地球科学进展  2018 , 33 (10): 1024-1033 https://doi.org/10.11867/j.issn.1001-8166.2018.10.1024.

综述与评述

海洋沉积物有机质赋存的多样性与物源指标的多疑性综述

韦海伦1, 蔡进功1*, 王国力2, 王学军3

1.同济大学海洋地质国家重点实验室,上海 200092
2.中国石油化工股份有限公司科技部,北京 100086
3.中国石化胜利油田分公司勘探开发研究院,山东 东营 257015

The Diversity of Organic Matter in Marine Sediments and the Suspiciousness of Source Parameters: A Review

Wei Hailun1, Cai Jingong1*, Wang Guoli2, Wang Xuejun3

1.State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China
2. Science and Technology Institute, China Petroleum & Chemical Corporation, Beijing 100086, China;
3. Exploration and Development Institute of Shengli Oilfield Company, Sinopec, Shandong Dongying 257015,China

中图分类号:  P736.21

文献标识码:  A

文章编号:  1001-8166(2018)10-1024-10

通讯作者:  *通信作者:蔡进功(1961-),男,山东烟台人,教授,主要从事海洋沉积学和石油地质学研究.E-mail:jgcai@tongji.edu.cn

收稿日期: 2018-06-7

修回日期:  2018-09-8

网络出版日期:  2018-10-10

版权声明:  2018 地球科学进展 编辑部 

基金资助:  国家自然科学基金项目“泥页岩中不同赋存态烃的分离及特征研究”(编号:41672115)同济大学海洋地质国家重点实验室自主课题探索项目“东海沉积物各类型有机质的来源与保存机制研究”(编号:MG20170201)资助.

作者简介:

First author:Wei Hailun(1991- ), male, Du'an County, Guangxi Province, Ph.D student. Research areas include distribution and source of organic matter in marine sediment and carbon cycle of the ocean. E-mail: 2010weihailun@tongji.edu.cn

作者简介:韦海伦(1991-),男,广西都安人,博士研究生,主要从事海洋沉积物有机质的分布和源汇研究.E-mail:2010weihailun@tongji.edu.cn

展开

摘要

海洋沉积物中有机质类型多样,准确判断有机质的来源具有重要的意义。前人通常的研究方法包括元素比(C/N)、稳定同位素(δ13C)和生物标志物(BIT)等,都以全样作为对象,通过各自的海陆端元值计算比例。然而,有机质通过抗降解性或与无机矿物结合等不同方式保存,其差异导致各自的参数值发生变化。经过重力等作用下分异沉积后,不同保存方式的有机质便会富集或分散,使得有些指标在某区域失真甚至失去意义。由此可知,全样测得的有机质各参数值受其来源和保存方式共同影响,不考虑保存方式而直接使用这些指标来研究有机质来源便具有不可靠性。基于此,提出粒级分离的方法,将不同性质和保存方式的沉积物分离,并根据具体粒级的有机质组成和特征,使用相应的指标及端元值,得到更准确的有机质来源比例。这对认识有机质的产生、聚集、赋存、运移、沉积和演化等整个碳循环过程具有深刻意义。

关键词: 海洋沉积物 ; 有机质来源 ; 粒级分离 ; 指标参数

Abstract

There are various types of Organic Matter (OM) in marine sediments, and it is of great significance to accurately estimate the source of them. The methods used in most researches include element ratio (C/N), stable isotopes (δ13C) and biomarkers (BIT), all of which are used for the whole sample as objects and calculated by end-member of terrestrial and marine source OM, respectively. However, OM is preserved in different ways, such as on its own recalcitrance or combining with inorganic minerals. Preservation differences make their respective parameter values change. After differential sedimentary by gravity or other factors,different preservation types of OM are enriched or dispersed, making some parameters distorted and even meaningless in some areas. Therefore, the parameters of OM measured by the whole sample are influenced by the source of OM and the way of deposition and preservation. Therefore, it is unreliable to use these parameters to study the source of OM without considering the way of preservation. Based on this, this paper put forward a method of particle separation to separate the sediment in different propertied and preservation types. According to the composition and characteristics of the OM at the specific grain level, the corresponding index and end-members value were used to calculate more accurate proportion of the OM. It is of profound significance to understand the production, aggregation, occurrence, migration and deposition of OM and its evolution in the entire carbon cycle.

Keywords: Marine sediment ; Source of organic matter ; Particle classification ; Parameter

0

PDF (1888KB) 元数据 多维度评价 相关文章 收藏文章

本文引用格式 导出 EndNote Ris Bibtex

韦海伦, 蔡进功, 王国力, 王学军. 海洋沉积物有机质赋存的多样性与物源指标的多疑性综述[J]. 地球科学进展, 2018, 33(10): 1024-1033 https://doi.org/10.11867/j.issn.1001-8166.2018.10.1024.

Wei Hailun, Cai Jingong, Wang Guoli, Wang Xuejun. The Diversity of Organic Matter in Marine Sediments and the Suspiciousness of Source Parameters: A Review[J]. Advances in Earth Science, 2018, 33(10): 1024-1033 https://doi.org/10.11867/j.issn.1001-8166.2018.10.1024.

1 引 言

海洋是有机质聚集、沉积、储存和演化的重要场所[1,2,3],也是碳循环中重要的源与汇区[4]。有机质只有最终进入沉积物中,才能够进行长周期保存[5]。因此,准确识别海洋沉积物中不同来源有机质特征和数量极其重要。

海洋沉积物中有机质的来源和类型丰富多样,其性质和保存方式各不相同。木质、丝炭等陆源高等植物碎片具有较强的疏水性,在自身抗降解作用下保存[6];河流中的土壤胶粒是有机质的缩聚,包裹在无机矿物内,保存完好[7];粪球粒、群体或链状的浮游植物可独立沉降[8];而细颗粒有机质和可溶有机质(Dissolved Organic Carbon,DOC),不管是陆源还是海源,都可以与无机矿物结合而形成絮凝体[9],在无机矿物的保护下保存。当陆源有机质输入海洋之后,与海洋有机质相混合,在不同环境条件下发生分异沉积,导致不同海域的陆源与海源有机质的比例差异较大,这对区分沉积物中有机质类型和混合比例提出了挑战。由此看来,有机质的来源、类型、性质和保存方式等都会造成有机质沉积的复杂性,故准确判断有机质的来源和比例就显得非常重要。

为有效区分沉积物中陆源与海源有机质的比例,前人做了大量的工作,如利用有机质的有机碳同位素(δ13C)[10]、元素比(C/N)[11]和生物标志物指标(Branched and Isoprenoid Tetraether index,BIT)[12]等方法,检测沉积物中各参数值,结合海源和陆源有机质的端元值,利用二端元法来计算海陆有机质的比例,进而探讨有机质的源汇。该方法的关键点是陆源和海源的端元值的确定。部分研究者以河流悬浮物[13]平均值作为陆源端元值,以开放海域的表层沉积物[13]或不含木质素的样品对应的参数值[14]作为海源端元值。更有甚者,部分研究者直接使用其他海域的端元值而不考虑研究区的具体情况[15]。然而,前人研究发现,沉积有机质包括颗粒态和有机黏粒复合体,保存的差异使得有机质的特征参数发生不同步的变化[16],使得相同来源的有机质的特征参数亦有差异。当有机质发生分异沉积时,不同类型和保存方式的有机质便会分离,并在不同的海域沉积,导致其在某些区域富集或稀释,而其他区域大量减少甚至已经不存在[17],使得不同沉积区域中指示有机质来源的指标参数的海陆端元值发生变化。因此,在不考虑海陆端元值变化的情况下,通过全样来进行研究时,得到的有机质来源及其比例便具有较大的不可靠性,导致不同参数计算出来的结果有时差异较大甚至得出矛盾的结论。

本文综合前人研究成果,从生物化学、地球化学和表现形式等角度论述陆源与海源有机质的性质差异,指出有机质保存方式的差异及其对物源指标参数的影响,探讨不同参数的应用范围,并建议通过粒级分离的方式解决有机质保存方式差异带来的问题。

2 海洋沉积有机质的来源与保存

2.1 有机质的来源和性质

海洋沉积物中的有机质分为陆源有机质和海洋自生有机质2种。由于陆源和海源有机质的初级生产者在生活习性和生命形态等各方面的差异,它们在生物化学和地球化学的性质和表现形式上也并不相同。

陆源有机质通过河流和大气输送到海洋中,主要是陆地植物碎片及其孢粉、土壤中的腐殖质和微生物降解产物,以及沉积岩被冲刷侵蚀后淋滤出来的有机质[6]。河流搬运的陆源有机质主要以高等植物碎片、有机质絮凝体、土壤胶粒和DOC的形式存在[6]。高等植物碎片主要包括木质和丝炭等,其木质素含量高而具有很强的抗降解性,可以独立运移和沉积;无机矿物比表面积大,具有吸附性,能够吸附细微颗粒有机质和DOC,形成有机质絮凝体,在运移过程中不断发生有机质的吸附—解吸附作用[9,18];土壤胶粒颗粒细[19]携带的有机质高度降解[20],性质稳定;DOC在河流运输的有机质中占有很大的一部分,条件合适时在海洋中絮凝[21]。海洋自生有机质,主要是浮游生物、游泳生物和底栖生物的残体、分泌物及其降解产物等[22],主要存在形式包括动植物残体、粪球粒、有机质絮凝体和DOC等[8]。粪球粒、群体或链状的浮游植物可独立沉降[8];细颗粒有机质和DOC在透明胞外聚合物的作用下,聚合形成有机质絮凝体,颗粒粒径大于500 μm时称为“海雪”[23]。由此可知,陆源和海源有机质类型丰富,性质不一。当陆源有机质进入海洋之后,与海源有机质进行相应的混合,包括物理混合、絮凝和吸附等,以不同的形式存在。

2.2 有机质的保存与沉积

陆源和海源有机质在混合之后,会在不同条件下沉降。陆源高等植物等结构有机质在自身抗降解作用下保存,有机质絮凝体可在无机矿物的保护下摆脱微生物的利用而保存[9,24],土壤包裹的有机质在土壤颗粒的保护下保存。这些保存形式不同的有机质的形态、大小、密度、与无机矿物的关系等因素都会影响它们的沉降,使得它们以不同的比例分布于不同的区域。

河口是不同来源有机质混合的典型区域。以长江口为例,杨丽阳等[14]研究发现,在长江口门处的沉积物中,包含高等植物碎屑、土壤源有机质和海源有机质;唐建华等[25]通过现场观测,了解长江口细颗粒泥沙在水动力和盐度变化下的絮凝过程。前人研究表明,絮凝过程是细颗粒有机质和DOC聚集沉降的主要方式[1],以絮凝体的方式聚集之后便会沉降于河口[26]。由此可知,在同一区域的沉积物中,沉积了不同类型和保存方式的有机质。东海在各种条件综合作用下形成多个泥质区和砂质区,沉积有机质类型的比例差异较大。朱纯等[27]对东海的现代沉积物中正构烷烃分子组合特征的研究中,发现长江及邻近海域的物源分为陆源优势区域和陆海内生混合区域;王敏[28]对东海泥质区沉积物中的木质素分布特征进行研究,发现济州岛西南泥质区的木质素含量比内陆架泥质区低。这些都表明东海不同区域的物源比例差异较大。

有机质的来源多样,除了海源和陆源的区分外,在多河流交汇区域,还需具体分析不同河流或土壤有机质的贡献比例。不同有机质保存方式的差异使得有机质在运移和沉降过程中分异沉积,使得不同区域有机质比例的差异。

3 有机质的保存与特征指标变化

陆源和海源有机质的保存方式多样,并且以不同的比例聚集于不同的海域。区分陆源与海源有机质参数很多,包括元素比、特征元素的同位素和生物标志物等,其各具有自身的优缺点(表1)。下面就有机碳同位素、C/N值和BIT这3个参数与保存的关系进行论述,探讨有机质的保存差异对参数指标可靠性的影响。

表1   有机质来源参数的异同

Table 1   Differences and similarities of different source parameters of organic matter

