Collaborative Research: Biological and geochemical controls on phosphorus bioavailability in arctic tundra

合作研究：北极苔原磷生物利用度的生物和地球化学控制

• 批准号: 1914552
• 负责人: Elizabeth Herndon
• 金额: $ 90.75万
• 依托单位: Kent State 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: 2019-11-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1914552&HistoricalAwards=false
• 关键词: Collaborative; Research; Biological; geochemical; controls

Phosphorus is an essential nutrient for life, but in some environments it is in short supply, putting limits on plant growth and decomposition. Plants and microorganisms take up phosphorus from the water in soil in the form of dissolved phosphate, which can also be removed from solution by binding to soil minerals. In particular, iron oxide minerals strongly bind phosphate and may regulate its availability to plants and microorganisms. This project will investigate how geochemical and biological systems compete for phosphate in arctic tundra soils near Toolik Field Station, Alaska, where soil warming and permafrost thaw are altering carbon and water budgets, which in turn affect soil moisture and nutrient availability. This research will determine how soil properties can affect this competition for phosphate, with broad consequences for plant growth and carbon dynamics in Arctic terrestrial ecosystems. This project also supports two early career scientists, a postdoctoral scholar, and multiple graduate and undergraduate students. Furthermore, all participants will design data-driven educational activities (DataNuggets), which will be used to communicate scientific results across multiple platforms.The ability of terrestrial ecosystems to store carbon depends largely on nutrient availability, which affects both plant growth and decomposition rates. Phosphorus (P) is often a limiting nutrient, and P cycling in tundra ecosystems is widely assumed to occur primarily through biological pathways, in which biological P demand is met by enzymatic release of phosphate from organic molecules. However, this conceptual model does not account for iron (Fe) oxides, which may serve as nutrient traps that regulate phosphate solubility and serve as P sources or sinks under different redox conditions, even in organic soils. The processes controlling the quantity and bioavailability of oxide-bound P under different environmental conditions remain unclear, limiting our ability to predict how P availability might change with expected hydrological changes. Fluctuating redox conditions drive microbial transformation of Fe oxides and may also regulate P bioavailability. Thus, biological and geochemical controls over P dynamics may vary as a function of hydrology and redox regime across arctic landscapes. This project will use a sensor network to characterize redox and pH patterns in environments typical of low-arctic tundra and investigate biological and geochemical P competition across these gradients. The investigators will quantify competitive partitioning of P between abiotic (Fe oxides and other minerals) and biotic (microbial and plant) sinks. They will test the hypothesis that geochemical sorption and co-precipitation processes effectively compete with plant roots and microorganisms for phosphate in tundra soils. The study will provide the first assessment of the importance of geochemical versus biological controls on P bioavailability and how they might be altered by hydrological changes in these sensitive ecosystems.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.

磷是生命所必需的营养素，但在某些环境中，磷供应不足，限制了植物的生长和分解。植物和微生物以溶解的磷酸盐的形式从土壤中的水中吸收磷，磷酸盐也可以通过与土壤矿物质结合而从溶液中去除。特别是，氧化铁矿物质强烈结合磷酸盐，并可调节其对植物和微生物的可用性。该项目将研究地球化学和生物系统如何在阿拉斯加图里克野外站附近的北极苔原土壤中竞争磷酸盐，土壤变暖和永久冻土融化正在改变碳和水的收支，这反过来又影响土壤水分和养分的可用性。这项研究将确定土壤特性如何影响这种对磷酸盐的竞争，并对北极陆地生态系统的植物生长和碳动态产生广泛影响。该项目还支持两名早期职业科学家、一名博士后学者以及多名研究生和本科生。此外，所有参与者将设计数据驱动的教育活动（DataNuggets），用于在多个平台上交流科学成果。陆地生态系统储存碳的能力在很大程度上取决于养分的可用性，这会影响植物的生长和分解速率。磷（P）通常是限制性营养素，并且冻原生态系统中的P循环被广泛认为主要通过生物途径发生，其中生物P需求通过从有机分子中酶促释放磷酸盐来满足。然而，这个概念模型不考虑铁（Fe）的氧化物，这可能是作为营养陷阱，调节磷酸盐的溶解度，并作为磷源或汇在不同的氧化还原条件下，即使在有机土壤。在不同的环境条件下，氧化物结合磷的数量和生物利用度的控制过程仍然不清楚，限制了我们的能力，以预测如何P的可用性可能会随着预期的水文变化而变化。波动的氧化还原条件驱动铁氧化物的微生物转化，也可能调节磷的生物利用度。因此，生物和地球化学控制P动力学可能会有所不同，水文和氧化还原制度在整个北极景观的功能。该项目将使用传感器网络来表征低北极苔原典型环境中的氧化还原和pH模式，并调查这些梯度中的生物和地球化学磷竞争。研究人员将量化非生物（铁氧化物和其他矿物质）和生物（微生物和植物）汇之间的P竞争分配。他们将测试地球化学吸附和共沉淀过程有效地与植物根系和微生物竞争冻原土壤中磷酸盐的假设。这项研究将提供第一次评估的重要性，地球化学与生物控制对磷的生物利用度，以及它们如何可能被改变水文变化在这些敏感的ecosystems.This奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。