CAREER: Understanding biosphere-geosphere coevolution through carbonate-associated phosphate, community archives, and open-access education in rural schools

磷是生命所必需的营养物质。今天，磷在海洋中以极低的丰度存在，限制了生物圈的生产力。大部分磷来自大陆磷酸盐矿物的风化作用。然而，在地球历史的最初10到20亿年里，没有适合气候变化的大陆。在第一个大陆出现在海平面(约32亿至26亿年前)后不久，微生物进化出了进行氧合光合作用的能力，这导致了富氧的大气和初级生产力的大幅提高。海洋和大气的氧合作用与地球第一批大陆的风化有直接关系吗？这项研究将记录古代海洋中磷的浓度~2到0.5Ga，以检验海洋微生物的进化是否与地球被冰覆盖时早期大陆的风化有关。最终，磷的丰富可能促成了好氧生物和多细胞生物的进化。这项研究将被整合到与当地高中教师共同为邻近农村地区开发的新地球科学课程中。该项目将开发开放访问的课堂和基于现场的学习模块和虚拟实地旅行，将学生与宾夕法尼亚州寒武纪大爆发-宏观动物的进化-联系起来。新课程的效果将通过在接触之前和之后进行的一系列知识评估以及随后几年的“知识提升”来评估。大西洋中部的高中教师将在课堂上接受各种资源的培训。自从生命诞生以来，微生物一直与碳酸盐矿物和地球表面的化学进化密切相关。20亿年前光合作用的代谢创新促进了氧气的上升，提高了全球初级生产力，并永久性地改变了生物地球化学循环。然而，关于微生物为什么在生命历史上相对较晚地进化出光合作用的能力，以及是什么控制了随后微生物进化的速度，人们知之甚少。这一职业奖项的主要目标是评估磷酸盐的可用性--磷酸盐是所有生命的基本营养素--在拥有原始微生物和新陈代谢的质地和地球化学证据的环境中。中元古代生产力的降低是否是磷酸盐储集层被含氧光养生物耗尽的症状？冠群真核生物和后生动物的演化是否受新元古代全球冰川和超大陆解体的风化磷酸盐的影响？该项目通过在元古界全球冰川、构造以及现有的时间和成岩框架内，通过碳酸盐伴生磷酸盐(CAP)在现有前寒武纪样本集上重建海水[P]，检验了增强磷酸盐有效性对真核生物和后生动物进化至关重要的假设。这项研究将通过以下方式提高我们对CAP及其在地球和天体生物学中的效用的理解：(1)分析具有丰富现有成岩和地球化学数据的相同前寒武纪样本中的CAP，以及(2)进行生长实验以开发矿物特定的CAP-[P]海水定标。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Phosphorus is an essential nutrient for life. Today, phosphorus exists in extremely low abundance in the oceans limiting the productivity of the biosphere. The majority of phosphorus is derived from weathering of phosphate minerals from continents. However, for the first one to two billion years of Earth history, there were no continents to weather. Shortly after the first continents emerged above sea level (~3.2 to 2.6 billion years ago, Ga), microbes evolved the ability to perform oxygenic photosynthesis, which led to an oxygen-rich atmosphere and massive increase in primary productivity. Was the oxygenation of the oceans and atmosphere directly related to weathering of Earth’s first continents? This study will develop a record of the concentration of phosphorus in ancient oceans ~2 to 0.5 Ga to examine if the evolution of marine microorganisms was linked to weathering of early continents when the Earth was covered in ice. Ultimately, phosphorus abundance may have enabled the evolution of aerobic and multicellular organisms. The research will be integrated into new Earth sciences curricula developed with local high school teachers for neighboring rural districts. The project will develop open-access classroom and field-based learning modules and virtual field trips that connect students to the Cambrian explosion—the evolution of macroscopic animals—in the Pennsylvania landscape. The efficacy of the new curricula will be assessed through serial knowledge assessments implemented before and after exposure and “knowledge boosts” in subsequent years. Mid-Atlantic high school teachers will be trained in various resources to be implemented in their classrooms.Microbes have been intimately linked to carbonate minerals and the chemical evolution of Earth’s surface since life began. The metabolic innovation of oxygenic phototrophy 2 billion years ago contributed to the rise of oxygen, increased global primary productivity, and permanently changed biogeochemical cycles. However, little is known about why microbes evolved the ability to photosynthesize relatively late in the history of life, and what controlled the pace of subsequent microbial evolution. The primary goal of this CAREER award is an assessment of phosphate availability—an essential nutrient for all life—in the environments that host textural and geochemical evidence for primitive microbes and emergent metabolisms. Was the reduced productivity of the Mesoproterozoic a symptom of a phosphate reservoir depleted by oxygenic phototrophs? Was the evolution of crown group eukaryotes and metazoans fertilized by weathering-derived phosphate from Neoproterozoic global glaciations and the breakup of supercontinents? This project tests the hypothesis that enhanced phosphate availability was essential to the evolution of eukaryotes and metazoans by reconstructing seawater [P] via carbonate-associated phosphate (CAP) on existing Precambrian sample sets within the context of Proterozoic global glaciations, tectonics, and existing temporal and diagenetic frameworks. The research will improve our understanding of CAP and its utility for geo- and astrobiology by (1) analyzing CAP in the same Precambrian samples that have a wealth of existing diagenetic and geochemical data, and (2) performing growth experiments to develop mineral-specific CAP-[P]seawater calibrations.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.