ETBC Collaborative Research: Weathering Under Cover: Role of biofilms in mineral weathering and nutrient uptake in the mycorrhizosphere

智力优点：最近几个领域的进展为基于过程的研究维管植物的地球化学机构奠定了基础-特别是，它们的生理学如何驱动地球？是什么？耐候引擎？从风化层中提取矿物质来建造土壤，化学侵蚀大陆，并将海洋/大气的化学物质设定在地质时间尺度上。这样的研究是及时的，需要解释全球变化的土壤地质记录，并预测陆地固碳对全球二氧化碳循环和土壤可持续性的影响，在人类改变的世界。PI的总体概念是，植物驱动的风化速率和机制各不相同，取决于地质环境和生态系统阶段。他们把重点放在初级演替环境中，植物必须通过化学风化从土壤中提取养分。的前提是，许多植物对这些条件的一个关键的适应是mycorrogenosphere生物膜的发展，附着在矿物表面的根系和微本地化的生物学，化学和水文风化和养分吸收在根系矿物界面。在这个微米尺度上，溶解和生物质量转移发生在非常小的距离内，并且与大量土壤水相对隔离，从而增加宏观养分获取效率并减少排水中的养分损失。中心假设是不同程度的营养限制（即，需要从矿物源中提取碱阳离子）影响生物膜的形成和风化/吸收功能。为了解决这一假设，PI建议使用复制外生菌根幼苗系统在生长实验中，并通过操纵灌溉溶液和初始矿物组成来改变大量土壤水和主要矿物中Ca和K的可用性。这项研究将深入了解矿物风化的微米尺度过程与生态系统尺度的养分获取过程以及最终全球尺度的大陆剥蚀过程之间的联系机制。更广泛的影响：八名本科生将参与该项目。由于研究人员的独特组合，学生将从一所社区学院，一所四年制本科学院和两所研究型大学。拟议的研究将促进包括太平洋西北国家实验室，美国林务局，农业研究服务和学术机构在内的科学家合作网络。研究结果将传播到科学网络，包括临界区探索网络和哈伯德布鲁克生态系统研究，并通过为初中和高中课堂设计的教学模块向公众介绍。最终，这项工作将成为改善植物营养和土壤可持续性以及更好地了解陆地和水圈碳固存的基础。

Intellectual merit: Recent advances across several fields set the stage for process-based research into the biogeochemical agency of vascular plants -- in particular, how their physiologies drive Earth?s ?weathering engine? to extract mineral matter from regolith to build soils, chemically denude the continents, and set the chemistry of the ocean / atmosphere on geologic timescales. Such research is timely andneeded to interpret pedo-geologic records of global change, and to forecast the effects of terrestrial C sequestration on the global CO2 cycle and soil sustainability in a human-altered world. The PIs overarching concept is that plant-driven weathering rates and mechanisms vary, depending on geologic setting and ecosystem phase. They focused on primary-successional settings, where plants must extract nutrients from soils by chemical weathering. The premise is that a key adaptation of many plants to these conditions is development of mycorrhizospheric biofilms, which attach the root system to mineral surfaces and micro-localize the biology, chemistry, and hydrology of weathering and nutrient uptake at the root system-mineral interface. At this micron scale, dissolution and biological mass transfers occur over very small distances and in relative isolation from bulk soil water, thereby increasing macroscopic nutrient acquisition efficiency and decreasing nutrient loss in drainage. The central hypothesis is that varying degreesof nutrient limitation (i.e., the need to extract base cations from mineral sources) influence biofilm development and weathering/uptake function. To address this hypothesis, the PIs propose to use replicated ectomycorrhizal seedling systems in a growth experiment, and vary the availability of Ca and K in bulk soil water and primary minerals by manipulating irrigation solutions and initial mineral composition. This research will provide insights into the mechanisms that link micron-scale processes of mineral weathering to ecosystem-scale processes of nutrient acquisition and ultimately global-scale processes of continental denudation.Broader Impact: Eight undergraduate students will work on this project. Because of the unique combination of researchers, students will be drawn from a community college, a four-year undergraduate college, and two research universities. The proposed research will foster a collaborative network of scientists that includes Pacific Northwest National Laboratory, the US Forest Service, the Agricultural Research Service, and academic institutions. The results will be disseminated to science networks including the Critical Zone Exploration Network and the Hubbard Brook Ecosystem Study, and introduced to the general public through teaching and learning modules designed for middle and high school classrooms. Ultimately, this work will serve as a foundation for improving plant nutrition and soil sustainability, and better understanding terrestrial and hydrospheric carbon sequestration.