名称原理优点缺点
有机碳同位素δ13C海陆植物的光合作用差异使其优先使用不同的CO2,导致C分馏差异,使得海陆有机质的碳同位素有差异[29]同位素值较为稳定,在运移沉降过程中变化小[30]C3、C4和CAM(Crassulacean Acid Metabolism)植物的δ13C不同,因而在多种植物繁盛区域,它们的差异使得结果出现偏差[31]
C/N值由于陆地和海洋植物的木质素、纤维素和蛋白质含量差异,使得海陆有机质的C/N值不同[32]①准确判定物源趋势;②在环境稳定区域的柱状样中,若其值稳定,则可判定微生物降解作用影响较小[30]①C/N值的变化:有机质在早期成岩过程中,蛋白质优先降解会造成 C/N偏高[30];无机铵盐的吸附作用会造成 C/N 偏低,当沉积物的颗粒粒度较小时这种影响会增大[29]
②有机碳含量较低时(<0.3%),无机氮对于C/N的影响不可忽略[31]
BIT海洋中的古菌和陆地土壤的细菌生物标志物不同,从而可据此判断物源[12]海洋古菌和土壤微生物的生物标志物GDGTs(图1)具有相似的化学结构及降解速率,因而受降解影响较小[12]①生物标志物GDGTs在不同粒级中保存有差异,多存于细粒级中[33],因而砂质区域使用受限
②不能指示通过大气运输进入海洋的陆源有机质[31]

新窗口打开

3.1 有机碳同位素

有机碳同位素是判断有机质来源的常用指标[34,35]。陆源高等植物和海洋藻类在光合作用过程中,CO2的同位素分馏差异,导致产生的有机质δ13C值并不相同。一般,陆源有机质的δ13C值为-26‰,海洋有机质的δ13C值为-21‰左右[36],并以此作为海陆端元值。通过测试得到的研究区样品的有机碳同位素值,利用二端元法,便得到有机质的海陆比例。

前人通过相关海域的δ13C值变化,来研究有机质的分布规律和运移路径。Cai等[37]通过南黄海不同深度悬浮物和沉积物的δ13C值变化,得出陆源有机质主要来源于废黄河口、现代黄河和长江三处的混合;Ramaswamy等[13]通过δ13C值计算出安达曼海近岸区域的有机质物源比例,并得出伊洛瓦底江输出的陆源有机碳主要往东边和南边运移的结论。然而,计算得到的有机质海陆比例及由此得出的相关结论可靠与否,都在于陆源和海源端元值的选择。

陆源有机质通过河流搬运入海,但研究发现河流的河底沉积物、悬浮物或颗粒有机质(Particle Organic Carbon,POC)和DOC的δ13C并不相同[20,38]。Wang等[39]对黄河和长江的研究发现,DOC的同位素值分别是-25.6‰ ~-32.1‰ 和-28.8‰ ~-32.1‰,平均分别较POC轻4.78‰和5.85‰;Hedges等[20]对亚马逊研究发现,悬浮物的δ13C比河底沉积物平均轻1.4‰;即使在悬浮物中不同粒级的有机质,其碳同位素也有差异,如Hedges等[20]对亚马逊悬浮物分为大于63 μm和小于63 μm,发现细粒级的同位素值较粗粒级轻约0.5‰。河底有机质、大颗粒有机质主要是高等植物等结构有机质,细颗粒有机质主要是破碎的有机质和小颗粒的絮凝体,DOC主要是生物释放和POC的降解。也就是说,不同赋存形式的有机质,其δ13C并不相同。

当这些有机质进入海洋中,并以不同比例沉积于不同区域时,陆源有机质的端元值便会发生变化。因而在使用-26‰作为固定的陆源端元值来计算海陆比例,便会得到不可靠的结果。

3.2 C/N

C/N(重量比)是一种常用的物源指标参数[11,40],通常和有机碳同位素一同作为有机质的来源指标[30]。陆地植物一般由贫N的木质素和纤维素组成,而海洋浮游植物缺乏纤维素而富含蛋白质[41],相对富N,因而两者C/N有差异。通常,陆源有机质的C/N值>12,海源为6~9[42]

前人通过C/N值的变化,探讨有机质的来源和分布规律,但也遇到矛盾之处。晁海娟等[43]在研究长江口及邻近海域的有机质物源变化时,C/N在长江口123.5°E出现高值中心,其解释为赤潮爆发,且该处为水动力强,有机质易于降解,而蛋白质优先被降解。然而,东海赤潮的藻类主要是甲藻、硅藻、裸藻等海洋浮游植物[44],因而赤潮高发区的有机质主要为海源[45]。此外,有机质的降解由有机质自身的抗降解性、无机矿物、氧化还原条件等综合因素共同决定[46],与水动力条件并不直接相关。张明亮等[47]通过C/N和δ13C研究莱州湾沉积物有机质来源时,通过端元法计算出陆源有机质为负的近岸区域,且靠近点的百分比差异巨大。这些结果都是不可靠的。

不同类型的有机质,其保存方式有差异。陆源结构有机质中,含N的官能团易于被微生物作为N源使用,留下的主要是结构N,使得C/N值较大[11]。然而,在有无机矿物特别是黏土矿物吸附保护或有机质聚合包裹的情况下,隔绝了生物降解作用,因而无机矿物含量高的细粒级中,含有易降解氨基酸等[6]。此外,在运移的过程中,选择性降解或不断吸附包括含N有机质的DOC、细颗粒物或无机氮,使得C/N值发生变化[48]。Hedges等[20]在对亚马逊河部分河段和支流研究时发现,大于63 μm的粗颗粒,其C/N平均值为21,而小于63 μm的细粒级,其平均值为9。可以说,赋存于细颗粒中的陆源有机质,其C/N值趋向于海源。细颗粒与粗颗粒沉降区域并不一致,会导致计算的结果出现差异或矛盾。

3.3 BIT

BIT是Hopmans提出的基于古菌和细菌的生物标志物指标[12]。古菌和细菌等微生物细胞膜脂的主要成分是甘油双烷基甘油四醚(Glycerol Dialkyl Glycerol Tetraethers, GDGTs,图1)。其中crenarchaeol存在于海水、河流、湖泊及土壤中,但主要是由海洋浮游古菌合成[50,51];Branched GDGTs I-III(bGDGTs)主要由土壤中的厌氧细菌(Anaerobic Bacteria)合成,并通过地表径流输入海区[12,50]。因此,通过两者的含量比例关系可以了解有机质来源。BIT的公式如下:

BIT= I+II+IIII+II+III+IV[12],

图1   Branched GDGTs和crenarchaeol的结构及利用HPLC-MS单离子扫描的m/z[49]

Fig.1   Structures of Branched GDGTs and crenarcheol, as well as their m/z values for SIM HPLC-MS analyses[49]

式中:I, II, III分别是bGDGTs I, II, III的含量,IV是crenarchaeol的含量;BIT取值为0~1。当BIT值为0时,表示有机质全部来源于海洋自生;当BIT值为1时,表示陆源有机质比例为100%。这就有了陆源和海源的特征,从而能够通过它的值来看有机质海陆比例。该参数的本质就是将bGDGTs作为陆源有机质的代表,将crenarchaeol作为海源有机质的代表,将两者的量进行对比而得到结果。

然而,GDGTs在沉积物中并非均匀存在。Li等[52]对长江沉积物中的bGDGTs与有机碳(Organic Carbon,OC)进行检测,结果表明,两者变化趋势具有一致性,但是并非等比例的增长或下降(图2a)。此外,土壤厌氧细菌合成的bGDGTs I-III溶于河流中,或随土壤颗粒运移[53]。溶于河流中需要被无机矿物吸附才能沉降,因而其多吸附并保存于细颗粒物中,粗颗粒物中含量较低。从图2b可以看出,bGDGTs与黏土含量的变化具有一致性。其次,从图2c中可以看出,bGDGTs含量与中值粒径呈一定的负相关关系,且在粒径超过一定大小之后,bGDGTs含量非常低,接近于零。Peterse等[54]对土壤与河岸进行分粒级研究,结果表明,使用总有机碳(Total Organic Carbon,TOC)标准化后的bGDGTs的量,在小于63 μm细粒级中,含量最高。在海洋中,GDGTs不能通过自身重力沉降,而需要吸附于沉积颗粒之上并随之沉降[55]。Ingalls 等[56]对普吉特海湾悬浮物的分离实验表明,62%的GDGTs保存在0.7~60 μm粒级中,而大于60 μm粒级中保存的GDGTs含量仅为2%。

图2   bGDGTs分别与OC、黏土含量和沉积物中值粒径的变化关系(数据来源于参考文献[52])

Fig.2   The relationship between bGDGTs and OC, clay content, median grain size, respectively (data from reference[52])

从上述表述可以看出,GDGTs在沉积物中的含量不均匀,且与TOC的变化不同步。其主要保存于细粒级中,而在粗粒级中不易保存。因而,BIT参数在一定意义上仅可指示细粒级中有机质的来源;而当粒级较粗时,GDGTs含量低,不能代表不同来源的有机质,因而不能使用这个参数。不同海域的沉积物粒径分布差异较大,有砂质区泥质区等。因此,使用该参数来指示物源,应当要考虑有机质保存的差异。

以上3种方法,是通过陆海源有机质的性质差异或某种特征有机质的含量比例来表征的。然而,陆源和海源有机质各自也有不同的类型,其保存方式的差异导致指标参数值并不一致,或因保存于沉积物不同粒径中导致其参数值不代表全样。当陆源有机质入海之后,与海洋有机质混合,并在不同条件下分异沉降,这些指标参数值差异的有机质便在不同的区域重新组合沉积,使得各区域陆源和海源的端元值并不完全一致,因而若使用相同的端元值来计算海陆比例,得到的结果便不可靠或相互矛盾。此外,对不同赋存的有机质来说,并非所有的参数都适用。絮凝体有机质在运移沉降过程中对无机氮的吸附引起C/N值变化而不可使用该参数[48];陆源植物碎屑多储存与粗粒级中,GDGTs含量很低而不使用BIT参数;δ13C值变化较小,仅需要确定不同赋存有机质的海陆端元值即可。因此,有机质赋存的差异使得某一指标参数仅能显示部分有机质或局部区域的信息,不能代表全样或全区域的有机质信息。我们需要将不同赋存的有机质分离开来,排除因赋存或其他因素而受干扰的参数,才能得到较为准确的结果。

4 多参数指标下的矛盾及解决方案

4.1 多参数指标变化的不一致性

研究有机质来源和分布时,为了避免单一指标的局限性,通常使用多指标参数进行综合对比分析。王润梅等[15]结合δ13C和C/N值综合研究环渤海地区河流河口及海洋表层沉积物有机质特征和来源,葛田田等[57]通过C/N值和BIT指标等综合分析过去100年济州岛西南泥质区有机质来源变化。然而,各参数的变化并不一致,甚至相互矛盾。在王润梅等[15]的研究中,δ13C显示陆源有机质对渤海地区的有机质贡献为10%~50%,然而从C/N值来看,大部分区域的陆源贡献为100%;在葛田田等[57]的研究中,C/N值和BIT的变化并不完全一致,特别是1986—2006年,两者在部分层段的变化完全相反,指示的物源变化相反。由此可知,即使使用多参数,避免单一指标的局限性,得到的结果也是模糊不定的,得到的结论也仅显示为海陆混合的结果,而进一步的海陆比例及由此延伸的有机质运输路径等其他结论,都不能令人信服。

有机质的类型丰富多样,保存方式具有差异性,使其δ13C和C/N等参数值并不一致。在细粒级中,δ13C偏负而更具陆源特征,C/N值偏低而更具海源特征;此外,GDGTs多存于细粒级中,粗粒级中含量很低。当陆源有机质输入海洋,与海源有机质混合沉降。不同保存方式的陆源或海源有机质并非集体沉降,而是随环境变化分异沉积,粗颗粒的结构有机质等沉积于河口,而细颗粒有机质则可运移至更远的区域。此外,在水环境复杂的区域,有机质还会经历沉降—悬浮—再沉降—再悬浮的循环过程而分选。因此,不同海域海陆有机质的组合类型并不一致,使得相应指标参数的端元值发生差异。当我们在整个海域使用同一端元值,甚至使用其他海域的端元值进行计算时,得到的结果就不可靠,不同的参数得到的结果便会不一致甚至是矛盾的。由此可知,要正确区分有机质的海陆比例,必须考虑不同类型有机质保存的差异。

4.2 沉积物粒级分离

不同保存方式的有机质会以不同的组合方式分布,结构有机质等大颗粒有机质能够克服自身重力而沉积下来,而细颗粒有机质或无定形有机质则会与无机矿物结合,形成聚合体而沉积。王金鹏等[58]对长江口及浙闽沿岸的表层沉积物有机质来源进行分粒级研究,结果表明小于16 μm的粒级,木质素含量极少,且随着粒径的逐渐增加,木质素的含量逐渐增大。蔡进功等[59]对长江口表层沉积物孢粉相特征研究中发现,小于2 μm粒级主要以无定形有机质为主。蔡进功等[59]通过对长江口沉积物进行粒级分离后发现,大于125 μm粒级主要由木质、丝炭组成,2~125 μm粒级木质丰富,且出现藻团块、角质组织、粪球粒等,而小于2 μm粒级几乎全部为无定形有机质。因此,不同类型和保存方式的有机质集中于不同的粒级中,既有陆源也有海源,因而将沉积物按照粒径分离开来,在一定程度上能够将全样中不同赋存方式的有机质进行富集,排除某些参数局限性的干扰,使用合适的物源判断参数及相应的端元值进行计算,从而得到较准确的结论。

