CAJ | 학술논문

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8～16μm 粒级有机碳含量的均值为1．30％，而32～63μm 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（8～16μm）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（0．04～0．32）和 S／V（0．33～1．23），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。
종분급적각도인식대하삼각주전연하구침적유궤탄적래원、분포화보존대심각리해전구탄순배구유중요의의。우2012년6월채집료장강구화절민연안공6개참위적표층침적물양품，채용수도선적방법안조과립물수동력직경대소대기진행분급분리，분석료저사분급양품적유궤탄함량、은정동위소、비표면적이급목질소등삼수，병차결합몽특잡락모의적삼단원혼합모형，토론료차구역불동립급침적유궤탄적래원、분포화보존특점。결과표명，장강구표층침적물적유궤탄재소립급중함량교고，여8～16μm 립급유궤탄함량적균치위1．30％，이32～63μm 립급적균치위0．90％，단시대립급유궤탄대침적물유궤탄적공헌최고（81．3％），저시인위대립급적질량공헌점절대우세（72．0％）。삼단원혼합모형적계산결과표명，장강구표층침적물중침적유궤탄적공헌이해양래원위주（평균위73％），토양화유관식물야유일정공헌（평균치분별위21％화6％）。재소립급（8～16μm）중，토양대우침적유궤탄적공헌현저고우기타립급，저시유우토양유궤질비교용역부집재세과립상。목질소적삼수，여 C／V（0．04～0．32）화 S／V（0．33～1．23），현시장강구표층침적물주요래원우초본화목본피자식물적혼합，수착립급적증대，초본피자식물적래원축점증다。절민연안분급침적물적 OC／SSA＜0．4 mg／m2，이장강구적참위중 OC／SSA＞0．4 mg／m2，표명장강구침적유궤탄적보존효솔비절민연안적고。목질소강해삼수，여（Ad／Al）v、3，5－Bd／V 화 P／（S＋V）수착립급적증대축점강저，표명소립급강해정도교고，이대립급중강해정도교저。
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 those of the Changjiang mud area,indicating that long distance transport is unfavorable for the preservation of OC.The lignin decay indices,such as (Ad/Al)v,3,5-Bd/V and P/(S+V)are relatively high in small-size fractions,indicating that fine particles are highly degraded,whereas large-size fractions are characterized by less degradation.