基于水淘选分级的长江口及其邻近海域表层沉积物中有机碳的来源、分布和保存  

Sources,distribution,and preservation of size-fractionated sedimentary organic carbon of the Changjiang Estuary and adjacent shelf based on water elutriation

作　　者：王金鹏[1,2] 姚鹏[1,3,4] 孟佳[1,2] 赵彬[1,2] 潘慧慧[1,2] 张婷婷[1,2] 李栋[1,2] 

机构地区：[1]中国海洋大学海洋化学理论与工程技术教育部重点实验室,山东青岛266100 [2]中国海洋大学化学化工学院,山东青岛266100 [3]海洋科学与技术青岛协同创新中心,山东青岛266100 [4]中国海洋大学海洋有机地球化学研究所,山东青岛266100

出　　处：《海洋学报》2015年第6期41-57,共17页

基　　金：国家自然科学基金面上项目"不同来源有机碳在长江口-东海内陆架的水动力分选研究"(41176063)

摘　　要：从分级的角度认识大河三角洲前缘河口沉积有机碳的来源、分布和保存对深刻理解全球碳循环具有重要意义。于2012年6月采集了长江口和浙闽沿岸共6个站位的表层沉积物样品，采用水淘选的方法按照颗粒物水动力直径大小对其进行分级分离，分析了这些分级样品的有机碳含量、稳定同位素、比表面积以及木质素等参数，并且结合蒙特卡洛模拟的三端元混合模型，讨论了此区域不同粒级沉积有机碳的来源、分布和保存特点。结果表明，长江口表层沉积物的有机碳在小粒级中含量较高，如816μm 粒级有机碳含量的均值为1．30％，而3263μm 粒级的均值为0．90％，但是大粒级有机碳对沉积物有机碳的贡献最高（81．3％），这是因为大粒级的质量贡献占绝对优势（72．0％）。三端元混合模型的计算结果表明，长江口表层沉积物中沉积有机碳的贡献以海洋来源为主（平均为73％），土壤和维管植物也有一定贡献（平均值分别为21％和6％）。在小粒级（816μm）中，土壤对于沉积有机碳的贡献显著高于其他粒级，这是由于土壤有机质比较容易富集在细颗粒上。木质素的参数，如 C／V（0．040．32）和 S／V（0．331．23），显示长江口表层沉积物主要来源于草本和木本被子植物的混合，随着粒级的增大，草本被子植物的来源逐渐增多。浙闽沿岸分级沉积物的 OC／SSA＜0．4 mg／m2，而长江口的站位中 OC／SSA＞0．4 mg／m2，表明长江口沉积有机碳的保存效率比浙闽沿岸的高。木质素降解参数，如（Ad／Al）v、3，5－Bd／V 和 P／（S＋V）随着粒级的增大逐渐降低，表明小粒级降解程度较高，而大粒级中降解程度较低。Knowledge of the sources,dispersal and preservation of sedimentary organic carbon in large-river delta-front estuaries （LDE）from the perspective of size fractionation is critical for a better understanding of global car-bon cycling.Surface sediments collected from four stations in the Changjiang Estuary mud area and two stations in the Zhe-Min coastal mud area in July 2012 were separated into different size fractions using the water elutriation method.Organic carbon （OC）and total nitrogen （TN）,stable carbon isotopic composition,specific surface area （SSA）and lignin of these size-fractionated sediments were analyzed to discuss the effect of hydrodynamic sorting on the variation of sources,distribution and preservation of OC in the Changjiang LDE.It has been showed that OC contents are high in the small size fraction,for examples,the average OC contents of 8-16 μm fractions is 1.30%, while for the 32-63 μm fractions it is only 0.90%.However,the contributions of sedimentary OC （up to 81.3%） are dominated in large size fractions because of the dominance of mass contributions in these size fractions （up to 72.0%）.The results of a three end-member mixing model based on Monte-Carlo simulation indicate that marine OC is the predominant OC source （73% in average）,whereas the average contributions of soil and C3 vascular plant are 21% and 6% ,respectively.The contributions of soil OC in small size fractions （such as 8-16 μm）are higher than those of other fractions,consistent with the fact that soil OC prefers to be absorbed on fine particles.The val-ues of lignin source parameters,such as cinnamyl to vanillyl （C/V,0.04 to 0.32）and syringyl to vanillyl （S/V, 0.33 to 1.23）,indicate that these terrigenous organic matter are derived from a mixture of woody and non-woody angiosperms.As the size increases,the contributions of non-woody angiosperms increase.The sediment specific surface area （SSA）normalized OC contents of all size fractions in the Zhe-Min mud area are lower than thos

关 键 词：长江口 沉积有机碳 水动力分选 木质素 来源 降解 

分 类 号：X145[环境科学与工程—环境科学]