河口在近海碳循环研究中的作用已成为全球变化研究的热点与难点。本研究选择黄河口、辽河口为研究对象，系统分析了表层沉积物有机碳（TOC）和无机碳（TIC）空间分布特征，结合粒度、总氮（TN）及碳稳定同位素，探讨了TOC与TIC沉积的相互关系，采用端元混合模型定量区分了内外源对沉积物碳的贡献，揭示了中国北方典型河口沉积物碳空间差异的驱动机制。主要研究结果如下： （1）黄河口TIC含量（6.3 - 20.1 g kg-1）明显高于TOC（0.2 - 4.4 g kg-1），而辽河口TIC含量（0.4 - 4.2 g kg-1）却低于TOC（0.1 - 8.7 g kg-1）。TOC和TIC在黄河口北部区域明显高于南部区域，而在辽河口表现为中部低于东西两侧区域，整体上深水区含量高于浅水区。 （2）黄河口表层沉积物C:N和δ13Corg（2.1 - 10.1，-24.26‰ ~ -22.66‰）比辽河口（0.8 - 13.4，-27.80‰ ~ -22.12‰）变幅小；黄河口北部及东部TOC主要是海源贡献，但在南部海湾区陆源贡献却高达75%，而辽河口近岸区TOC陆源组分明显高于离岸区，两河口深水区均以海源贡献为主。 （3）黄河口和辽河口沉积物碳空间分布均受河口水动力环境影响，水体强烈的再悬浮作用导致水体/沉积物中有机碳分解，而高值TIC除了受水体生物作用影响之外，还与POC/TOC的分解有关，而后者起主要作用。 总体而言，中国北方河口沉积物碳含量及空间分布差异与河口生产力、入海河流混合行为、局部水动力条件、水体再悬浮等综合作用有关。

Studying the carbon dynamics of estuarine sediment is crucial to understanding of carbon cycle in the coastal ocean. This study is designed to investigate the spatial variability of organic (TOC) and inorganic carbon (TIC), and to explore the mechanisms regulating their dynamics in surface sediment of the Yellow River Estuary (YRE) and Liao River Estuary (LRE). The main findings are listed as follows. (1) TIC (6.3-20.1 g kg-1) was much higher than TOC (0.2-4.4 g kg-1) in the YRE, but TIC (0.4 - 4.2 g kg-1) much lower than TOC (0.1 - 8.7 g kg-1) in the LRE. Both TOC and TIC were generally higher to the north than to the south in the YRE, and higher offshore than nearshore in the LRE, primarily due to the differences in kinetic energy level (i.e., higher to the south and nearshore). (2) The ranges of C:N and δ13Corg were smaller in the YRE (2.1 - 10.1 and -24.26‰ ~ -22.66‰) than in the LRE (0.8 - 13.4 and -27.80‰ ~ -22.12‰). Our analysis suggested that TOC was mainly from marine sources in the YER, except in the southern shallow bay where approximately 75% of TOC was terrigenous. The contribution of terrestrial sources TOC was much higher in the nearshore area than in the offshore area in the LRE. (3) The overall low levels of TOC were due to profound resuspension that could cause enhanced decomposition. On the other hand, high levels of TIC resulted partly from higher rates of biological production, and partly from decomposition of TOC associated with sediment resuspension. The isotopic signiture in TIC seems to imply that the latter is dominant in forming more TIC in both the YRE and LRE, and there may be transfer of OC to IC in the water column.