中文摘要：

大河影响下的陆架边缘海沉积有机碳的分布和来源是全球碳循环研究的重要内容。本研究于2012年5月采集了渤海海域的29个表层沉积物样品,分析了粒度组成、总有机碳（TOC）、总氮（TN）、木质素含量和稳定碳同位素丰度（δ13C）等参数,结合基于蒙特卡洛模拟的三端元混合模型,定量研究了沉积物中有机碳的分布和来源情况,并讨论了其影响因素。结果表明,研究区域表层沉积物中TOC含量为0.19%～0.81%,渤海中部泥质区站位（大于0.65%）明显高于其周围砂质区域站位（小于0.40%）;TOC与黏土含量也有显著的正相关性,说明细颗粒沉积物容易富集有机碳。沉积有机碳的δ13C范围为-23.7‰～-21.8‰,显示沉积有机碳是海源和陆源有机碳的混合输入。木质素参数,如C/V、S/V和LPVI的数值范围显示研究区域表层沉积物中木质素主要来源于被子植物草本组织与木本组织的混合,同时有少量裸子植物的贡献。基于蒙特卡洛模拟的三端元混合模型显示研究区域沉积物中有机碳主要来源于海洋浮游植物,平均为64%,陆源有机碳中来自土壤的贡献最高（平均为27%）,C3维管植物的贡献较少（平均为9%）。海洋浮游植物有机碳主要分布在渤海中部泥质区及离岸较远的区域,而土壤有机碳和C3维管植物有机碳则主要沉积在河口附近及近岸区,并可以离岸输运到较远的地方。

英文摘要：

Characterizing the distribution and sources of sedimentary organic carbon（SOC）in large-river dominated ocean margins（RiOMars）is an important part of the global carbon cycle research.Surface sediments were collected from 29 sites in the Bohai Sea（BS）in May 2012,and grain size composition,total organic carbon（TOC）,total nitrogen（TN）,stable carbon isotopic composition and lignin-phenols were analyzed to quantitatively study the dispersal and sources of SOC and its influential factors.The results showed that TOC content of surface sediments from the BS ranged broadly from 0.19%to 0.81%,and it was higher in samples from the mud deposit（0.65%）than that from the sandy region（0.40%）.A significant positive relationship was observed between TOC and clay content,indicating that OC is easily associated with fine-grained sediments.Theδ13 C of TOC in this study ranged from-23.7‰to-21.8‰,indicating a mixed contribution of OC from terrestrial and marine sources.The lignin indices,such as C/V,S/V and LPVI,showed that the lignin in surface sediments from the BS were originated from a mixture of woody and non-woody angiosperms,as well as the contribution of gymnosperms.The results of a three end-member mixing model based on Monte-Carlo Simulation indicated that marine OC is the major component of SOC（average 64%）in the study area,followed by soil OC（average 27%）and C3 vacular plant derived OC（average 9%）.The highest marine OC contribution was mainly found in the mud deposit and offshore area of the BS,while soil OC and C3 vacular plant derived OC deposited mainly in the Yellow River estuary and adjacent nearshore areas but could be transported offshore.