BIOCOMPLEXITY: Collaborative Research: Oceanic N2 fixation and Global climate

生物复杂性：合作研究：海洋 N2 固定和全球气候

• 批准号: 9981662
• 负责人: Edward Carpenter
• 金额: $ 20万
• 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: 2000
• 资助国家: 美国
• 起止时间: 2000-01-01 至 2001-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9981662&HistoricalAwards=false
• 关键词: BIOCOMPLEXITY; Collaborative; Research; Oceanic; N2

Oceanic nitrogen (N2) fixation has recently been identified as a significant part of theoceanic nitrogen (N) cycle and may directly influence the sequestration of atmospheric CO2 inthe oceans by providing a new source of N to the upper water column. The prokaryoticmicroorganisms that convert N2 gas to reactive N are an unique subcomponent of planktonicecosystems and exhibit a variety of complex dynamics including the formation of microbialconsortia and symbioses and, at times, massive blooms. Accumulating evidence indicates thatiron (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 systemand 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 N2fixation in the world's oceans can have an impact on the concentration of the greenhouse gas,carbon dioxide (CO2), in the atmosphere on time-scales of decades (variability in surfacebiogeochemistry) to millennia (changes in the total NO3 - stock from the balance of N2 fixationand denitrification). CO2 concentrations in the atmosphere influence the climate. The climatesystem, in turn, can influence the rate of N2 fixation in the oceans by controlling the supply of Feon dust and by influencing the stratification of the upper ocean. Humans also have a direct rolein the current manifestation of this feedback cycle by their influence on dust production, throughagriculture at the margins of deserts, and by our own production of CO2 into the atmosphere.The circular nature of these influences can lead to a feedback system, particularly on longer time-scales.This collaborative and interdisciplinary group of investigators, led by Dr. Anthony Michaels, will study each of the components of this system and then to model 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. In this research, we will conduct 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

海洋固氮是海洋氮循环的重要组成部分，通过为上层水体提供新的氮源，直接影响海洋大气CO2的封存。将N2气体转化为活性N的原核微生物是亚生态系统的独特亚组分，并表现出各种复杂的动力学，包括微生物聚生体和共生体的形成，有时，大量的水华。越来越多的证据表明，铁（Fe）的有效性可能是这些海洋固氮生物的关键控制因素，铁向上层海洋的主要输送途径是通过尘埃沉积，因此，N2固定生物可能直接参与全球气候系统的反馈，并且这些反馈在许多不同的时间尺度上表现出复杂的动态。假设的反馈机制将有以下组成部分：在世界海洋中的N2固定率可以对大气中的温室气体，二氧化碳（CO2）的浓度产生影响，在几十年的时间尺度上（表面地球化学的变化）到千年（从N2固定和反硝化平衡的总NO3 -股票的变化）。大气中的二氧化碳浓度影响气候。反过来，气候系统可以通过控制铁尘的供应和影响上层海洋的分层来影响海洋中N2固定的速率。人类也在这种反馈循环的当前表现形式中发挥着直接作用，他们对灰尘产生的影响，通过沙漠边缘的农业，以及我们自己向大气中排放二氧化碳。这些影响的循环性质可以导致反馈系统，特别是在更长的时间尺度上。这个由安东尼·迈克尔斯博士领导的跨学科合作研究小组，我们将研究这个系统的每个组成部分，然后模拟假设的反馈过程。由于这个系统的各个部分的相互作用，围绕着可以固定N2的原核微生物的独特行为和生物化学，这个反馈回路应该在各种时间尺度上表现出复杂的行为。在这项研究中，我们将进行一系列有针对性的实验和实地观察，以了解和参数化这一全球过程的每一部分，包括通过灰尘沉积直接控制海洋N2固定。这种理解将为建模过程提供支持，该过程将在几年到几千年的时间尺度上检查该系统的复杂动态。模拟过程将通过与海洋地球化学随时间变化的数据进行比较来评估