4.3 各粒级端元指标参数的确定与计算

由于不同粒级中有机质类型和保存方式的差异性,并非所有的指标参数都适合使用,且其相应海陆端元值也不一样。因此,选择适合的指标参数及其端元值是准确测定海陆有机质分布的关键。

在陆源端,采集河流中靠近入海口且不受海洋影响的下游相邻数个河段的悬浮物,并对其进行粒级分离,以此作为各粒级陆源端指标参数选择和端元值确定的样品。使用有机质含量的参数(如BIT)判断海陆比例时,则将各粒级样品进行色谱分析或其他方法来测定该有机质的含量,并测试该粒级的总有机碳,了解使用的该有机质的含量与TOC的比值关系,若其比值较高,且在相邻河段中的相同粒级中,其值较为稳定时,则可以选择该参数,并将该值作为陆源端元值。使用有机质的特征作为指标参数时(如C/N,δ13C),需要对各粒级样品进行分别检测,选择相同粒级中,检测值稳定的指标参数,并将该值作为该粒级的陆源端元值。海源端元值较为复杂。海洋中的透光层是初级生产力产生的主要场所,且在这一层段,有机质的循环和消耗严重,仅有5%~25%的有机质可以从透光层沉降下去[60]。因而,我们可以选择在海洋生物繁盛区域下的透光层下相邻的不同区域采集悬浮物作为确定指标的样品,然后进行粒级分离,采取与陆源相同的步骤进行各粒级选用指标的确定及其端元值的检测。当各粒级所使用的指标参数及其相应的海陆与岸断指确定之后,便可以计算出研究海域各粒级中的海陆有机质比例,随后根据粒级分布情况,算出全样中有机质的海陆比例。

5 结 论

海洋沉积物中的有机质从产生到沉积经过了非常复杂的运移、聚集和沉降过程。在此过程中,不同的有机质会被不同程度地降解、循环和保护,使有机质自身的特性与最初始的生物源相比发生变化,相应的指标参数也具有差异性。可以说,沉积物中的有机质特性由来源和保存过程2个因素共同控制。陆源有机质入海并与海源有机质混合,在不同的外界环境下分异沉降,使得不同有机质在不同粒级中富集或稀释。因此,我们在评估沉积物有机质的海陆比例时,不能笼统地使用全样作为研究对象来评估,而应该考虑不同的保存方式对指标参数的影响,进行粒级分离,然后通过对各粒级的综合研究来获得有机质的海陆比例,进而得到与此相关的其他结论。这对准确了解有机质的聚集、赋存、运移、沉积和演化等整个碳循环过程具有非常重要的意义。

The authors have declared that no competing interests exist.


参考文献

[1] Druffel E R M, Williams P M, Bauer J E, et al.

Cycling of dissolved and particulate organic matter in the open ocean

[J]. Journal of Geophysical Research Oceans, 1992, 97(C10): 15 639-15 659.

DOI      URL      [本文引用: 2]      摘要

Radiocarbon (020014C), 020713C, bulk carbon and organic constituent concentration measurements are presented for dissolved and particulate carbon pools from the North Central Pacific Ocean (NCP) and the Sargasso Sea (SS). We operationally define three overlapping pools of dissolved organic carbon (DOC): (1) DOC that is oxidizable by UV radiation (DOCuv); (2) 090008extra090009 DOC measured by Co/CoO flow-through high-temperature catalytic oxidation (DOCFt-htc), which also has low 020014C values like DOCuv (Bauer et al., 1992a); and (3) a potential residual DOC fraction that is the difference between DOC measured by discrete-injection high-temperature catalytic oxidation (DOChtc) and DOCFt-htc, and which has unknown 020014C signature. The distribution of a large fraction of DOC appears to be controlled by circulation of deep ocean waters between major oceans. The DOC in the SS is slightly younger than would be expected if circulation was the sole process controlling DOC cycling. We propose that there is more bomb 14C in the deep SS DOC to account for this difference. The 020014C values of suspended, and to a lesser extent sinking particulate organic carbon (POC), decrease with depth, with the suspended POC displaying a much steeper gradient in the SS than in the NCP. These data reflect the incorporation of low-activity organic matter into the POC pool, possibly through incorporation of DOC by physical adsorption and/or biological heterotrophy.
[2] Hare A A, Kuzyk Z Z A, Macdonald R W, et al.

Characterization of sedimentary organic matter in recent marine sediments from Hudson Bay, Canada, by Rock-Eval pyrolysis

[J]. Organic Geochemistry, 2014, 68: 52-60.

DOI      URL      [本文引用: 1]      摘要

A combination of Rock-Eval pyrolysis and isotopic analyses is used to characterize the sources and distribution of organic matter in modern marine sediments from the subarctic Hudson Bay (including Hudson Strait and Foxe Basin), Canada. This approach reveals organic matter contributions from both marine and terrigenous sources, with spatial patterns and varying degrees of degradation that are consistent with inferences from traditional geochemical tracers for modern organic matter. Rock-Eval parameters characterize Hudson Bay organic matter with low hydrogen index, high oxygen index and a high degree of residual carbon that suggests heavily reworked materials. Locations of higher primary productivity in Hudson Strait, Foxe Basin, the northeast and far west of Hudson Bay, and the concentration of watershed runoff in the southern part of Hudson Bay can be delineated using the ratios between hydrogen and oxygen indices and from the distribution of labile organic carbon. Relatively high temperatures of peak hydrocarbon yield identify an advanced state of OM degradation or humic substances as important classes of organic carbon compounds in the majority of the sediment. Such highly degraded and oxygenated organic matter is unusual compared to that typically observed in other Arctic shelf seas and is consistent with a strong role for sediment and organic matter recycling in Hudson Bay. In the offshore region, the source of highly oxidized and labile organic matter identified by Rock-Eval parameters is resolved with 13C and biomarker information that also permit examination of the sediment biogeochemical regime. This approach suggests that a distinct association with Mn enriched sediment contributes to the oxidization signal by abiotic or biological Mn related processes. These interpretations extend the limited information available on using Rock-Eval analyses to characterize organic matter in recently deposited marine sediments and describe an important consideration to using this method in Mn enriched environments.
[3] Ren Chengzhe, Yuan Huamao, Song Jinming, et al.

Amino sugars and their indicating role in the cycling of organic matter in marine environment

[J]. Advances in Earth Science, 2017, 32(9): 959-971.

[本文引用: 1]     

[任成喆, 袁华茂, 宋金明, .

海洋环境中的氨基糖及其在有机质循环过程中的指示作用

[J]. 地球科学进展, 2017, 32(9): 959-971.]

DOI      URL      [本文引用: 1]      摘要

氨基糖作为海洋环境中一类具有重要地球化学特征的有机质,其在海水、颗粒物和沉积物中的含量和组成等信息能够有效反映有机质的来源、降解过程及成岩状态。从氨基糖的来源与组成、海洋环境中的分布特征和影响因素,以及其作为生物标志物对有机质来源和降解状态的指示作用等方面,系统总结了海洋环境中氨基糖的研究进展。结果表明,氨基糖的活性受其大分子形态、环境中溶解氧、营养盐水平和沉积环境的影响。葡萄糖胺/半乳糖胺(Glc N/GalN)和总可水解氨基酸/总可水解氨基糖(THAA/THAS)对有机质来源和降解状态的指示具有一致性,较高的Glc N/GalN和THAA/THAS值可反映浮游生物来源的新鲜有机质,其比值的降低表明有机质逐渐向细菌有机质转化。氨基糖的碳、氮归一化含量对二者的指示具有差异性,其比例的升高和降低取决于有机质降解程度和来源影响的相对贡献大小。胞壁酸可用于估算较为新鲜的细菌有机质对总有机质的贡献,但由于其快速循环而导致在溶解有机质中的含量极低,不适合应用在溶解有机质中。今后的工作应进一步加强不同微生物对海洋环境中氨基糖的贡献,区分有机质来源和降解对氨基糖的影响以及转化和归宿研究。
[4] Ridgwell A, Zeebe R E.

The role of the global carbonate cycle in the regulation and evolution of the Earth system

[J]. Earth & Planetary Science Letters, 2005, 234(3/4): 299-315.

DOI      URL      [本文引用: 1]      摘要

We review one of the most ancient of all the global biogeochemical cycles and one which reflects the profound geochemical and biological changes that have occurred as the Earth system has evolved through time hat of calcium carbonate (CaCO 3). In particular, we highlight a Mid-Mesozoic Revolution in the nature and location of carbonate deposition in the marine environment, driven by the ecological success of calcareous plankton. This drove the creation of a responsive deep-sea sedimentary sink of CaCO 3. The result is that biologically driven carbonate deposition provides a significant buffering of ocean chemistry and of atmospheric CO 2 in the modern system. However, the same calcifying organisms that under-pin the deep-sea carbonate sink are now threatened by the continued atmospheric release of fossil fuel CO 2 and increasing acidity of the surface ocean. We are not yet in a position to predict what the impact on CaCO 3 production will be, or how the uptake of fossil fuel CO 2 by the ocean will be affected. This uncertainty in the future trajectory of atmospheric CO 2 that comes from incomplete understanding of the marine carbonate cycle is cause for concern.
[5] Burdige D J.

Preservation of organic matter in marine sediments: Controls, mechanisms, and an imbalance in sediment organic carbon budgets?

[J]. Chemical Reviews, 2007, 107(2): 467-485.

DOI      URL      [本文引用: 1]     

[6] Hedges J I, Keil R G, Benner R.

What happens to terrestrial organic matter in the ocean?

[J]. Marine Chemistry, 1997, 27(5/6): 195-212.

DOI      URL      [本文引用: 4]      摘要

Each year rivers transport approximately 0.25 10 15 g of dissolved (0.5 m) organic carbon (POC) from continents to the ocean. Global discharge of riverine DOC is sufficient alone to sustain turnover of the entire pool of organic carbon dissolved in seawater. Similarly, the input of terrestrial POC by rivers is adequate to supply all the organic carbon buried in marine sediments. Because riverine organic matter consists of highly degraded, nitrogen-poor remains of terrestrial organisms, it might be expected to suffer minimal respiration in the ocean. One of the biggest mysteries in the global carbon cycle, therefore, is that only a small fraction of the organic matter dissolved in seawater and preserved in marine sediments appears to be land-derived. Either our global budgets and distribution estimates are greatly in error, or both dissolved and particulate organic matter of terrestrial origin suffer rapid and remarkably extensive remineralization at sea. Although many uncertainties remain, recent studies provide growing evidence for destruction of both dissolved and particulate terrestrial organic matter in the ocean. The mechanisms by which these huge masses of organic materials might be so rapidly oxidized following discharge are largely unknown. This report focuses on the transport and transformations of land-derived organic matter in the ocean, highlighting recent research on the patterns and processes involved.
[7] Mikutta R, Kleber M, Torn M S, et al.

Stabilization of soil organic matter: Association with minerals or chemical recalcitrance?

[J]. Biogeochemistry, 2006, 77(1): 25-56.

DOI      URL      [本文引用: 1]      摘要

Soil organic matter (OM) can be stabilized against decomposition by association with minerals, by its inherent recalcitrance and by occlusion in aggregates. However, the relative contribution of these factors to OM stabilization is yet unknown. We analyzed pool size and isotopic composition (0166C, 0106C) of mineral-protected and recalcitrant OM in 12 subsurface horizons from 10 acidic forest soils. The results were related to properties of the mineral phase and to OM composition as revealed by CPMAS 0106C-NMR and CuO oxidation. Stable OM was defined as that material which survived treatment of soils with 6 wt% sodium hypochlorite (NaOCl). Mineral-protected OM was extracted by subsequent dissolution of minerals by 10% hydrofluoric acid (HF). Organic matter resistant against NaOCl and insoluble in HF was considered as recalcitrant OM. Hypochlorite removed primarily 0166C-modern OM. Of the stable organic carbon (OC), amounting to 2.4-20.6 g kg6301 soil, mineral dissolution released on average 73%. Poorly crystalline Fe and Al phases$(\text{Fe}_{\text{o}},\text{Al}_{\text{o}})$and crystalline Fe oxides$(\text{Fe}_{\text{d}-\text{o}})$explained 86% of the variability of mineral-protected OC. Atomic$\text{C}_{\text{p}}/(\text{Fe}+\text{Al})_{\text{p}}$ratios of 1.3-6.5 suggest that a portion of stable OM was associated with polymeric Fe and Al species. Recalcitrant OC (0.4-6.5 g kg6301 soil) contributed on average 27% to stable OC and the amount was not correlated with any mineralogical property. Recalcitrant OC had lower Δ0166C and δ0106C values than mineral-protected OC and was mainly composed of aliphatic (56%) and O-alkyl (13%) C moieties. Lignin phenols were only present in small amounts in either mineral-protected or recalcitrant OM (mean 4.3 and 0.2 g kg6301 OC). The results confirm that stabilization of OM by interaction with poorly crystalline minerals and polymeric metal species is the most important mechanism for preservation of OM in these acid subsoil horizons.
[8] Turner J T.

