The Marapanim River estuary (MRE) is part of the Amazon estuarine system located in northern Brazil, which is characterized as having extensive mangrove forests. Given that previous studies reported CO₂ and CH₄ fluxes from mangrove creeks in this region, here we investigate the potential organic carbon sequestration of the creek mudflats to get a better understanding of the carbon cycling through these systems. Sediment accumulation rates derived from ²¹⁰Pb dating indicated that sampled cores represent the previous 24 (± 4) yr. The approximately 24-year total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) burial rates were estimated to be 192.5 (± 43.5), 15.3 (± 4.1) and 3.2 (± 0.8) g m⁻² yr⁻¹, respectively. A binary source mixing model based on carbon stable isotopes (δ¹³C) revealed that the sedimentary organic matter (OM) is mainly influenced by marine phytoplankton input (49% to 95%). Furthermore, the TOC accumulation rates found here were slightly higher than the global averages estimated for within mangrove forests, suggesting that these unaccounted carbon sinks along creek mudflat environments are relevant for carbon budgets in mangrove-colonized coastal zones. The highest contents, stocks and accumulation rates were found in the tidal creek sediments that are most influenced by nearby mangroves and are more protected than sediments from major river margins. Our results indicate that the creek mudflats play a major role in carbon and nutrients sequestration, directly related to grain size and OM sources.

马拉帕尼姆河河口（MRE）是位于巴西北部的亚马逊河口系统的一部分，该河口系统的特征是拥有广阔的红树林。鉴于先前的研究报道了该地区红树林小溪中的CO ₂和CH ₄通量，因此我们在此研究了小溪泥滩中潜在的有机碳固存，以更好地了解通过这些系统的碳循环。从²¹⁰ Pb测年获得的沉积物积聚速率表明，取样岩心代表了之前的24（±4）年。大约24年的总有机碳（TOC），总氮（TN）和总磷（TP）埋葬率估计为192.5（±43.5），15.3（±4.1）和3.2（±0.8）gm - ² 年^-1， 分别。二进制源混合模型基于碳的稳定同位素（δ ¹³C）表明，沉积有机物（OM）主要受海洋浮游植物输入的影响（49％至95％）。此外，这里发现的TOC积累率略高于红树林内的全球平均估计值，这表明沿小河滩涂环境的这些未说明的碳汇与红树林殖民化沿海地区的碳预算有关。潮汐河沉积物中的含量，储量和积累率最高，这些沉积物受附近红树林的影响最大，并且比主要河流边缘的沉积物受到的保护更大。我们的结果表明，小河滩涂在碳和养分固存中起主要作用，与颗粒大小和OM来源直接相关。