Nature and Transformations of Particulate Carbohydrates in the Oceanic Water Column

碳水化合物是所有海洋生物，特别是浮游植物的主要有机成分，因此这些物质构成了海洋颗粒有机物(POM)的很大部分。然而，与其他重要的生物分子，如脂质和蛋白质相比，令人惊讶的是，海洋POM中的碳水化合物却很少受到关注。因此，本研究对以下假设进行了验证：1.在水柱中颗粒下降的过程中，储藏碳水化合物优先丢失，而残留物中的结构多糖相对增加。后者可作为生物标志物，前者的损失可用来估计POM随深度变化的能量潜力(热值)和降解速率；2.藻类是海洋碳水化合物的主要来源，但在靠近陆地的地方，陆源来源可能成为当地的重要来源。这些输入可以根据它们的碳水化合物组成来区分；3.由于颗粒下降过程中的微生物降解，形成了新的多糖。这些新的糖在很大程度上与原始材料的组成不同，因此可以用来估计微生物降解POM的程度。这项研究将主要基于对作为Vertex计划一部分部署的沉积物捕集器样本的分析。分析技术将包括使用选择性解聚结合高分辨率GC和HPLC。放在Vertex计划的背景下，特别是在蛋白质、脂类和微生物活动方面所做的工作，拟议的碳水化合物研究将大大有助于我们理解影响WATR柱中有机物质通量和成岩作用的过程。

Carbohydrates represent a major organic component of all marine organisms, especially phytoplankton, and thus these substances constitute a large fraction of oceanic particulate organic matter (POM). However, in comparison to other important groups of biomolecules, eg, lipids and proteins, surprisingly little attention has been paid to carbohydrates in oceanic POM. Therefore, a study to test the following hypotheses: 1. During descent of particles in the water column, storage carbohydrates are preferentially lost while structural polysaccharides are relatively enhanced in the residue. The latter compounds can be used as biomarkers, while loss of the former may be used to estimate the energy potential (caloric value) and rate of degradation of POM with depth; 2. Algae are the major sources of carbohydrates in the sea, but close to land, terrigenous sources may become locally important. These inputs can be differentiated on the basis of their carbohydrate compositions; 3. As a result of microbial degradation during descent of particles, new polysaccharides are formed. These new saccharides are to a large degree compositionally distinct from the original materials and thus may be used to estimate the degree of microbial degradation POM. The study will be based largely on analyses of samples from sediment traps deployed as part of the VERTEX Program. Analytical techniques will include the use of selective depolymerizations coupled with high resolution GC and HPLC. When put in the context of the VERTEX Program, especially work being done on proteins, lipids, and microbial activity, the proposed study of carbohydrates should contribute significantly towards our understanding of the processes affecting fluxes of organic material and diagenesis in the watr column.