Zooplankton fecal pellets, marine snow, phytodetritus and the ocean's biological pump

[J]. Progress in Oceanography, 2015, 130: 205-248.

DOI      URL      [本文引用: 3]      摘要

The iological pump is the process by which photosynthetically-produced organic matter in the ocean descends from the surface layer to depth by a combination of sinking particles, advection or vertical mixing of dissolved organic matter, and transport by animals. Particulate organic matter that is exported downward from the euphotic zone is composed of combinations of fecal pellets from zooplankton and fish, organic aggregates known as arine snow and phytodetritus from sinking phytoplankton. Previous reviews by Turner and Ferrante (1979) and Turner (2002) focused on publications that appeared through late 2001. Since that time, studies of the biological pump have continued, and there have been >300 papers on vertical export flux using sediment traps, large-volume filtration systems and other techniques from throughout the global ocean. This review will focus primarily on recent studies that have appeared since 2001. Major topics covered in this review are (1) an overview of the biological pump, and its efficiency and variability, and the role of dissolved organic carbon in the biological pump; (2) zooplankton fecal pellets, including the contribution of zooplankton fecal pellets to export flux, epipelagic retention of zooplankton fecal pellets due to zooplankton activities, zooplankton vertical migration and fecal pellet repackaging, microbial ecology of fecal pellets, sinking velocities of fecal pellets and aggregates, ballasting of sinking particles by mineral contents, phytoplankton cysts, intact cells and harmful algae toxins in fecal pellets, importance of fecal pellets from various types of zooplankton, and the role of zooplankton fecal pellets in picoplankton export; (3) marine snow, including the origins, abundance, and distributions of marine snow, particles and organisms associated with marine snow, consumption and fragmentation of marine snow by animals, pathogens associated with marine snow; (4) phytodetritus, including pulsed export of phytodetritus, phytodetritus from Phaeocystis spp., picoplankton in phytodetritus, the summer export pulse (SEP) of phytodetritus in the subtropical North Pacific, benthic community responses to phytodetritus; (5) other components of the biological pump, including fish fecal pellets and fish-mediated export, sinking carcasses of animals and macrophytes, feces from marine mammals, transparent exopolymer particles (TEP); (6) the biological pump and climate, including origins of the biological pump, the biological pump and glacial/interglacial cycles, the biological pump and contemporary climate variations, and the biological pump and anthropogenic climate change. The review concludes with potential future modifications in the biological pump due to climate change.
[9] Ding Xiaoling, Henrichs M.

Adsorption and desorption of proteins and polyamino acid by clay minerals and marine sediments

[J]. Marine Chemistry, 2002, 77: 225-237.

DOI      URL      [本文引用: 3]      摘要

The adsorption and desorption of proteins and polyamino acids on illite, montmorillonite, goethite, and marine sediments was investigated. Three 14C-labeled hydrophilic proteins, Rubisco from C. reinhardtii, and GroEL and GroES from genetically modified Escherichia coli, were synthesized and purified for this study. The proteins were strongly and rapidly adsorbed by the clay minerals and marine sediments, and much of the adsorbed protein was not readily desorbed. Sodium dodecyl sulfate (SDS) extraction and separation by SDS-polyacrylamide gel electrophoresis (PAGE) and sucrose density gradients showed that Rubisco and GroEL were adsorbed on illite and sediments in their original forms. The apparent adsorption partition coefficients of the proteins were on the order of 10 2 l/kg on illite, 10 3 10 4 l/kg on goethite and montmorillonite, and 200 and 75 l/kg on Skan Bay and Resurrection Bay (Alaska) sediments, respectively. These partition coefficients are sufficiently large to permit sedimentary protein preservation via an adsorptive mechanism. Generally, basic polyamino acids had greater adsorption partition coefficients than acidic polyamino acids. Molecular size did not affect the electrostatic interaction between polyamino acids and mineral surfaces. Adsorption of bovine serum albumin (BSA) and negatively charged polyamino acids inhibited Rubisco adsorption, while positively charged cytochrome c and polyamino acids increased Rubisco adsorption. These results indicate that electrostatic interactions dominated in protein adsorption.
[10] Krishna M S, Naidu S A, Subbaiah C V, et al.

Sources, distribution and preservation of organic matter in a tropical Estuary (Godavari, India)

[J]. Estuaries & Coasts, 2015, 38(3): 1 032-1 047.

DOI      URL      [本文引用: 1]      摘要

Major sources and distribution of organic matter (OM) were examined in a tropical monsoonal estuary, the Godavari, using content and isotopic signatures in suspended particulate matter and surface sediments during no-discharge period. The lower (1002km) estuaries have shown remarkably different features with reference to the sources, distribution and preservation of OM. The upper estuary is characterized by relatively high content of particulate organic carbon (POC) and chlorophyll-a (Chl-a) and low suspended matter and sediment OC. In contrast, the lower estuary is characterized by relatively low content of particulate OC and Chl-a and high suspended matter and sediment OC. Our data and model results showed that suspended particulate OM is derived predominantly from freshwater phytoplankton in the upper (658502%) and lower (656002%) estuaries, with a minor contribution from estuarine phytoplankton (652502%) and terrestrial C 3 plants (651002%) in the lower estuary, during the study period. On the other hand, sediment OM in the upper and lower estuaries derived from both autochthonous and allochthonous sources with nearly equal contributions. Although relatively high in situ production was observed in the upper than the lower estuary, relatively low sediment OC was found in the former than the latter region, suggesting that strong influence of preservation conditions rather than surface biological production on OC accumulation in sediments. This is attributed to intense transformation of OM by heterotrophs in the upper than the lower estuary because of prevailing conducive conditions for degradation of OM in the upper estuary during the study period.
[11] Albuquerque A L S, Mozeto A A.

C∶ N∶ P ratios and stable carbon isotope compositions as indicators of organic matter sources in a riverine wetland system (Moji-guaçu River, São Paulo-Brazil)

[J].Wetlands, 1997, 17(1): 1-9.

DOI      URL      [本文引用: 3]     

[12] Hopmans E C, Weijers J W H, Schefu β E, et al.

A novel proxy for terrestrial organic matter in sediments based on branched and isoprenoid tetraether lipids

[J]. Earth & Planetary Science Letters, 2004, 224(1): 107-116.

DOI      URL      [本文引用: 5]      摘要

We propose a novel tracer for terrestrial organic carbon in sediments based on the analysis of tetraether lipids using high-performance liquid chromatography/mass spectrometry (HPLC/MS). Analysis of terrestrial soil and peats shows that branched tetraether lipids are predominant in terrestrial environments in contrast to crenarchaeol, the characteristic membrane lipid of non-thermophilic crenarchaeota, which is especially abundant in the marine and lacustrine environment. Based on these findings, an index was developed, the so-called Branched and Isoprenoid Tetraether (BIT) index, based on the relative abundance of terrestrially derived tetraether lipids versus crenarchaeol. This BIT index was applied to surface sediments from the Angola Basin, where it was shown to trace the outflow of the Congo River. Furthermore, analyses of particulate organic matter from the North Sea showed relatively higher BIT indices in water column particulate organic matter near large river inputs. A survey of globally distributed marine and lacustrine surface sediments shows that the BIT index in these environments correlates with the relative fluvial input of terrestrial organic material making this index generally applicable. The new proxy allows the rapid assessment of the fluvial input of terrestrial organic material in immature sediments up to 100 Ma old.
[13] Ramaswamy V, Gaye B, Shirodkar P V, et al.

Distribution and sources of organic carbon, nitrogen and their isotopic signatures in sediments from the Ayeyarwady (Irrawaddy) continental shelf, northern Andaman Sea

[J]. Marine Chemistry, 2008, 111(3/4): 137-150.

DOI      URL      [本文引用: 3]      摘要

Total organic carbon (TOC), total nitrogen (TN) and their δ 13C and δ 15N values were determined from 110 sediment samples from the Ayeyarwady (Irrawaddy) continental shelf, northern Andaman Sea to decipher the concentration and source of organic matter. Comparatively higher TOC and TN concentrations are found in the inner-shelf mud belt, and on the continental slope sediments, whereas the outer-shelf sediments, composed mostly of relict sands, are low in TOC. The TOC contents are positively correlated with the abundance of fine-grained sediments. The TOC:TN ratios and δ 13C and δ 15N values show low variability within the modern inner-shelf mud belt and Gulf of Martaban, indicating similar source. The TOC:TN ratios are mostly between 6 and 8 in the inner-shelf mud belt and these values are similar to the suspended sediments in the Ayeyarwady and Salween rivers. The δ 13C values of organic matter increase from 61 25‰ in the Gulf of Martaban to about 61 22‰ in the slope regions indicating decreasing terrestrial input away from the coast. The δ 15N values on the Ayeyarwady shelf are rather low (+ 3.3 to + 4.8‰), especially off the mouths of the Ayeyarwady River mouths, reflecting greater influence of freshwater and terrigenous sediment discharge. A simple two end-member carbon mixing model applied to the Ayeyarwady shelf region indicates that terrigenous sources contribute more than 70% of the organic carbon in the modern mud belt in the inner shelf and Gulf of Martaban. Terrigenous organic carbon percentages reduce gradually offshore, reducing to less than 60% near the continental shelf edge. A strong terrigenous signal is preserved in the inner shelf and Gulf of Martaban sediments probably because organic matter from the source region is not subject to intensive processing and replacement in the floodplains and deltaic regions as well as rapid burial at sea.
[14] Yang Liyang, Wu Ying, Zhang Jing, et al.

Distribution of lignin and sources of organic matter in surface sediments from the adjacent area of the Changjiang Estuary in China

[J]. Acta Oceanologica Sinica, 2008, 30(5): 35-42.

[本文引用: 2]     

[杨丽阳, 吴莹, 张经, .

长江口邻近陆架区表层沉积物的木质素分布和有机物来源分析

[J]. 海洋学报, 2008, 30(5): 35-42.]

DOI      URL      [本文引用: 2]      摘要

对长江口邻近陆架区表层沉积物的有机物进行碳、氮元素、碳稳定同位素和木质素测定,以分析其物质来源,特别是陆源有机物的迁移埋藏。结果表明,碳与氮含量的比值为6.2-7.7,δ^13C为-19.9×10^-3--22.4×10^-3。8种木质素酚单位的总含量(相对于总有机碳)为0.15×10^-2-1.56×10^-2mg/mg,显著低于长江口门处的2.50×10^-2mg/mg。香草基酚类的酸醛比平均值为0.90,表明该海区的陆源有机物是高度降解的;紫丁香级酚类与香草基酚类的含量之比为(0.78±0.35),肉桂基酚类与香草基酚类的含量之比为(0.13±0.08),表明这些陆源有机物源于草本和木本混合的被子植物。31.5°N以南站位木质素的降解程度比北部的高,草本植物源的贡献更大,被子植物的主导优势也更明显;长江输入的有机物以沿岸堆积为主,具有显著的离岸降低趋势。在31.5°N以北的陆架区,虽然近岸站位陆源有机物的贡献显著高于其他站位,但其他站位并没有离岸递减趋势。这种南北分布差别可能是由海流条件和水深梯度的差异引起的。计算结果显示,该海区表层沉积物中的陆源有机物占总有机物的5%-57%,且主要来自土壤有机质。
[15] Wang Runmei, Tang Jianhui, Huang Guopei, et al.

Provenance of organic matter in estuarine and marine surface sediments around the Bohai Sea

[J]. Oceanologia et Limnologia Sinica, 2015, 46(3): 497-507.

Magsci      [本文引用: 3]     

[王润梅, 唐建辉, 黄国培, .

环渤海地区河流河口及海洋表层沉积物有机质特征和来源

[J]. 海洋与湖沼, 2015, 46(3): 497-507.]

