Roots, Weathering, and the Terrestrial Phosphorus Cycle of the Late Devonian

晚泥盆世的根源、风化和陆地磷循环

• 批准号: 1850878
• 负责人: Gabriel Filippelli
• 金额: $ 30.54万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-15 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1850878&HistoricalAwards=false
• 关键词: Roots; Weathering; Terrestrial; Phosphorus; Cycle

For the first 4 billion years of Earth history, the land surface was devoid of biological activity. There were no plants, no forests, no roots, and little to no soil. Then, in a geologic blink of an eye, a whole series of evolutionary advances began on land about 400 million years ago. Plants evolved to make harder, more rigid cell structures, allowing them to reach above their neighbors to catch sunlight and downward with roots to both capture more energy and to develop stabilizing structures. These early roots weathered the crust and formed the first soils on Earth; however, the areal distribution of plants was sparse and early soils were rarely retained. Eventually, in the late Devonian period (roughly 330 million years ago), a forest ecosystem of an ancient fern-like tree, known as Archaeopteris, emerged, and the Earth's surface never lost its forest cover or soils since that time. The development of soil fundamentally changed the way weathering and erosion occurs, as the newly evolved plant acids enhanced the chemical weathering of rock into sediment. The ramifications of this massive transformation of the earth surface have been explored from several fronts, including mass extinctions in the oceans by a weathering pulse and release of phosphorus from land inducing a fertilization effect, similar to the excessive algal growth from fertilizer runoff and the modern Gulf of Mexico Dead Zone. But the scenario of a phosphorus-driven mass extinction in the ocean has never been corroborated at the source?namely using land-based records to see if soil development really did result in a dramatic loss of phosphorus from the landscape, and if so, whether this amount of phosphorus was adequate to drive a global "Dead Zone" in the ocean. Investigators will explore this critical interval by examining nutrient geochemical records stored in ancient lake sediments nearer the weathering sources. This work will involve an international collaboration and will train graduate and undergraduate students in geochemistry, geobiology, and earth history. Additionally, researchers will develop learning exercises for elementary and junior high students to explore the modern environmental issues of the Gulf of Mexico Dead Zone by looking through the lens of past examples of eutrophication. Investigators will quantify what impacts the proliferation and declines of various root-based ecosystems had on soil weathering and terrestrial cycling of the key global nutrient phosphorus. They will additionally examine relationships between carbon/nitrogen/phosphorus, carbon and nitrogen isotopic compositional changes, and geochemical proxies of weathering intensity during these terrestrial evolutionary steps to explore how the emergence of the modern soil systems impacted total soil nutrient and carbon balances. They will constrain terrestrial phosphorus mass balances to provide