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

  • Sean Fettrow
  • , Rodrigo Vargas
  • , Angelia L. Seyfferth

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

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 (Fe2+) 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 CO2 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.

Original languageEnglish
Pages (from-to)103-120
Number of pages18
JournalBiogeochemistry
Volume163
Issue number2
DOIs
StatePublished - Mar 2023
Externally publishedYes

Funding

We thank Chloe Kroll for sampling assistance, UD Soil Testing Laboratory for analytical assistance, Bruce Ravell for beamline assistance, Laurel Thomas Arrigo for the use of a ferrihydrite-galacturonic acid coprecipitate standard for Fe EXAFS, and the staff of the Delaware National Estuarine Research Reserve (DNERR). A.L.S. acknowledges support from the National Science Foundation Grants #1759879 and #2012484, S.F. acknowledges support from the Delaware Environmental Institute, and R.V. acknowledges support from the National Science Foundation grant #1652594 and U.S. Department of Energy (DOE) grant #DE-SC0023099 and #DE-SC0022185. Parts of this research used the BMM (6-BM) Beamline of the National Synchrotron Radiation Lightsource II, an Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. The authors acknowledge the land on which they conducted this study is the traditional home of the Lenni-Lenape tribal nation (Delaware nation). A.L.S. acknowledges support from the National Science Foundation Grants #1759879 and #2012484, S.F. acknowledges support from the Delaware Environmental Institute, and R.V. acknowledges support from the National Science Foundation grant #1652594 and U.S. Department of Energy (DOE) Grants #DE-SC0023099 and #DE-SC0022185.

Keywords

  • Dissolved organic carbon
  • Greenhouse gas fluxes
  • Lateral carbon fluxes
  • Organo-mineral associations
  • Synchrotron
  • Vertical carbon fluxes

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