DOI      URL      Magsci      [本文引用: 3]      摘要

2013 年8 月采集了环渤海地区35 条主要河流河口表层沉积物样品, 12 月采集了渤海与北黄海24 个表层沉积物样品, 分析了其生物地球化学指标: 总有机碳(TOC)、总氮(TN)、有机碳同位素(δ<sup>13</sup>C)和氮同位素(δ<sup>15</sup>N), 探讨该区域表层沉积物有机质特征及组成。研究表明: 河流河口表层沉积物有机碳同位素(δ<sup>13</sup>C)值在-26.4‰— -21.8‰, 平均值为-24.5‰; 渤海表层沉积物有机碳同位素(δ<sup>13</sup>C)值在-23.8‰— -21.7‰, 平均值为-22.3‰。河口表层沉积物TOC 含量在0.06%—3.87%, 平均值为1.31%; 渤海表层沉积物TOC 含量在0.52%—2.09%, 平均值为1.08%。河流δ<sup>13</sup>C 富集较轻, 偏向陆源; 海洋δ<sup>13</sup>C 富集较重, 偏向水生有机质来源。河流河口表层沉积物的δ<sup>13</sup>C 值差异较明显, 最大值与最小值相差4.6‰, 但是流域地理位置距离近的河流δ<sup>13</sup>C 值差异不大。河流河口表层沉积物δ<sup>15</sup>N 在1.5‰—10.2‰, 平均值为5.5‰; 渤海表层沉积物δ<sup>15</sup>N 在4.4‰—5.6‰, 平均值为5.0‰。河流表层沉积物δ<sup>15</sup>N 范围比渤海表层沉积物δ<sup>15</sup>N 范围广, 原因是河流受陆源有机物影响, 且陆源有机物来源差异大。海洋表层沉积物δ<sup>15</sup>N 相对均一, 说明海洋表层沉积物δ<sup>15</sup>N 受物源影响较小, 体现了水体中有机质的转化和微生物活动对氮同位素的影响。本研究中表层沉积物的δ<sup>13</sup>C 与δ<sup>15</sup>N 没有明显的相关性, 也体现了陆源有机质输入的影响。根据经典的二元模式计算, 35 条河流陆源有机质的贡献比例范围为10%—90%, 平均值为60%; 渤海陆源贡献比例范围为10%—50%, 平均值为20%。河流有机质的来源以陆源有机质为主, 水生有机质为辅。渤海有机质的来源以水生有机质为主, 环渤海河流的陆源输入也有重要贡献。需要指出的是, 有机碳同位素(δ<sup>13</sup>C)、氮同位素(δ<sup>15</sup>N)和Corg/Ntotal 对有机质来源判别有一定局限性, 虽然稳定同位素有示踪性, 然而其成分仍然不可避免地受到生物地球化学等过程的改造, 在使用稳定同位素技术示踪物源时, 须小心谨慎。
[16] Lehmann M F, Bernasconi S M, Barbieri A, et al.

Preservation of organic matter and alteration of its carbon and nitrogen isotope composition during simulated and in situ early sedimentary diagenesis

[J]. Geochimica et Cosmochimica Acta, 2002, 66(20): 3 573-3 584.

DOI      URL      [本文引用: 1]      摘要

The carbon and nitrogen isotope composition of organic matter has been widely used to trace biogeochemical processes in marine and lacustrine environments. In order to reconstruct past environmental changes from sedimentary organic matter, it is crucial to consider potential alteration of the primary isotopic signal by bacterial degradation in the water column and during early diagenesis in the sediments. In a series of oxic and anoxic incubation experiments, we examined the fate of organic matter and the alteration of its carbon and nitrogen isotopic composition during microbial degradation. The decomposition rates determined with a double-exponential decay model show that the more reactive fraction of organic matter degrades at similar rates under oxic and anoxic conditions. However, under oxic conditions the proportion of organic matter resistent to degradation is much lower than under anoxic conditions. Within three months of incubation the δ 13C of bulk organic matter decreased by 1.6‰ with respect to the initial value. The depletion can be attributed to the selective preservation of 13C-depleted organic compounds. During anoxic decay, the δ 15N values continuously decreased to about 3‰ below the initial value. The decrease probably results from bacterial growth adding 15N-depleted biomass to the residual material. In the oxic experiment, δ 15N values increased by more then 3‰ before decreasing to a value indistinguishable from the initial isotopic composition. The dissimilarity between oxic and anoxic conditions may be attributed to differences in the type, timing and degree of microbial activity and preferential degradation. In agreement with the anoxic incubation experiments, sediments from eutrophic Lake Lugano are, on average, depleted in 13C (611.5‰) and 15N (611.2‰) with respect to sinking particulate organic matter collected during a long-term sediment trap study.
[17] Prasad V, Garg R, Singh V, et al.

Organic matter distribution pattern in Arabian Sea: Palynofacies analysis from the surface sediments off Karwar coast (west coast of India)

[J]. Systematic & Applied Microbiology, 2007, 20(3): 492-503.

[本文引用: 1]     

[18] Satterberg J, Arnarson T S, Lessard E J, et al.

Sorption of organic matter from four phytoplankton species to montmorillonite, chlorite and kaolinite in seawater

[J]. Marine Chemistry, 2003, 81(1): 11-18.

DOI      URL      [本文引用: 1]     

[19] Hedges J I, Clark W A, Quay P D, et al.

Compositions and fluxes of particulate organic material in the Amazon River

[J]. Limnology & Oceanography, 1986, 31(4): 717-738.

DOI      URL      [本文引用: 1]      摘要

Lignin, elemental, and stable carbon isotope compositions are reported for local plants and for coarse $(> 63 \mu m)$ and fine $(< 63 \mu m)$ suspended particulate materials collected along a 1,950-km reach of the lower Amazon River during four contrasting stages of the 1982-1983 hydrograph. Fluxes of chemically recognizable lignin in the two size classes generally parallel each other along the mainstem with the fine fraction usually predominating. Particulate organic matter transported in the coarse size fraction of the mainstem and its major tributaries is composed of recently formed and well preserved tree leaf debris along with some wood. Organic matter in the fine size fraction is comparatively old, degraded, and rich in immobilized nitrogen and derives primarily from soils. C-4 grasses, which are abundant in the mainstem floodplain (varzea), are not major components of either the coarse or fine particulate material in the river. Particulate organic matter in both size fractions is introduced largely from upstream sources within the Rio Solimo es and Rio Madeira drainage basins. Most of this organic matter is unreactive and is transported conservatively with mineral particles along the Amazon mainstem. However, some downstream compositional trends are seen in both size fractions which reflect the addition or exchange of highly degraded, 13C-depleted, and lignin-poor organic materials from lower basin sources.
[20] Hedges J I, Cowie G L, Richey J E, et al.

Origins and processing of organic matter in the Amazon River as indicated by carbohydrates and amino acids

[J]. Limnology & Oceanography, 1994, 39(4): 743-761.

DOI      URL      [本文引用: 5]      摘要

Aldose, amino acid, and elemental compositions were determined for flux-weighted samples of coarse $(>63 \mu m)$ and fine $(<63 \mu m)$ particulate organic material and ultrafiltered (>1,000 Daltons) dissolved organic matter collected at three sites along the Brazilian Amazon River and six of its major tributaries, Concentrations of total organic C (TOC) were relatively uniform $(550 \pm 100 \mu M)$ at all sites, with DOC comprising the major (50-100%) component. An average of 77% of the total DOC was isolated by ultrafiltration. The greatest compositional differences observed in the Amazon River system were among the coarse, fine, and dissolved organic fractions. All coarse particulate fractions were nitrogen-poor (atomic C;N = 21) and exhibited stable carbon isotope, aldose, and amino acid compositions similar to those of angiosperm tree leaves. Coarse particulate organic materials, although the least degraded of the three fractions, had lost appreciable carbohydrate and had immobilized excess nitrogen of apparent bacterial origin. Fine particulate materials were more nitrogen-rich (C:N = 9) than coarse counterparts and had lower total aldose yields and glucose percentages. Fine particles gave greater total yields of amino acids, characterized by high ratios of basic vs. acidic components. Coexisting dissolved organic materials recovered by ultrafiltration were nitrogen-poor (C:N = 27-52) and yielded the lowest amounts of aldoses, among which deoxy sugars were concentrated. Dissolved fractions gave extremely low yields of amino acids in mixtures that were enriched in nonprotein components and in acidic vs. basic molecules. These yields and composition patterns are consistent with a "regional chromatography" model in which highly degrated leaf material is solubilized and then partitioned between soil minerals and water during transport to the river, resulting in suspended fine particulate organic materials of soil origin that are nitrogen-rich and coexisting dissolved organic substances that are nitrogen-poor.
[21] Avneri-Katz S, Young R B, McKenna A M,et al.

Adsorptive fractionation of Dissolved Organic Matter (DOM) by mineral soil: Macroscale approach and molecular insight

[J]. Organic Geochemistry, 2017, 103: 113-124.

DOI      URL      [本文引用: 1]      摘要

Our findings suggest that a significant amount of carbon originating from the applied DOM was irreversibly stabilized by mineral surfaces. The study demonstrates that both DOM chemical heterogeneity and DOM concentration need to be considered in order to predict DOM reactivity and carbon stabilization in soils.
[22] Duan Yi.Marine and Marsh Sedimentary Organic Geochemistry[M]. Beijing: Science Press, 2008.

[本文引用: 1]     

[段毅. 海洋和沼泽沉积有机地球化学[M]. 北京:科学出版社,2008.]

[本文引用: 1]     

[23] Macquaker J H S, Keller M A, Davies S J.

Algal Blooms and "Marine Snow": Mechanisms that enhance preservation of organic carbon in Ancient Fine-Grained Sediments

[J]. Journal of Sedimentary Research, 2010, 80(11): 934-942.

DOI      URL      [本文引用: 1]      摘要

Combined petographic and geochemical methods are used to investigate the microfabrics present in thin sections prepared from representative organic carbon-rich mudstones collected from three successions (the Kimmeridge Clay Formation, the Jet Rock Member of the Whitby Mudstone Formation, and the pebble shale and Hue Shale). This study was initiated to determine how organic carbon-rich materials were being delivered to the sediment-water interface, and what happened to them after deposition, prior to deep burial. Analyses of the fabrics present shows that they exhibit many common attributes. In particular they are all: (1) highly heterogeneous on the scale of a thin section, (2) organized into thin beds (< 10 mm thick) composed mainly of mineral mixtures of fine-grained siliciclastic detritus and carbonate materials, and (3) contain significant concentrations of organic carbon, much of which is organized into laminasets that contain abundant organomineralic aggregates and pellets. In addition, framboidal pyrite (range of sizes from < 20 urn to < 1 ??m) and abundant agglutinated foraminifers are present in some units. The individual beds are commonly sharp-based and overlain by thin, silt lags. The tops of many of the beds have been homogenized and some regions of the pelleted laminasets contain small horizontal burrows. The organomineralic aggregates present in these mudstones are interpreted to be ancient examples of marine snow. This marine snow likely formed in the water column, particularly during phytoplankton blooms, and was then transported rapidly to the seafloor. The existence of the thin beds with homogenized tops and an in-situ infauna indicates that between blooms there was sufficient oxygen and time for a mixed layer to develop as a result of sediment colonization by diminutive organisms using either aerobic or dysaerobic metabolic pathways. These textures suggest that the constituents of these mudstones were delivered neither as a continuous rain of sediment nor were the bottom waters persistently anoxic. In addition, the presence of thin lags and sharp-based beds suggests that the seafloor was being episodically reworked during deposition. These fabrics indicate that conditions in the water columns and at the seafloors while these rocks were being deposited were very dynamic, and episodic fluxes of high concentrations of organic carbon to the seafloor, during phytoplankton blooms, likely enhanced preservation of organic carbon. Copyright ?? 2010, SEPM (Society for Sedimentary Geology).
[24] Sugai S, Henrichs S.

Rates of amino acid uptake and mineralization in Resurrection Bay (Alaska) sediments

[J]. Marine Ecology Progress, 1992, 88(2/3): 129-141.

