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Abstract The fluxes of dissolved organic carbon (DOC) through tidal marsh‐influenced estuaries remain poorly quantified and have been identified as a missing component in carbon‐cycle models. The extreme variability inherent to these ecosystems of the land‐ocean interface challenge our ability to capture DOC‐concentration dynamics and to calculate accurate DOC fluxes. In situ discrete and continuous measurements provide high‐quality estimates of DOC concentration, but these strategies are constrained spatially and temporally and can be costly to operate. Here, field measurements and high‐spatial‐resolution remote sensing were used to train and validate a predictive model of DOC‐concentration distributions in the Plum Island Estuary (PIE), a mesotidal saltmarsh‐influenced estuary in Massachusetts. A large set of field measurements collected between 2017 and 2023 was used to develop and validate an empirical algorithm to retrieve DOC concentration with a ±15% uncertainty from Sentinel‐2 imagery. Implementation on 141 useable images produced a 6‐year time series (2017–2023) of DOC distributions along the thalweg. Analysis of the time series helped identify river discharge, tidal water level (WL), and a marsh enhanced vegetation index 2 as predictors of DOC distribution in the estuary, and facilitated the training and validation of a simple model estimating the distribution. This simple model was able to predict DOC along the PIE thalweg within ±16% of the in situ measurements. Implementation for three years (2020–2022) illustrated how this type of remote‐sensing‐informed models can be coupled with the outputs hydrodynamic models to calculate DOC fluxes in tidal marsh‐influenced estuaries and estimate DOC export to the coastal ocean.
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This content will become publicly available on January 1, 2026
Comparative Metabolism and Blue Carbon Sequestration of Two Wetland-Dominated Estuaries
Coastal tidal wetlands and estuaries play important roles in the global carbon budget by contributing to the net withdrawal of CO2from the atmosphere. We quantified the linkages between terrestrial and oceanic systems, marsh-to-bay carbon exchange, and the uptake of CO2from the atmosphere in the wetland-dominated Plum Island Sound (MA, USA) and Duplin River (GA, USA) estuaries. The C budgets revealed that autotrophic marshes [primary production:ecosystem respiration (P:R) ~1.3:1] are tightly coupled to heterotrophic aquatic systems (P:R ~0.6:1). Levels of marsh gross primary production are similar in these systems (865 ± 39 and 768 ± 74 gC m−2year−1in Plum Island and the Duplin, respectively) even though they are in different biogeographic provinces. In contrast to inputs from rivers and coastal oceans, tidal marshes are the dominant source of allochthonous matter that supports heterotrophy in aquatic systems. Dissolved inorganic carbon (DIC) exported from marshes to the coastal ocean was a major flux pathway in the Duplin River; however, there was no evidence of DIC export from Plum Island marshes and only minor export to the ocean. Burial was a sink for 53% of marsh net ecosystem production (NEP) on Plum Island, but only 19% of marsh NEP in the Duplin. Burial was the dominant blue carbon sequestration pathway at Plum Island, whereas in the Duplin, DIC and organic carbon export to the ocean were equally important. Regional- and continental-scale C budgets should better reflect wetland-dominated systems to more accurately characterize their contribution to global CO2sequestration.
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- Award ID(s):
- 2224608
- PAR ID:
- 10600909
- Publisher / Repository:
- Ocean-Land-Atmosphere Research
- Date Published:
- Journal Name:
- Ocean-Land-Atmosphere Research
- Volume:
- 4
- ISSN:
- 2771-0378
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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