Thorium Isotopes as Indicators of Export Flux and Particle Dynamics in the Southern Ocean: Joint Global Ocean Flux Study

钍同位素作为南大洋输出通量和粒子动力学的指标：全球海洋通量联合研究

• 批准号: 9612761
• 负责人: J Kirk Cochran
• 金额: $ 28.12万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-08-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9612761&HistoricalAwards=false
• 关键词: Thorium; Isotopes; Indicators; Export; Flux

961-2761 Cochran 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 on six process cruises between Oct.-Nov., 1996, and March 1998. This component focuses on the spatial and temporal variations in the distributions and particulate fluxes of thorium isotopes (thorium-234 and thorium-228). These isotopes serve as ocean tracers that yield fundamental information about the rates of biogeochemical processes that govern the production and fate of biogenic particles in the oceanic water column. Measurements of thorium-234 will be made at sea by beta and gamma-counting; measurements of thorium-228 will be made ashore by alpha- spectrometry. The data will be interpreted within the context of biological rate measurements and other data to be collected during the study and will be used to provide estimates of export fluxes of organic matter, carbonate, and silica from the euphotic zone; to quantify transformation processes such as aggregation and disaggregation in the water column; and to test biogeochemical models. Thorium is a particularly useful tracer in this context because its mode of production is well known; it is taken up quickly by biogenic particles, and it s concentration can be measured quite precisely. The removal of thorium by falling particles can therefore be determined, and the inverse problem of inferring the integrated mass of falling particles (the particulate carbon flux) may be solved. *** .

小行星961-2761 该研究项目是美国联合全球海洋通量研究（JGOFS）南大洋计划的一部分，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，（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中合作的44个项目之一，南大洋实验是一项为期三年的南极极地锋区南部的努力，旨在跟踪碳通过其有机和无机途径从空气-海洋界面通过整个水柱进入底部沉积物的流动。 实验将使用RVI B Nathaniel B。帕尔默和R/V汤普森在10月至12月期间进行了六次工艺巡航。11月，1996年和1998年3月。 本部分侧重于钍同位素（钍-234和钍-228）的分布和微粒通量的时空变化。 这些同位素作为海洋示踪剂，产生有关海洋地球化学过程速率的基本信息，这些过程控制着海洋水柱中生物颗粒的产生和归宿。 钍-234的测量将在海上用β和γ计数法进行;钍-228的测量将在岸上用α光谱法进行。 这些数据将在生物速率测量和研究期间收集的其他数据的范围内进行解释，并将用于提供有机物、碳酸盐和二氧化硅从透光层输出通量的估计数;量化水柱中的聚集和解聚等转化过程;并测试生物地球化学模型。 钍在这方面是一种特别有用的示踪剂，因为它的生产方式是众所周知的;它被生物颗粒迅速吸收，并且它的浓度可以非常精确地测量。 因此，可以确定下落颗粒对钍的去除，并且可以解决推断下落颗粒的积分质量（颗粒碳通量）的逆问题。 *** .