Seasonal and Spatial Variations in the Flux of Particulate Organic Carbon Derived from Thorium-234 in the U.S. JGOFS Southern Ocean Process Study

9530861 Buessler本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的通量，(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。这项工作是在南大洋实验中合作的44个项目之一，这是一项为期三年的努力，位于南极极地前锋地带以南，旨在追踪碳通过有机和无机路径从空气-海洋界面通过整个水柱进入海底沉积物的流动。该实验将利用RVIB纳撒尼尔·B·帕尔默和R/V汤普森。这一构成部分的目标是提供与了解生物和物理过程有关的空间和时间尺度上的上层海洋颗粒有机碳输出通量的定量估计。方法是测量半衰期为24.1天的颗粒反应性示踪剂--钍-234的浓度及其与颗粒有机碳(POC)和颗粒有机氮(PON)的比率，以得出适当的出口数据。研究活动包括在南极极地前缘地带跨越季节性生产周期的游轮上收集钍-234和POC样品。研究结果将用于限制上层海洋的下沉通量，并在低生产力和高生产力的季节过渡期间推导物理梯度(即锋面)上的生产和出口之间的关系。还将审查这些利率估计值对模型假设和数据质量的敏感性。***

9530861 Buessler 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. The objective of this component is to provide a quantitative estimate of upper ocean export fluxes of particulate organic carbon on spatial and temporal scales relevant to understanding biological and physical processes. The approach is to measure the concentration of thorium-234, a particle reactive tracer with a half-life of 24.1 days, and its ratio to particulate organic carbon (POC) and particulate organic nitrogen (PON) in order to derive the appropriate export data. The research activities include the collection of thorium-234 and POC samples on cruises spanning the seasonal production cycle in the Antarctic Polar Front Zone. The results will be used to constrain the upper ocean sinking fluxes and to derive relationships between production and export across physical gradients (i.e. fronts) during seasonal transitions between low and high productivity. The sensitivity of these rate estimates to model assumptions and data quality will also be examined. ***