Linking high latitude nutrient supply to export productivity and nitrogen cycling in the tropical Pacific across the Plio-Pleistocene

将高纬度养分供应与上里欧-更新世热带太平洋的出口生产力和氮循环联系起来

• 批准号: 1060779
• 负责人: Rebecca Robinson
• 金额: $ 36.31万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1060779&HistoricalAwards=false
• 关键词: Linking; latitude; nutrient; supply; export; Linking; latitude; nutrient; supply; export

Recent work has demonstrated the importance of nutrient supply in driving export productivity events in the eastern equatorial Pacific and stimulating denitrification downstream. However, this view is limited to the last 30,000 years. On orbital timescales, variations likely relate to changes in overturning rate in the high latitude Southern Ocean. On million-year timescales, it is hypothesized that the shoaling of the ventilated thermocline, due to global cooling, strengthened the connection between high and low latitude biogeochemistry. This study, led by a researcher from the University of Rhode Island, seeks to understand how variations in nutrient supply, export productivity, oxygen demand, and water column denitification relate to large scale changes in ocean circulation on long timescales. Longer records are essential in order to evaluate the significance of high latitude nutrient supply in driving low latitude biogeochemical shifts, and will provide insight into both the cyclic changes occurring on orbital timescales and longer timescale shifts. The study focuses on two key questions: 1) What is the role of nutrient supply from high latitudes in driving documented episodes of high productivity in the eastern equatorial Pacific?, and 2) What is the role of enhanced export and oxygen demand in modulating water column denitrification in the eastern tropical Pacific? The study builds on available downcore data and add nitrogen isotope and export productivity records from the Southern Ocean and tropical Pacific across the last 3 million years. Records from a series of sites across the tropical Pacific will result in a stacked record of denitrification changes and an estimate of nutrient supply changes in the eastern equatorial Pacific. The Southern Ocean records will be used to estimate preformed nutrient concentrations at the origin of mode waters. The new records will be incorporated into a larger international collaboration that aims to develop a coherent picture of how climate-driven circulation changes in the Plio- Pleistocene impact the global cycling of nitrogen and carbon. This project also represents a first step toward developing a complete Cenozoic history of nutrient cycling and export productivity in the eastern equatorial Pacific.Broader impacts include education and training of a graduate student, public outreach activities, and international collaboration with a French scientist.

最近的工作表明，养分供应在驱动东部赤道太平洋的出口生产力事件中的重要性以及下游刺激反硝化的重要性。但是，这种观点仅限于过去30，000年。在轨道时尺度上，变化可能与南大洋高纬度的倾斜率变化有关。在百万年的时间尺度上，可以假设，由于全球冷却，通风热线的浅滩加强了高纬度生物地球化学之间的联系。这项研究由罗德岛大学的一名研究人员领导，试图了解养分供应，出口生产率，氧气需求和水柱的变化如何与长时间尺度海洋循环的大规模变化有关。更长的记录对于评估高纬度养分供应在驱动低纬度生物地球化学转移方面的重要性至关重要，并将洞悉轨道时标和更长的时间尺度变化的环环变化。该研究的重点是两个关键问题：1）高纬度地区的营养供应在驱动东部赤道太平洋的高生产率发作中的作用是什么？该研究基于可用的下侧数据，并在过去300万年中添加了来自南洋和热带太平洋的氮同位素和出口生产力记录。来自热带太平洋地区一系列地点的记录将导致堆积的硝化变化记录和东部赤道太平洋养分供应变化的估计。南大洋的记录将用于估计模式水域起源的预先形成的养分浓度。新记录将纳入更大的国际合作中，旨在制定一致的图片，即气候驱动的循环如何在更新世中影响全球氮和碳的全球循环。该项目还代表着在东部赤道太平洋地区开发养分循环和出口生产力的完整的新生代历史的第一步。Broader的影响包括教育和培训研究生，公共外展活动，以及与法国科学家的国际合作。