Biocomplexity: Collaborative Research: Oceanic N2 Fixation and Global Climate

生物复杂性：合作研究：海洋固氮与全球气候

• 批准号: 0323332
• 负责人: Scott Doney
• 金额: $ 23.23万
• 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: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0323332&HistoricalAwards=false
• 关键词: Biocomplexity; Collaborative; Research; Oceanic; N2

Oceanic N2 fixation has recently been identified as a significant part of the oceanic nitrogen (N) cycle and may directly influence the sequestration of atmospheric C02 in the oceans by providing a new source of N to the upper water column. The prokaryotic microorganisms that convert N2 gas to reactive N are an unique subcomponent of planktonic ecosystems and exhibit a variety of complex dynamics including the formation of microbial consortia and symbioses and, at times, massive blooms. Accumulating evidence indicates that iron (Fe) availability may be a key controlling factor for these planktonic marine diazotrophs. The primary pathway of Fe delivery to the upper oceans is through dust deposition.N2 fixers may therefore be directly involved in global feedbacks with the climate system and these feedbacks may also exhibit complex dynamics on many different time?scales. The hypothesized feedback mechanisms will have the following component parts: The rate Of N2 fixation in the world's oceans can have an impact on the concentration of the greenhouse gas, carbon dioxide (C02), in the atmosphere on time?scales of decades (variability in surface biogeochemistry) to millennia (changes in the total N03 ? stock from the balance of N2 fixation and denitrification). C02 concentrations in the atmosphere influence the climate. The climate system, in turn, can influence the rate Of N2 fixation in the oceans by controlling the supply of Fe on dust and by influencing the stratification of the upper ocean. Humans also have a direct role in the current manifestation of this feedback cycle by their influence on dust production, through agriculture at the margins of deserts, and by our own production Of C02 into the atmosphere. The circular nature of these influences can lead to a feedback system, particularly on longer timescales.This project involves studying each of the components of this system and then modeling the hypothesized feedback processes. Because of the interaction of the various parts of this system, keyed around the unique behavior and biogeochemistry of the prokaryotic microorganisms that can fix N2, this feedback loop should exhibit complex behaviors on a variety of time?scales. The research will be conducted through a targeted series of experiments and field observations to understand and parameterize each of the pieces of this global process including the direct control of marine N2 fixation by dust deposition. This understanding will then feed a modeling process that examines the complex dynamics of this system on time?scales of years to millennia. The modeling process will be evaluated by comparison with data on the time?dependent behavior of ocean biogeochemistry as available from ocean time?series studies and sediment cores.

海洋N2固定最近已被确定为海洋氮（N）周期的重要部分，并通过为上水柱提供新的N来源，可能直接影响海洋中大气C02的隔离。将N2气体转换为反应性n的原用微生物是浮游生物生态系统的独特子组成部分，并且表现出各种复杂的动力学，包括形成微生物联盟和共生性，有时甚至是大量的开花。积累的证据表明，铁（FE）的可用性可能是这些浮游生物重18zotrophs的关键控制因素。因此，向高海洋传递的主要途径是通过尘埃沉积。因此，N2固定器可能直接参与与气候系统的全球反馈，这些反馈也可能在许多不同的时间范围内表现出复杂的动力学。假设的反馈机制将具有以下组成部分：世界海洋中的N2固定速率可能会影响大气中的温室气体，二氧化碳二氧化碳（C02）的浓度，在时间上，数十年来？（表面生物地球化学的变化）（表面生物地球化学的变化）对数百万年内（数百万）den deN（n03 dectiation n03？fidit fiftiation five five fift fiftiation and fivation and n2？大气中的C02浓度会影响气候。反过来，气候系统可以通过控制灰尘上的Fe供应并影响上海的分层来影响海洋中N2固定的速度。人类还通过对尘埃生产的影响，通过在沙漠的边缘以及我们自己的C02生产到大气中的农业，在此反馈周期的当前表现中发挥了直接作用。这些影响的循环性质可能导致反馈系统，尤其是在较长的时间尺度上。该项目涉及研究该系统的每个组件，然后对假设的反馈过程进行建模。由于该系统的各个部分的相互作用，围绕可以修复N2的原核生物的独特行为和生物地球化学的关键，因此此反馈回路应在各种时间范围内表现出复杂的行为。这项研究将通过针对性的一系列实验和现场观测来进行，以了解和参数化全局过程的每个部分，包括通过尘埃沉积对海洋N2固定的直接控制。然后，这种理解将为建模过程提供一个时间，该过程会按时检查该系统的复杂动态？几年到千年。将通过与时间的数据进行比较来评估建模过程？海洋生物地球化学的依赖性行为是海洋时代的串联研究和沉积物核心。