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

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

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。

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） , sta- ble isotopes （δ1c3C） 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 pa- rameter 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.