stocks and influencing greenhouse gas emissions. To test this, soil cores (0–8 cm depth) were collected from the high marsh of a temperate salt marsh that currently experiences changes in water level and soil redox oscillation due to spring-neap tides. Mesocosms experimentally simulated SLR by continuously inundating high marsh soils and were compared to mesocosms with Control conditions, where the water level oscillated on a spring-neap cycle. Porewater DOC, lateral DOC, and porewater reduced Fe (Fe 2+ ) concentrations were significantly higher in SLR treatments (1.7 ± 0.5 mM, 0.63 ± 0.14 mM, and 0.15 ± 0.11 mM, respectively) than Control treatments (1.2 ± 0.35 mM, 0.56 ± 0.15 mM, and 0.08 ± 01 mM, respectively Solid phase analysis with Fe extended X-ray absorption fine-structure spectroscopy further revealed that SLR led to > 3 times less Fe oxide-C coprecipitates than Control conditions In addition, the overall global warming potential (GWP) decreased under SLR due to suppressed CO 2 emissions. Our data suggest that SLR may increase lateral C export of current C stocks by dissolving C-bearing Fe oxides but decrease the overall GWP from emissions of soil trace gases. These findings have implications for understanding the fate of SOC dynamics under future SLR scenarios.
ISSN:0168-2563
1573-515X
DOI:10.1007/s10533-023-01024-z