quantitative estimates of phosphorus export to the oceans, key evidence by which to test extant models of mid-late Devonian episodic oceanic anoxia. Their results will be coupled with complementary work done on palynology and isotope geochemistry by colleagues at the University of Southampton. The overarching hypothesis is that a temporal record of soil phosphorus transformations can be resolved from the sedimentary record of lacustrine systems in the mid-late Devonian. The intellectual merits of this work are to: (1) constrain terrestrial nutrient evolution during the late Devonian in reference to the extant paleobotanical record in a stratigraphic manner (which paleosols, as time-integrated records, do not independently do), (2) explore the potential role of nutrient limitation in driving evolution and extinction during one of the most dynamic transitions in terrestrial weathering and erosion conditions in Earth history, and (3) develop critical input data to constrain ocean reconstructions. Broader impacts include: (1) a significantly greater understanding of terrestrial nutrient dynamics, thus informing the broader geobiological community, (2) advanced training for a PhD student in biogeochemistry and Earth history, (3) facilitating research collaborations between IUPUI and Southampton, and informing several educational endeavors, including targeted class content applications and a science outreach program for 3rd ? 9th grade students with inadequate access to STEM resources at their schools.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在地球历史的前40亿年中，土地表面没有生物学活性。没有植物，没有森林，没有根，也没有土壤。然后，大约在4亿年前，一系列的进化进化始于地质眨眼。植物演变成使较硬，更僵硬的细胞结构的发展，使其能够在邻居上方抓住阳光并以根部捕捉阳光，以捕获更多的能量并发展稳定的结构。这些早期的根源使外壳形成了地球上的第一批土壤。但是，植物的面积分布稀疏，早期土壤很少保留。最终，在泥盆纪晚期（大约3.3亿年前），这是一棵古老的树木的森林生态系统，被称为考古学，出现了，地球的表面自那时以来从未失去其森林覆盖或土壤。随着新进化的植物酸增强了岩石的化学风化，土壤的发展从根本上改变了风化和侵蚀的发生方式。已经从几个方面探索了这种地球表面的这种大规模转化的后果，包括风化脉冲和磷从诱导施肥效应的土地中释放的磷在海洋中的大规模灭绝，类似于从肥径流中过度的藻类生长和墨西哥死亡区的现代海湾。但是，在海洋中以磷驱动的质量灭绝的情况从未得到证实？即使用陆基记录来查看水种发育是否真的导致景观中磷的巨大损失，如果是这样的话，是否足以驱动海洋中的全球“死亡区”。调查人员将通过检查在风化源附近的古湖沉积物中存储的养分地球化学记录来探索这一关键间隔。这项工作将涉及国际合作，并将培训地球化学，地球生物学和地球历史的毕业生和本科生。此外，研究人员将通过浏览过去的富营养化例子的镜头来为小学和初中学生开发学习练习，以探索墨西哥湾死区的现代环境问题。研究人员将量化各种基于根的生态系统对土壤风化和陆地循环的影响和下降的影响。他们还将研究碳/氮/磷，碳和氮同位素组成变化与在这些陆地进化步骤期间风化强度的地球化学代理之间的关系，以探索现代土壤系统的出现如何影响总土壤养分和碳平衡。它们将限制陆生磷质量平衡，以提供向海洋出口的磷的定量估计，这是通过测试中期泥盆纪中期生物性海洋性缺氧模型的主要证据。他们的结果将与南安普敦大学同事在同事上进行的关于孢粉学和同位素地球化学的互补工作。总体假设是，可以从中期泥盆纪的湖泊系统的沉积记录中解决土壤磷转化的时间记录。这项工作的智力优点是：（1）限制泥盆纪晚期期间的陆地养分进化，指的是现存的古植物记录以地层的方式（作为时间综合的记录，不独立地进行），（2），（2）探索在驱动企业在驱动企业中的潜在作用，以探索企业在驱动企业的潜在作用，从而在驱动境内的狂热范围内驱动了一项动态范围，从而驱动了一种动态的进化，而在驱动企业的范围内，却是在驱动企业中的狂热范围。历史和（3）开发关键的输入数据以限制海洋重建。更广泛的影响包括：（1）对陆地养分动态的了解得多，从而为更广泛的地球生物学界提供了信息，（2）对生物地球化学和地球历史上博士生的高级培训，（3）促进IUPUI和SouthAmpton之间的研究合作，并在包括几项教育阶级的内容中，包括针对性的课程和一项Science（包括Science and Science）？ 9年级学生在其学校获得STEM资源不足。该奖项反映了NSF的法定任务，并且使用基金会的知识分子优点和更广泛的影响审查标准，被认为值得通过评估来获得支持。

项目成果

Enhanced terrestrial nutrient release during the Devonian emergence and expansion of forests: Evidence from lacustrine phosphorus and geochemical records

泥盆纪森林出现和扩张期间陆地养分释放增强：来自湖相磷和地球化学记录的证据

• DOI: 10.1130/b36384.1
• 发表时间: 2022
• 期刊: GSA Bulletin
• 作者: Smart, Matthew S.;Filippelli, Gabriel;Gilhooly III, William P.;Marshall, John E.A.;Whiteside, Jessica H.
• 通讯作者: Whiteside, Jessica H.