Particle Flux and Remineralization at Hawaii Ocean Time-Series Station ALOHA: Development of a New Estimation Method Based on 230Th and 231Pa

夏威夷海洋时间序列站 ALOHA 的粒子通量和再矿化：开发基于 230Th 和 231Pa 的新估计方法

• 批准号: 0117922
• 负责人: Roger Francois
• 金额: $ 38.91万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0117922&HistoricalAwards=false
• 关键词: Particle; Flux; Remineralization; Hawaii; Ocean

ABSTRACTOCE-0117922In this project, researchers at the Woods Hole Oceanographic Institution will develop a technique independent of sediment traps for determining particle flux throughout the oceanic water column. It is based on the known rate of production of 230Th and 231Pa from decay of U isotopes dissolved in seawater and is similar in concept to the use of 234Th to determine export flux from the euphotic zone. Particles of various size ranges will be sampled by large- volume (1000-2000 liters), in-situ filtration and analyzed for the two radionuclides and for their major components (organic matter, carbonate, opal, aluminosilicate). The whole water column will be sampled, but a major emphasis will be on remineralization of organic matter in the mesopelagic zone (~150 - 1500m), where there is a large decrease of the flux with depth but where direct measurement of the flux with sediment traps is difficult and subject to large errors. The Hawaii Ocean Time-series (HOT) Station ALOHA is the site chosen for this initial study because it is remote from the complicating effects of ocean margins and because of the logistical ease and the supporting data provided by the ongoing time-series program. The proposed method is made feasible by the recent development of high-sensitivity analytical methods for measurement of 230Th and 231Pa in small samples by inductively-coupled plasma mass spectrometry (ICP-MS). If the concept proves in this project to be successful, the method could be applied to other oceanic areas and could be extended to a variety of specific elements and compounds.

在这个项目中，伍兹霍尔海洋研究所的研究人员将开发一种独立于沉积物捕集器的技术，用于测定整个海洋水柱的颗粒通量。它是根据溶解在海水中的U同位素衰变产生230和231Pa的已知速率计算的，在概念上类似于使用234来确定从透光带输出的通量。将对各种尺寸范围的颗粒进行大体积取样（1000-2000升），现场过滤并分析两种放射性核素及其主要成分（有机物、碳酸盐、蛋白石、铝硅酸盐）。将对整个水柱进行采样，但主要重点将放在中远洋带（~150 - 1500m）有机质的再矿化作用上，那里的通量随深度大大减少，但用沉积物捕集器直接测量通量是困难的，而且误差很大。夏威夷海洋时间序列（HOT）站ALOHA被选为这项初步研究的地点，因为它远离海洋边缘的复杂影响，而且由于后勤便利和正在进行的时间序列项目提供的支持数据。最近电感耦合等离子体质谱（ICP-MS）高灵敏度分析方法在小样本中测量230Th和231Pa的发展使所提出的方法变得可行。如果这一概念在本项目中证明是成功的，该方法可应用于其他海洋地区，并可扩展到各种特定元素和化合物。