DOI      URL      [本文引用: 1]      摘要

The rates of uptake and mineralization of glutamic acid, alanine, lysine, serine and glycine were measured in sediments from Resurrection Bay, Alaska, USA, using C-14-labeled amino acids. Amino acid concentrations and specific activities were determined by high performance liquid chromatography. The fate of radiolabeled amino acids added to killed control sediments was also investigated. Free amino acids were lost from the dissolved pool by both bacterial uptake and adsorption to sediment particles. Adsorption was the dominant process for the basic amino acid lysine and was responsible for about half of the glutamic acid and alanine removal from solution. Rates of bacterial mineralization of porewater amino acids, calculated using a model which corrects for the effects of adsorption, were 8 (glutamic acid), 1 (alanine), 0.7 (lysine), 1 (serine) and 3 (glycine) nmol cm-3 sediment d-1. These rates indicate that amino acids could be quantitatively important intermediates in the mineralization of organic nitrogen in this sediment.
[25] Tang Jianhua, He Qing, Wang Yuanye, et al.

Study on in-situ flocs size in turbidity maximum of the Changjiang Estuary

[J]. Journal of Sediment Research, 2008, (2): 27-33.

[本文引用: 1]     

[唐建华, 何青, 王元叶, .

长江口浑浊带絮凝体特性

[J]. 泥沙研究, 2008, (2): 27-33.]

[本文引用: 1]     

[26] Jiang T, Skyllberg U, Björn E, et al.

Characteristics of Dissolved Organic Matter (DOM) and relationship with dissolved mercury in Xiaoqing River-Laizhou Bay Estuary, Bohai Sea, China

[J]. Environmental Pollution, 2017, 223: 19-30.

DOI      URL      PMID      [本文引用: 1]      摘要

61In Xiaoqing River-Laizhou Bay estuary system, distinct DOM properties of two end-members were clearly identified.61Laizhou Bay estuary area was more inclined to be influenced by riverine rather than marine DOM sources.61Xiaoqing River-Laizhou Bay estuary system displayed no significant correlation between DOM and Hg.61Quasi-conservative behavior of DOM but non-conservative behavior of Hg might explain the decoupling relation of DOM vs. Hg.61Environmental role of DOM is hardly generalized due to influence of different biogeochemical processes on the given system.
[27] Zhu Chun, Pan Jianming, Lu Bing, et al.

Compositional feature of n-alkanes in modern sediment from the Changjiang Estuary and adjacent area and its implication to transport and distribution of organic carbon

[J]. Acta Oceanologica Sinica, 2005, 27(4): 59-67.

[本文引用: 1]     

[朱纯, 潘建明, 卢冰, .

长江口及邻近海域现代沉积物中正构烷烃分子组合特征及其对有机碳运移分布的指示

[J]. 海洋学报, 2005, 27(4): 59-67.]

DOI      URL      [本文引用: 1]      摘要

Concentration and composition feature of -alkanes in modern sediments from the Chang jiang Estuary and adjacent area are reported.Factor statistical analysis method is used to study the source of -alkanes.The result shows that -alkanes distribution patterns are charact erized by three modes:the beside peak mode which indicates abundant of terrest rial plant origin,dual peaks mode indicating both terrestrial plant and marine biological input and petroleum contamination mode.The chromatogram proxies mutation of -alkanes in border the stations of at Changjiang Estuary is the objective reflection of sediment diversity resulting from two types of different water masses.Relationship between E -Alk and TOC retains a postcor relation at all stations except P4,and TER-Alk,PL-1 and CPI are all highly correlated to the distance at the ZJ section.Factor statistical analysis reveals 4 types of input,among those the contribution of ter restrial plantinput is the largest one(51.5%),and among the terrestrial plantinputs the contribution of the Changjiang River discharge is the largest one(49.1%).In terms of diversity of factor load,it is supposed that the sedimentaryorganic matter in the area of middle-northern East China Sea is mostly trans-ported from North Jiangsu Province Coast and the old Huanghe River subaqueus delta,but a majority of sedimentary organic matter in Okinawa Trough may be come from Changjiang River and the inner shelf of East China Sea,and then its migration mechanism is discussed.
[28] Wang Min.

The Distribution Characteristic of Lignin and Its Indication for Terrigenous Organic Matters in Sediments from Mud Areas of the East China Sea

[D]. Shandong: Ocean University of China,2013.

[本文引用: 1]     

[王敏.

东海泥质区沉积物中木质素的分布特征及其对陆源有机物的指示作用

[D]. 山东:中国海洋大学,2013.]

[本文引用: 1]     

[29] Hu Limin, Guo Zhigang, Feng Jialiang, et al.

Distributions and sources of bulk organic matter and aliphatic hydrocarbons in surface sediments of the Bohai Sea, China

[J]. Marine Chemistry, 2009, 113(3): 197-211.

DOI      URL      [本文引用: 2]      摘要

Surface sediment samples from a matrix of fifty-five sites covering virtually the entire Bohai Sea (Bohai), China were analyzed for total organic carbon (TOC), total nitrogen (TN), n-alkanes, unresolved complex mixture (UCM), biomarkers and stable carbon isotopic composition ( δ 13C), and principal component analysis was performed for source identification of organic matter (OM). The distribution of organic carbon correlated well with sediment grain size with the finest sediments having the highest concentration, suggesting the influence of hydrodynamics on the accumulation of sedimentary organic matter (SOM). The corrected TOC/ON (organic nitrogen) ratios and δ 13C indicated mixed marine and terrestrial sources of SOM. Results suggested that δ 13C could be used as a potential indicator to observe the dispersion of Huanghe-derived sediments in Bohai. Total n-alkane concentrations varied over 10-fold from 0.39 to 4.9402μg g 61 1 (dry weight) with the maximum terrigenous/aquatic alkane ratio observed at the Huanghe River Estuary (HRE) due to more higher plant OM from riverine inputs. C 12–C 22 n-alkanes with even-to-odd predominance were observed in several central-eastern Bohai sites. The HRE and its adjacent area is the main sink for the Huanghe river-derived OC. The ubiquitous presence of UCM, biomarkers (hopanes and steranes) and PCA results indicated the presence of petroleum contamination in Bohai, mainly from offshore oil exploration, discharge of pollutants from rivers, shipping activities and atmospheric deposition.
[30] Andrews J E, Greenaway A M, Dennis P F.

Combined carbon isotope and C/N ratios as indicators of source and fate of organic matter in a poorly flushed, tropical estuary: Hunts bay, Kingston Harbour, Jamaica

[J]. Estuarine Coastal & Shelf Science, 1998, 46(5): 743-756.

DOI      URL      [本文引用: 4]      摘要

Stable carbon isotopes and C/N ratios of particulate organic matter (POM) in suspended solids, surficial sediments and sediment cores were used to define the spatial and temporal variability of POM in a poorly flushed, urbanized, eutrophic tropical estuary (Hunts Bay, Kingston Harbour, Jamaica). C/N variation in the sediment surface POM is a function of initial suspended particulate organic matter (SPOM) (or other POM) type and the alteration of C/N ratios in the water column or on the sediment surface. The δ 13 C SPOM (6120 to 6125‰) values suggest that this material is a mixture of: (1) in situ phytoplankton organic matter; (2) terrestrial river-borne SPOM; (3) terrestrial river-borne bottom sediment POM; and (4) sewage. Downcore variation in organic carbon content, C/N and δ 13 Cis attributed mainly to change in the supply rate and type of organic matter. In the NE of Hunts Bay, down core variation in sedimentology and geochemistry are consistent with a change from fully marine to freshwater runoff-dominated sedimentation with increasing organic matter input from sewage in recent times. Despite large overlaps in the C/N and δ 13 C org ‘02end-members02’ pollutant POM, in this case sewage, was the only source which could account for the amount of POM deposited, the surface sediment C/N and δ 13 C org values and the trajectories of evolution in C/N and δ 13 C org values in cores. The data show that the combined δ 13 C and C/N successfully identifies the source, fate and history of POM even in a poorly-mixed estuary.
[31] Ge Tiantian.

Multi-proxy Records of Terrestrial and Marine Organic Matter Sources and Burial in Marginal Sea Sediment over Different Time Scale

[D]. Shandong: Ocean University of China, 2013.

[本文引用: 3]     

[葛田田.

边缘海不同时间尺度有机质来源变化的多参数指标研究

[D]. 山东:中国海洋大学, 2013.]

[本文引用: 3]     

[32] Jia Guodong,

Peng Ping'an. Organic biogeochemistry and past global change

[J]. Earth Science Frantiers, 2005, 12(2): 179-187.

[本文引用: 1]     

[贾国东, 彭平安.

有机生物地球化学与晚新生代古全球变化研究

[J]. 地学前缘, 2005, 12(2): 179-187.]

DOI      URL      [本文引用: 1]      摘要

有机生物地球化学在古全球变化 研究中的应用越来越受到重视。在古海洋学领域,表层海水温度、海洋初级生产力的大小及其种群结构的变化对全球碳循环的影响、海底甲烷释放等关键性科学问题 都需要有机生物地球化学积极参与。有机生物地球化学也能在陆地古生态系统中植被的演变、C3与C4植物的消长变化、湖泊水体环境的变化等方面作出独特的贡 献。文中简要评述了上述内容的研究现状。
[33] Peterse F, Eglinton T I.

Grain size associations of branched tetraether lipids in soils and riverbank sediments: Influence of hydrodynamic sorting processes

[J]. Frontiers in Earth Science, 2017, 5(49): 1-8.

[本文引用: 1]     

[34] Peterson B J.

Stable isotopes as tracers of organic matter input and transfer in benthic food webs: A review

[J]. Acta Oecologica, 1999, 20(4): 479-487.

DOI      URL      [本文引用: 1]     

[35] Gontharet S, Mathieu O, Lévêque J, et al.

Distribution and sources of bulk Organic Matter (OM) on a tropical intertidal mud bank in French Guiana from elemental and isotopic proxies

[J]. Chemical Geology, 2014, 376(22): 1-10.

DOI      URL      [本文引用: 1]      摘要

61Topography and bed elevation explain the spatio-temporal variations of OM sources61SPM is the main OM source with minor amounts from microphytobenthos and mangroves61Higher microphytobenthos contributions are linked to the presence of black laminae
[36] Ogrinc N, Fontolan G, Faganeli J, et al.

Carbon and nitrogen isotope compositions of organic matter in coastal marine sediments (the Gulf of Trieste, N Adriatic Sea): Indicators of sources and preservation

[J]. Marine Chemistry, 2005, 95(3): 163-181.

DOI      URL      [本文引用: 1]      摘要

Terrestrial organic carbon (OC) preserved in marine sediments is an important reservoir in the global carbon cycle, but remains poorly constrained. We determined the elemental and C- and N-isotopic compositions of organic material (OM) in surface sediments and sediment cores from the Gulf of Trieste (N Adriatic), an area characterized by relatively high riverine input. This multiple tracer approach permits evaluation of how sensitive each tracer is for constraining the terrestrial component of OM. Using the relevant terrestrial and marine OM end-members, we estimate that the terrestrial contribution ranges from about 90% at the mouth of the Isonzo River and decreases to ≤10% in the center of the Gulf. In the southern part of the Gulf, 32–44% of terrestrial OC is contributed from smaller rivers, while the δ 15N values of OM reflect more effective nutrient utilization. Analyses of different size fractions show that smaller particles are consistently more organic-rich and tend to be transported further from the river mouth, depending on river discharge. In the size fraction 2–16 μm, elemental ratios and δ 13C org and δ 15N isotopic signatures are consistent with a sedimentary OM pool dominated by bacterially derived biomass. Radiocarbon analyses of sedimentary OC yield depleted Δ 14C values (61338.7‰ to 61429.4‰), indicating a significant fraction of relatively old OC. The natural abundance of 13C and 14C tracers suggests a two-component mixture of ancient and modern C in the sediments down to approximately 60 cm sub-bottom, with an estimated 6545% of sedimentary OC probably being derived from ancient sedimentary OC (kerogen). In addition, there is a significant change in the source of organic material downcore in these sediments which, along with geological evidence, indicate contributions from freshwater swamps typical of coastal lakes with intermittent connections to the sea (brackish) prior to 659000 BP. Depth variations in a core from a salt marsh further indicate temporal variability of OM deposition and transformations in a changing brackish-marine environment in the past.
[37] Cai Deling, Shi Xuefa, Zhou Weijian, et al.

Sources and transportation of suspended matter and sediment in the southern Yellow Sea: Evidence from stable carbon isotopes

[J]. Chinese Science Bulletin, 2003, 48(Suppl.1): 21-29.

DOI      URL      [本文引用: 1]     

[38] Ran Lishan, Lu X X, Sun Huiguo, et al.

Spatial and seasonal variability of organic carbon transport in the Yellow River, China

[J]. Journal of Hydrology, 2013, 498: 76-88.

