Lebrasse Marie Cindy, Schaeffer Blake A, Bohnenstiehl DelWayne R, Osburn Christopher L, Coffer Megan M, He Ruoying, Whitman Peter J, Salls Wilson B, Graybill David D
Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC, USA.
U.S. Environmental Protection Agency, Office of Research and Development, USA.
Estuar Coast Shelf Sci. 2025 Sep 15;322:109361. doi: 10.1016/j.ecss.2025.109361.
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 observations. This study used a linear model to correlate DOC and chromophoric dissolved organic matter (CDOM) absorption coefficient at 440 nm ( ; ) 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 d was greater than the average daily DOC export of 9.4 ± 8.3 g C m d 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.
溶解有机碳（DOC）的横向输运在潮汐沼泽碳收支中至关重要，但由于陆地 - 水生界面的动态性质和观测的局限性，估算DOC仍然是一项挑战。本研究使用线性模型将美国北卡罗来纳州秃头溪的DOC与440 nm处的发色溶解有机物（CDOM）吸收系数（ ； ）相关联。将模拟的DOC浓度与从半隐式跨尺度水文科学综合系统模型（SCHISM）得出的流速合并，以估算2021年1月至4月的每日DOC通量，代表北半球中纬度地区的冬季和春季。DOC通量取决于季节和潮汐，负值表示DOC输入到沼泽，正值表示输出到河口。结果表明，在降雨峰值后的2月和3月，DOC从沼泽输出。虽然潮汐淹没和降水增加的河流流量影响了DOC通量，但在研究期间，每日平均DOC输入量为 -13.6 ± 6.0 g C m² d，大于每日平均DOC输出量9.4 ± 8.3 g C m² d，这表明在早春期间，沼泽是DOC的净汇。本研究表明，使用SCHISM等模型进行的实地测量提供了DOC通量的全景图，其中降雨引发的河流流量影响DOC的迁移和向秃头溪等沿海系统的输出。
