Organic Geochemical Studies in the Southern Ocean

本研究项目是美国联合全球海洋通量研究（JGOFS）南大洋项目的一部分，旨在：(1)更好地了解南大洋有机和无机碳通量，(2)确定调节这些通量的大小和变化的物理、生态和生物地球化学因素和过程，以及(3)将这些通量置于当代全球碳循环的背景下。这项工作是“南大洋实验”（Southern Ocean Experiment）中44个合作项目之一。南大洋实验是在南极极地锋区（Antarctic Polar fronzone）以南进行的一项为期三年的努力，旨在追踪碳从空气-海洋界面通过整个水柱进入底部沉积物的有机和无机途径的流动。该实验将利用RVIB纳撒尼尔B.帕尔默和R/V汤普森。这一组成部分涉及对南大洋水柱和表层沉积物中有机质循环的合作研究。这项工作的主要目标是：(1)确定南大洋内有机物质的组成和通量如何在区域和季节上发生变化；(2)将这些变化与间断的有机输入及其硅质基质的生物处理过程联系起来；(3)通过水柱跟踪浮游生物遗骸向下的成岩命运，进入下面的沉积物，特别强调反映基质质量（新鲜度）的生化趋势；(4)通过对散装捕集器和沉积物样品的碳-13分析，全面解释降解各阶段的总有机质。船上的工作包括在拟议的研究样带沿线的几个地点收集水柱内和底层沉积物中的悬浮和降雨颗粒物质。悬浮颗粒将通过浮游生物网拖网和地表水的大容量过滤来收集。下沉的颗粒将被模块式沉积物捕集器收集，这些捕集器一组部署4个。将设计单独的捕集器，有选择地收集下沉的颗粒，并在不损失样品或杀菌剂的情况下拒绝游动的浮游动物。每个阵列上的四个捕集器中的两个将安装12管次采样旋转盘，以研究短期变化。收集的捕集器和沉积物核心样品将分析其基本的生化组成部分，如碳水化合物、氨基酸、脂类、木质素和色素。它们构成了上层水柱中产生的大部分有机物，也是埋藏在沉积物中的物质的重要组成部分。在分子水平上，它们可以提供关于有机物的来源及其在深海中的分解，以及生物物质转移到沉积物的途径的明确信息。这些数据将与先前JGOFS实验中获得的信息相结合，以产生海洋中颗粒物质有机化学的全球图景。＊＊＊

9531763 Hedges This research project is part of the US Joint Global Ocean Flux Study (JGOFS) Southern Ocean Program aimed at (1) a better understanding of the fluxes of carbon, both organic and inorganic, in the Southern Ocean, (2) identifying the physical, ecological and biogeochemical factors and processes which regulate the magnitude and variability of these fluxes, and (3) placing these fluxes into the context of the contemporary global carbon cycle. This work is one of forty-four projects that are collaborating in the Southern Ocean Experiment, a three-year effort south of the Antarctic Polar Frontal Zone to track the flow of carbon through its organic and inorganic pathways from the air-ocean interface through the entire water column into the bottom sediment. The experiment will make use of the RVIB Nathaniel B. Palmer and the R/V Thompson. This component concerns a cooperative study of organic matter cycling in the water column and in the surficial sediments of the Southern Ocean. The main goals of the effort are: (1) to determine how the composition and fluxes of organic material vary regionally and seasonally within the Southern Ocean, (2) to relate these variations to biological processing of the punctuated organic input and its siliceous matrix, (3) to follow the downward diagenetic fate of planktonic remains through the water column and into the underlying sediments, with special emphasis on biochemical trends reflecting substrate quality (freshness), and (4) to holistically account for total organic matter at all stages of degradation by carbon-13 analysis of bulk trap and sediment samples. The shipboard work involves collecting suspended and raining particulate material within the water column and from the underlying sediment at several sites along the proposed study transect. Suspended particles will be collected both by plankton net tows and high volume filtration of surface water. Sinking particles will be collected w ith modular sediment traps deployed in arrays of four. Individual traps will be designed to selectively collect sinking particles and reject swimming zooplankton without loss of sample or biocide. Two of the four traps on each array will be fitted with 12-tube subsampling carousels to study shorter term variations. The collected trap and sediment core samples will be analyzed for their basic biochemical building blocks, such as carbohydrates, amino acids, lipids, lignins, and pigments. These make up the bulk of the organic matter produced in the upper water column and are an important fraction of the material buried in the sediment. At the molecular level they can provide unequivocal information on the sources of organic matter and its decomposition at depth, and on the pathways by which biogenic material is transferred to the sediment. These data will be combined with information obtained during prior JGOFS experiments to produce a global picture of the organic chemistry of particulate matter in the ocean. ***