DOI      URL      [本文引用: 1]      摘要

In this study, we examined the spatial and seasonal variability in the concentrations of dissolved and particulate organic carbon (DOC and POC) of the Yellow River. Weekly samples of water and suspended solids were collected along the main stem channel between July 2011 and July 2012 for the upstream Toudaoguai and Tongguan stations, and between August 2008 and July 2012 for the downstream Lijin station near the river mouth. The DOC export at the upstream two stations was primarily controlled by hydrological events such as melting of ice and snow with high DOC concentrations occurring in spring. In contrast, it was more affected by human activities, mainly reservoir regulation, at the lowermost Lijin station. Lower DOC concentration in the wet season indicates that most of the leachable DOC in surface soils may have largely been flushed away by spring floods. In addition, it is also likely due to dilution effect of the rapidly increased water discharge. As a result of low organic carbon content in the parent soils, the Yellow River sediments were characterized by low POC content (POC%). The averaged POC% at Toudaoguai, Tongguan, and Lijin was 0.48%, 0.47%, and 0.37%, respectively, which is significantly lower than the global mean of around 0.95%. The POC% decreased exponentially with total suspended solids (TSS) concentration. This is likely due to the dilution of riverine POC, because high TSS generally means a higher proportion of coarse sediments that have more mineral matter. During the study period, the total DOC and POC fluxes into the ocean were estimated at 0.06 1012g/yr and 0.41 1012g/yr, respectively. Combining our previous estimate of dissolved inorganic carbon (DIC) export shows that the Yellow River transports a carbon flux of 1.52 1012g/yr into the Bohai Sea, accounting for about 0.19% of the global total riverine carbon flux (DOC+POC+DIC). The extremely low DOC/POC ratio represents the lowest level among major world rivers, which is consistent with its intense soil erosion and highlights the effect of soil erosion on organic carbon export.
[39] Wang Xuchen, Ma Haiqing, Li Ronghua, et al.

Seasonal fluxes and source variation of organic carbon transported by two major Chinese Rivers: The Yellow River and Changjiang (Yangtze) River

[J]. Global Biogeochemical Cycles, 2012, 26(2).DOI.10.1029/2011GB004130.

URL      [本文引用: 1]      摘要

[1] A one-year study was carried out to investigate the seasonal fluxes and source variation of organic carbon transported by two major Chinese rivers, the Yellow River and Changjiang. In 2009, the Yellow River and Changjiang transported 3.20 0103 1010g and 1.58 0103 1012 g DOC and 3.89 0103 1011g and 1.52 0103 1012 g POC, respectively. The dominant input of the terrestrial organic matter occurred during the high discharge period from June to July for the Yellow River and from June to August for Changjiang, accounting for 3609000944% of the DOC and 7209000986% of the POC transported by the two rivers in 2009. The Yellow River transported much higher concentrations of inorganic carbon than organic carbon, while a reverse trend was found in the Changjiang, indicating the different sources of carbon discharged by the two rivers. Using radiocarbon and stable carbon isotope measurements, we identified the different sources and seasonal variations of organic carbon transported by the Yellow River and Changjiang. The Yellow River carried old POC with radiocarbon ages ranging from 4000 to 8000 years, while POC transported by Changjiang had a relatively younger 14C age ranging from 800 to 1060 years. The 14C ages of DOC were relatively younger (3050900091570 years) and showed less variation between the two rivers. The seasonal variations found in 14C ages of DOC and POC indicate that a large fraction of recent-fixed labile organic carbon was transported by the two rivers in the spring and summer months. The different sources and seasonal variations in both fluxes and sources of organic carbon transported by the Yellow River and Changjiang could have an important influence on the biogeochemical cycle and ecosystems in the estuaries and adjacent coastal waters of the East China Sea.
[40] Quirós-Collazos L, Pedrosa-Pàmies R, Sanchez-Vidal A, et al.

Distribution and sources of organic matter in size-fractionated nearshore sediments off the Barcelona City (NW Mediterranean)

[J]. Estuarine Coastal & Shelf Science, 2017, 189:267-280.

DOI      URL      [本文引用: 1]      摘要

We have found a wide range of OC contents, from 0.13 to 8.68%, depending on water depth and sediment particle size. The highest OC concentration was always found in the clay fraction (63μm) that contained terrestrial plant debris. Wave activity, discharge of the Besòs River and the “Espigó de Ginebra” outfall were the main mechanisms controlling the sorting of sediments by their grain size and thus the distribution of OC in the inner shelf off Barcelona. In addition, we observed that the organic matter in clay particles was progressively degraded seawards, probably because these particles remain suspended in the water column much more time compared to those that are heavier and, therefore, they are exposed for longer time periods to oxygenated conditions. Both OC/TN ratios and δ 13 C values found suggest that the organic matter preserved was predominantly land supplied.
[41] Zhang Ling.

A Study on the Distribution, Origin and the Early Diagenesis of Organic Matter on Pearl River Estuary and Adjacent Shelf

[D]. Guangdong: Graduate School of Chinese Academy of Sciences, 2006.

[本文引用: 1]     

[张凌.

珠江口及近海沉积有机质的分布、来源其早期成岩作用研究

[D]. 广东:中国科学院研究生院, 2006.]

[本文引用: 1]     

[42] Cifuentes L A, Coffin R B, Solorzano L, et al.

Isotopic and elemental variations of carbon and nitrogen in a mangrove estuary

[J]. Estuarine Coastal & Shelf Science, 1996, 43(6): 781-800.

DOI      URL      [本文引用: 1]      摘要

Variations in elemental and isotopic ratios of suspended particulate matter (SPM) were investigated in the Guayas River Estuary Ecosystem (GREE) that empties into the Gulf of Guayaquil, Ecuador. Detritus in the system was identified on the basis of extremely high carbon:chlorophyll ratios (>1000). This material had mean C of -26·4±0·3, N of +4·8±0·2, and (C:N)of 14·1±0·9. The isotopic data were comparable to measurements reported for fresh and degrading mangrove leaves, whereas the elemental ratio was comparatively enriched in nitrogen. Isotope measurements of SPM throughout the GREE were more similar to values for riverine material and detritus compared with that for the coastal end-member. Values indicative ofproduced algae, sewage and shrimp pond effluent were only found at selected sites. Bacterial bioassays, which were used to document potential sources of dissolved organic matter in the GREE, were isotopically similar to SPM. This correspondence coupled with the relatively low (C:N)of SPM could be explained by bacterial immobolization of nitrogen onto detritus. Finally, tidal variations of (C:N)and C at a brackish mangrove site were similar in magnitude to spatial variations encountered throughout the GREE. Based on these results, the authors caution that care must be taken when samples are taken for food-web studies in these systems.
[43] Chao Haijuan, Gao Jianhua, Jia Jianjun, et al.

Change of organic matter sources in surface sediments over Changjiang Estuary and its adjacent waters

[J]. Marine Environmental Science, 2017, 36(2): 237-242.

[本文引用: 1]     

[晁海娟, 高建华, 贾建军, .

长江口及其邻近海域表层沉积物的有机质物源变化分析

[J]. 海洋环境科学, 2017, 36(2): 237-242.]

[本文引用: 1]     

[44] Lu Yafang.

Community Dynamics of Phytoplankton in Frequent Redtide Area of East China Sea in Spring

[D]. Fujian: Xiamen University, 2012.

[本文引用: 1]     

[卢亚芳.

东海赤潮高发区春季浮游植物群落结构研究

[D]. 福建:厦门大学, 2012.]

[本文引用: 1]     

[45] Wang Lisha, Shi Xiaoyong, Zhang Chuansong.

Distribution and origins of organic carbon and organic nitrogen in ECS sediments of high frequency HABs areas

[J]. Marine Environmental Science, 2010, 29(2): 165-169.

[本文引用: 1]     

[王丽莎, 石晓勇, 张传松.

东海赤潮高发区沉积物中有机碳、有机氮的分布及其来源

[J]. 海洋环境科学, 2010, 29(2): 165-169.]

DOI      URL      [本文引用: 1]      摘要

对2005年和2006年采集的东海沉积物中有机碳和有机氮的含量进行了测定,结果表明:2005年东海表层沉积物中有机碳含量的变化范围为0.32%~0.82%,平均值为0.65%,而2006年为0.043%~0.78%,平均值为0.32%;2005年表层沉积物中有机氮含量的变化范围为0.047%~0.11%,平均值为0.091%,2006年为0.006%~0.10%,平均值为0.046%.2005年采集的柱状样品中HB08站位有机碳和有机氮含量的变化规律相似,随着深度的增加呈现先降低后又增加,最后又降低的趋势,有机碳含量的变化范围为0.33%~0.57%,平均值为0.43%;有机氮含量的变化范围为0.045%~0.080%.平均值为0.057%;而RB12站位有机碳和有机氮的分布有些差异,有机碳的含量为0.32%~0.52%,有机氮的含量在0.047%~0.072%,2006年表层、2005年采集的HB08和Rb12柱状样中有机碳和有机氮的比值主要在7~10,均说明沉积物中的有机物主要来源于海洋的浮游植物.
[46] Wakeham S G, Canuel E A.

Degradation and Preservation of Organic Matter in Marine Sediments

[M]. Heidelberg: Springer Berlin,2006.

[本文引用: 1]     

[47] Zhang Mingliang, Jiang Meijie, Fu Xiang, et al.

The source of organic matter in the sediment of Laizhou Bay

[J]. Oceanologia et Limnologia Sinica, 2014, 45(4): 741-746.

Magsci      [本文引用: 1]     

[张明亮, 姜美洁, 付翔, .

莱州湾沉积物有机质来源

[J]. 海洋与湖沼, 2014, 45(4): 741-746.]

DOI      URL      Magsci      [本文引用: 1]      摘要

应用C/N、δ<sup><small>13</small></sup>C、δ<sup><small>15</small></sup>N 解析了莱州湾沉积物有机质来源, 发现湾内有机质主要存在海洋、河口浮游植物以及陆地有机质3 种来源。通过C/N、δ<sup><small>13</small></sup>C 定量示踪, 发现海洋浮游植物是湾内沉积物有机质的最主要来源, 相对含量在41.6% - 58.5%之间。河口浮游植物有机质、陆源有机质相对含量波动较大, 分别在3.8% - 43.8%、0 - 53.5%之间。海洋浮游植物有机质在整个海湾都表现出较高含量。近岸河口附近海域往往表现出高含量的河口浮游植物有机质特征, 陆源有机质含量较高区域大都集中在黄河口周围海域, 高河口浮游植物有机质以及高陆源有机质特征在黄河口周围海域均有出现。
[48] Guo Wei, Ye Feng, Xu Shendong, et al.

Seasonal variation in sources and processing of particulate organic carbon in the Pearl River Estuary, South China

[J]. Estuarine Coastal & Shelf Science, 2015, 167: 540-548.

DOI      URL      [本文引用: 2]      摘要

61POC concentration, δ13C and Chlain four seasons along the Pearl River estuary.61Freshwater POC was mainly of aquatic origin, except of detritus soil origin in May.61Estuarine brackish water POC was dominated by in-situ produced OC.61δ13CPOCwas directly related to δ13CDIC, with offset increase in lower or outer PRE.
[49] Bechtel A, Smittenberg R H, Bernasconi S M, et al.

Distribution of branched and isoprenoid tetraether lipids in an oligotrophic and a eutrophic Swiss lake: Insights into sources and GDGT—Based proxies

[J]. Organic Geochemistry, 2010, 41(8): 822-832.

DOI      URL      [本文引用: 2]      摘要

Distributions of isoprenoid (isoGDGT) and branched glycerol dialkyl glycerol tetraethers (brGDGTs) were measured in the water column and sediments of the eutrophic Lake Lugano and the oligotrophic Lake Brienz, Switzerland. Absolute concentrations of isoprenoid, i.e. archaeal GDGTs, were highest in the euphotic zone of both lakes, as well as in sediments deposited at times when lake eutrophication occurred. This indicates that GDGT concentrations may be used as indicators for primary productivity. Both lakes, including the anoxic bottom water of Lake Lugano, are characterised by GDGT distributions typical for group I Crenarchaeota with GDGT-0/crenarchaeol ratios of around 1. Comparison of the distribution of brGDGTs with isoGDGTs and other terrestrial biomarkers throughout the Lake Lugano water column, together with CBT/MBT-derived temperatures that resemble that of the lake, suggest significant in situ production. BIT index values for Lake Brienz sediments (ca. 0.4) were significantly higher than water column values (ca. 0.1), most probably because terrestrial run off events were not captured during water sampling. TEX 86 derived temperatures reflect surface water conditions to within a few degrees, while lower values obtained from deeper water layers suggest a contribution of in situ produced isoGDGTs. For both lake sediments, TEX 86-derived temperatures could be matched reasonably with mean annual lake surface water temperature variation, albeit with a larger offset for Lake Lugano. This suggests that absolute temperatures can only be reconstructed from lake sediments for which a local calibration is known.
[50] Powers L A, Werne J P, Johnson T C, et al.

