Winter-Spring dynamics of dissolved organic carbon fluxes driven by precipitation in a North Carolina tidal marsh
Citation:
Lebrasse, M., B. Schaeffer, D. Bohnenstiehl, C. Osburn, M. Coffer, R. He, P. Whitman, W. Salls, AND D. Graybill. Winter-Spring dynamics of dissolved organic carbon fluxes driven by precipitation in a North Carolina tidal marsh. ESTUARINE, COASTAL AND SHELF SCIENCE. Elsevier Science Ltd, New York, NY, 322:109361, (2025). https://doi.org/10.1016/j.ecss.2025.109361
Impact/Purpose:
Tidal marshes only cover a small area worldwide but they have this incredible ability to capture carbon from the atmosphere, process it and store it for thousands of years in their soils. Since tidal marshes are influence by the ebb and flow of tides, the stored carbon seeps into the tidal waters (similar to brewing tea) and gets transported to adjacent ecosystems. The transport of this dissolved carbon has been increasingly recognized as an important component of carbon budgets in tidal marshes. However, estimates of this dissolved carbon are highly variable because tidal marshes are very small and dynamic systems, which makes it difficult to observe and measure this dissolved carbon. Without accurate estimates, it is difficult to quantify how much carbon is stored in these systems and how much of this carbon is being released back to the atmosphere, contributing to greenhouse gas emissions and climate change. Therefore, we need new approaches to measure this dissolved carbon and provide more accurate estimates. With the advantages that satellite remote sensing offers, this study combined satellite data with a model that simulates the circulation of water in the tidal marsh to estimate carbon fluxes from a tidal creek (Bald Head Creek) draining a small tidal marsh in southeastern North Carolina, USA. Results demonstrated that our approach provided estimates of carbon fluxes in tidal marshes like Bald Head Creek tidal wetlands within the range observed in other tidal marshes but also larger than similar-sized tidal marshes. More importantly, these results imply that despite their small size, the extensive and productive marshes surrounding tidal creeks like Bald Head Creek are significant sources of carbon to coastal waters and play a central role in global carbon budgets.
Description:
The lateral transport of dissolved organic carbon (DOC) is crucial in tidal marsh carbon budgets, but estimating DOC remains a challenge due to the dynamic nature of terrestrial-aquatic interfaces and limitations of in situ observations. This study used a linear model to correlate DOC and chromophoric dissolved organic matter (CDOM) absorption coefficient at 440 nm (aCDOM(440); r2 = 0.75) in Bald Head Creek, North Carolina, USA. Modeled DOC concentrations were merged with current velocity derived from the Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM) to estimate daily DOC fluxes from January to April 2021, representing winter and spring in the mid-latitude northern hemisphere. DOC flux depended on season and tide, where negative values represent DOC import into the marsh and positive values represent export to the estuary. Results showed that DOC was exported from the marsh in February and March after peak rainfall. While tidal inundation and increased river flow from precipitation influenced DOC flux, the average daily DOC import of −13.6 ± 6.0 g C m−2 d−1 was greater than the average daily DOC export of 9.4 ± 8.3 g C m−2 d−1 during the study period, showing that the marsh was a net sink for DOC during the early spring. This study demonstrated that field measurements with models like SCHISM provided a synoptic representation of DOC flux, where rainfall-induced river discharge impacts DOC mobilization and export to coastal systems like Bald Head Creek.
URLs/Downloads:
DOI: Winter-Spring dynamics of dissolved organic carbon fluxes driven by precipitation in a North Carolina tidal marsh