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Soil organic carbon development and turnover in natural and disturbed salt marsh environments

December 11, 2020

Salt marsh survival with sea‐level rise (SLR) increasingly relies on soil organic carbon (SOC) accumulation and preservation. Using a novel combination of geochemical approaches, we characterized fine SOC (≤1 mm) supporting marsh elevation maintenance. Overlaying thermal reactivity, source (δ13C), and age (F14C) information demonstrates several processes contributing to soil development: marsh grass production, redeposition of eroded material, and microbial reworking. Redeposition of old carbon, likely from creekbanks, represented ∼9‐17% of shallow SOC (≤26 cm), indicating that this process may become increasingly important with SLR. Soils stored marsh grass‐derived compounds with a range of reactivities that were reworked over centuries‐to‐millennia. Decomposition decreases SOC thermal reactivity throughout the soil column while the decades‐long disturbance of ponding accelerated this shift in surface horizons. Empirically derived estimates of SOC turnover based on geochemical composition spanned a wide range (640–9,951 years) and have the potential to inform future predictions of marsh ecosystem evolution.

Publication Year 2020
Title Soil organic carbon development and turnover in natural and disturbed salt marsh environments
DOI 10.1029/2020GL090287
Authors Sheron Luk, Katherine Todd-Brown, Meagan J. Eagle, Ann McNichol, Jonathan Sanderman, Kelsey Gosselin, Amanda C. Spivak
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Index ID 70217214
Record Source USGS Publications Warehouse
USGS Organization Woods Hole Coastal and Marine Science Center