Crenarchaeotal membrane lipids in lake sediments: A new paleotemperature proxy for continental paleoclimate reconstruction?

[J]. Geology, 2004, 32(7): 613-616.

DOI      URL      [本文引用: 2]      摘要

Paleoclimate studies of continental environments have been hampered by the lack of an independent paleotemperature proxy. A novel sea-surface temperature proxy has been proposed for marine systems based on membrane lipids of marine crenarchaeota (the TEX etraether index of tetraethers with 86 carbon atoms). Analysis of archaeal membrane lipids in core-top sediments from a diverse suite of lacustrine systems suggests the ubiquitous occurrence of low-temperature crenarchaeota in lake systems as well. Application of the TEXproxy in these lacustrine systems indicates that it is valid in lake environments, and the calibration of TEXin lacustrine systems is similar to that in the marine environment. This proxy will provide an independent continental paleotemperature tool that will allow paleoclimatologists to address fundamental questions about temperature variability in continental environments and its relationship to climate change.
[51] Weijers J W H, Schouten S, Spaargaren O C, et al.

Occurrence and distribution of tetraether membrane lipids in soils: Implications for the use of the TEX86 proxy and the BIT index

[J]. Organic Geochemistry, 2006, 37(12): 1 680-1 693.

DOI      URL      [本文引用: 1]      摘要

A diverse collection of globally distributed soil samples was analyzed for its glycerol dialkyl glycerol tetraether (GDGT) membrane lipid content. Branched GDGTs, derived from anaerobic soil bacteria, were the most dominant and were found in all soils. Isoprenoid GDGTs, membrane lipids of Archaea, were also present, although in considerably lower concentration. Crenarchaeol, a specific isoprenoid membrane lipid of the non-thermophilic Crenarchaeota, was also regularly detected and its abundance might be related to soil pH. The detection of crenarchaeol in nearly all of the samples is the first report of this type of GDGT membrane lipid in soils and is in agreement with molecular ecological studies, confirming the widespread occurrence of non-thermophilic Crenarchaeota in the terrestrial realm. The fluvial transport of crenarchaeol and other isoprenoid GDGTs to marine and lacustrine environments could possibly bias the BIT index, a ratio between branched GDGTs and crenarchaeol used to determine relative terrestrial organic matter (TOM) input. However, as crenarchaeol in soils is only present in low concentration compared to branched GDGTs, no large effect is expected for the BIT index. The fluvial input of terrestrially derived isoprenoid GDGTs could also bias the TEX 86, a proxy used to determine palaeo surface temperatures in marine and lacustrine settings and based on the ratio of cyclopentane-containing isoprenoid GDGTs in marine and lacustrine Crenarchaeota. Indeed, it is shown that a substantial bias in TEX 86-reconstructed sea and lake surface temperatures can occur if TOM input is high, e.g. near large river outflows.
[52] Li Zhongqiao, Peterse F, Wu Ying, et al.

Sources of organic matter in Changjiang (Yangtze River) bed sediments: Preliminary insights from organic geochemical proxies

[J]. Organic Geochemistry, 2015, 85: 11-21.

DOI      URL      [本文引用: 2]      摘要

Insight into the content and composition of organic carbon (OC) in river systems contributes to our understanding of the global carbon cycle. The Changjiang (Yangtze River) plays a significant role in global carbon and hydrological cycles, as it is an important supplier of sediment, nutrients and OC to the East China Sea. To provide a preliminary insight into the source of OC transported by the Changjiang, we analyzed bulk (grain size, organic carbon content, 13C), and molecular (lignin phenols, branched and isoprenoid GDGTs) characteristics of organic matter in bed sediments at eight locations along the river. The 13C values and lignin phenol composition indicate that the OC originates from a mixture of primarily soils and plants. Comparison between branched GDGT (br GDGT) distributions in riverbed sediments and those in the different soil types in the drainage basin indicate that the br GDGT signal in the upper reaches is largely derived from soils from the Qinghai-Tibet Plateau. Downstream changes in br GDGT distributions can be linked to subsequent input of local soil material. The observed variation in br GDGT composition along the river implies that a portion of the OC may be oxidized or replaced by the local input during transit. Although the relationship between 13C and lignin phenol composition indicates that the contribution of phytoplankton is limited, comparison of GDGT ratios (GDGT-0:crenarchaeol, iso GDGTs:br GDGTs, BIT index) for the sediments and surrounding soils indicates that at least part of the iso GDGTs has an aquatic origin. Overall, the downstream evolution of br GDGTs in the Changjiang implies that their use as paleoclimate proxy in downcore applications will likely yield a local, rather than a basin-integrated continental climate record.
[53] Park Y-H, Yamamoto M, Nam S-I, et al.

Distribution, source and transportation of glycerol dialkyl glycerol tetraethers in surface sediments from the western Arctic Ocean and the northern Bering Sea

[J]. Marine Chemistry, 2014, 165: 10-24.

DOI      URL      [本文引用: 1]      摘要

61Isoprenoid GDGTs are abundant on the outer shelf and slope of the Chukchi Sea.61TEX86- and TEX86L are not consistent with sea surface temperatures.61Branched GDGTs originated from the water column and the terrestrial realm.
[54] Peterse F, Eglinton T I.

Grain size associations of branched tetraether lipids in soils and riverbank sediments: Influence of Hydrodynamic sorting processes

[J]. Frontiers in Earth Science, 2017, 5: 49. DOI: 10.3389/feart.2017.00049.

URL      [本文引用: 1]     

[55] Ebersbach F, Goldenstein N, Iversen M, et al.

Mechanisms for the export of archaeal lipids down the water column in the upwelling area off Cape Blanc, North-West Africa

[C]∥EGU General Assembly Conference. EGU General Assembly Conference Abstracts, 2016.

[本文引用: 1]     

[56] Ingalls A E, Huguet C, Truxal L T.

Distribution of intact and core membrane lipids of archaeal glycerol dialkyl glycerol tetraethers among size-fractionated particulate organic matter in hood canal, puget sound

[J]. Applied and Environmental Microbiology, 2012, 78(5): 1 480-1 490.

DOI      URL      PMID      [本文引用: 1]      摘要

Abstract There is great interest in the membrane lipids of archaea (glycerol dialkyl glycerol tetraethers [GDGTs]) as tracers of archaeal biomass because of their utility as paleoproxies and because of the biogeochemical importance of archaea. While core GDGTs (formed by hydrolysis of polar head groups of intact GDGTs after cell death) are appropriate for paleostudies, they have also been used to trace archaeal populations. Also, despite the small size (0.2 by 0.7 m) of cultivated marine archaea, 0.7- m glass-fiber filters (GFFs) are typically used to collect GDGTs from natural waters. We quantified both core and intact GDGTs in free-living (0.2- to 0.7- m), suspended (0.7- to 60- m), and aggregate (>60- m) particle size fractions in Puget Sound (Washington State). On average, the free-living fraction contained 36% of total GDGTs, 90% of which were intact. The intermediate-size fraction contained 62% of GDGTs, and 29% of these were intact. The aggregate fraction contained 2% of the total GDGT pool, and 29% of these were intact. Our results demonstrate that intact GDGTs are largely in the free-living fraction. Because only intact GDGTs are present in living cells, protocols that target this size fraction and analyze the intact GDGT pool are necessary to track living populations in marine waters. Core GDGT enrichment in larger-size fractions indicates that archaeal biomass may quickly become attached or entrained in particles once the archaea are dead or dying. While the concentrations of the two pools were generally not correlated, the similar sizes of the core and intact GDGT pools suggest that core GDGTs are removed from the water column on timescales similar to those of cell replication, on timescales of days to weeks.
[57] Ge Tiantian, Li Dawei, Zhao Zongshan, et al.

Multi-proxy records of terrestrial and marine organic matter sources in the mud area southwest off Cheju Island over the last 100 years

[J]. Periodical of Ocean University of China, 2013, 43(2): 40-47.

[本文引用: 2]     

[葛田田, 李大伟, 赵宗山, .

过去一百年济州岛西南泥质区有机质来源变化的多参数指标研究

[J]. 中国海洋大学学报:自然科学版, 2013, 43(2):40-47.]

[本文引用: 2]     

[58] Wang Jinpeng, Yao Peng, Meng Jia, et al.

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

[J]. Acta Oceanological Sinica, 2015, 37(6): 41-57.

[本文引用: 1]     

[王金鹏, 姚鹏, 孟佳, .

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

[J]. 海洋学报, 2015, 37(6): 41-57.]

[本文引用: 1]     

[59] Cai Jingong, Xu Jinli, Feng Xiaoping, et al.

The characteristic of palynofacies of surface sediments collected from the Changjiang Estuary and its significance in carbon cycle

[J]. Earth Science Frontiers, 2011, 18(6): 143-149.

[本文引用: 2]     

[蔡进功, 徐金鲤, 冯晓萍, .

长江口表层沉积物孢粉相特征及其在碳循环中的意义

[J]. 地学前缘, 2011, 18(6): 143-149.]

URL      [本文引用: 2]      摘要

选自长江口F2—F5站位的4个表层沉积物及其粒度分级(1~8Φ)样品,经过孢粉相和热解检测,探讨有机质特征及其在碳循环中的命运。 分级样品的孢粉相主要由木质组织、丝炭和黑团块组成,显示陆地输入有机质的贡献巨大。样品分级后,孢粉相面貌发生显著变化。细粒的8Φ中无定形为主,其他粒级(2~7Φ)中主要由结构有机质组成。细粒的8Φ中具有高HI、高S2和低Tmax值的特点,表明来源于水生生物;而其他粒级(2~7Φ)有机质显示了高等植物来源和充分氧化降解的特性。在远离河口的F4和F5站位,细粒的8Φ中无定形有机质对TOC贡献约近70%;在河口附近F2和F3站位,粗粒的(2~7Φ)中颗粒有机质聚集,TOC分配比较均衡。细粒的8Φ中无定形有机质,受粘土矿物的保护可有效抵御微生物及氧化降解,能迅速地絮凝和沉降,缩短了从生物圈、水圈到岩石圈的进程,致使碳循环周期延长;而粗粒的(2~7Φ)中陆地输入的颗粒有机质,已历经充分的氧化降解,可以长期保存在沉积物中,碳循环周期最长。因此,关注沉积物中有机质与粘土矿物的相互关系以及对碳循环周期的影响,这可能是开启 知碳汇之谜的一把"金钥匙"。
[60] Arndt S, Jørgensen B B, Larowe D E, et al.

Quantifying the degradation of organic matter in marine sediments: A review and synthesis

[J]. Earth-Science Reviews, 2013, 123(4): 53-86.

DOI      URL      [本文引用: 1]      摘要

Quantifying the rates of biogeochemical processes in marine sediments is essential for understanding global element cycles and climate change. Because organic matter degradation is the engine behind benthic dynamics, deciphering the impact that various forces have on this process is central to determining the evolution of the Earth system. Therefore, recent developments in the quantitative modeling of organic matter degradation in marine sediments are critically reviewed. The first part of the review synthesizes the main chemical, biological and physical factors that control organic matter degradation in sediments while the second part provides a general review of the mathematical formulations used to model these processes and the third part evaluates their application over different spatial and temporal scales. Key transport mechanisms in sedimentary environments are summarized and the mathematical formulation of the organic matter degradation rate law is described in detail. The roles of enzyme kinetics, bioenergetics, temperature and biomass growth in particular are highlighted. Alternative model approaches that quantify the degradation rate constant are also critically compared. In the third part of the review, the capability of different model approaches to extrapolate organic matter degradation rates over a broad range of temporal and spatial scales is assessed. In addition, the structure, functions and parameterization of more than 250 published models of organic matter degradation in marine sediments are analyzed. The large range of published model parameters illustrates the complex nature of organic matter dynamics, and, thus, the limited transferability of these parameters from one site to another. Compiled model parameters do not reveal a statistically significant correlation with single environmental characteristics such as water depth, deposition rate or organic matter flux. The lack of a generic framework that allows for model parameters to be constrained in data-poor areas seriously limits the quantification of organic matter degradation on a global scale. Therefore, we explore regional patterns that emerge from the compiled more than 250 organic matter rate constants and critically discuss them in their environmental context. This review provides an interdisciplinary view on organic matter degradation in marine sediments. It contributes to an improved understanding of global patterns in benthic organic matter degradation, and helps identify outstanding questions and future directions in the modeling of organic matter degradation in marine sediments.

/