Abstract Quantitative estimates of the flux, transportation, and burial of riverine particulate organic carbon (POC) in estuaries and shelf areas are crucial for understanding the carbon cycle in marginal seas. The complexity of the hydrodynamic environment and estuarine processes in the Changjiang River estuary (CRE) results in a POC flux with high spatiotemporal variability. In this study, we proposed a new method for time series monitoring of riverine POC flux by combining satellite ocean color and numerical modeling data. We used 500-m resolution geostationary satellite data from the Geostationary Ocean Color Imager (GOCI) to retrieve surface POC concentrations in the CRE and used the numerical Finite Volume Community Ocean Model (FVCOM) to simulate three-dimensional (3D) current and sediment distribution. Diurnal, seasonal, and annual variations in POC flux through the lower reaches (Datong Hydrological Station), upper estuary (Xuliujing Hydrological Station), and outlets of the CRE, as well as transportation and deposition outside the CRE, were examined from July 2011 to June 2018. The annual mean POC fluxes through the Datong, Xuliujing, and outlet sections were 1.16 ± 0.16 Tg C/yr, 1.29 ± 0.11 Tg C/yr, and 1.17 ± 0.11 Tg C/yr, respectively. After passing through the estuary, 35.2% of POC was deposited in the sandbar outside the outlets, 52.9% was transported to the south, and a small amount entered the eastern shelf. Thus, these results indicated that POC flux through the river and estuary sections differed from the effective riverine POC flux into the sea. The proposed method combining high spatiotemporal-resolution satellite data and numerical modeling not only makes full use of their advantages, but also reduces the uncertainty of their individual estimates. This approach also supports long-term monitoring of riverine fluxes to the sea and helps clarify the effects of terrestrial inputs on marginal seas under multiple stresses from human activities and climate change.

中文翻译：

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使用卫星数据和数值模拟估算高动态河口中的颗粒有机碳通量

摘要 对河口和陆架区河流颗粒有机碳 (POC) 的通量、运输和埋藏的定量估计对于了解边缘海的碳循环至关重要。长江口 (CRE) 水动力环境和河口过程的复杂性导致 POC 通量具有高时空变异性。在这项研究中，我们提出了一种结合卫星海洋颜色和数值建模数据的河流 POC 通量时间序列监测的新方法。我们使用来自地球同步海洋彩色成像仪 (GOCI) 的 500 米分辨率地球同步卫星数据来检索 CRE 中的表面 POC 浓度，并使用数值有限体积社区海洋模型 (FVCOM) 来模拟三维 (3D) 电流和沉积物分布. 昼夜、季节性、研究了 2011 年 7 月至 2018 年 6 月通过 CRE 下游（大同水文站）、上游（徐流泾水文站）和 CRE 出口以及 CRE 外的运输和沉积的 POC 通量和年度变化。通过大同、徐六井和出口断面的年平均 POC 通量分别为 1.16 ± 0.16 Tg C/yr、1.29 ± 0.11 Tg C/yr 和 1.17 ± 0.11 Tg C/yr。过河口后，35.2%的POC沉积在出海口外的沙洲，52.9%向南输送，少量进入东部陆架。因此，这些结果表明，通过河流和河口部分的 POC 通量不同于入海的有效河流 POC 通量。所提出的结合高时空分辨率卫星数据和数值建模的方法不仅充分利用了它们的优点，而且降低了它们个体估计的不确定性。这种方法还支持对河流入海通量的长期监测，并有助于阐明在人类活动和气候变化的多重压力下陆地输入对边缘海洋的影响。