RAPID: Collaborative Research: Hydrologically driven export of pyrogenic carbon and nutrients in fire-impacted watersheds

美国西部野火的规模和频率正在增加。这些野火通过燃烧植被和表层土壤以及破坏山坡稳定，使其更容易受到侵蚀，从而极大地改变了地球表面。这些变化共同影响了降水和其他物质如何被输送到河流。河流是将水和物质从源头向下游输送并最终输送到海洋的主要管道。然而，由于捕捉不可预测的野火事件的挑战，有一个缺乏了解的组成，浓度和时间的材料出口出流域火灾后立即。被运输的物质包括烟灰和木炭（称为热解碳）和必需的营养素，如氮。这些物质对当地生态系统功能、全球生物地球化学循环和下游饮用水资源的水质都很重要。这项研究将收集和分析水和土壤样本燃烧流域后，圣克拉拉单位闪电复杂的火灾。在火灾发生之前，对流域进行了仪器化，并提供了一个分析火灾发生前后水文和生物化学数据的机会。这项研究将产生的数据，将有助于了解野火对用于饮用水的水资源的影响，并为减轻这些影响提供有价值的信息。这项研究的目标是揭示改变山坡水文和径流在新烧毁的景观将如何影响河流储存和出口的生态和地球化学关键材料，特别关注氮和热解碳。这项研究将在中部沿海加州的一个源头流域进行，由于地中海气候，该流域经历了非常年径流。研究人员将在五个嵌套流域的出口处测量营养物和热解碳浓度，以评估先前确定的主要径流生成过程的差异如何影响观察到的物质运输。通过部署自动采样器和分光光度计，这项工作将开发一个丰富的数据集，从第一次火灾后降水事件到夏季干燥的流中热解碳和营养物质浓度。这对于构建受火灾影响的流域水文和地球化学过程的综合视图至关重要。该项目将为本科生和研究生提供培训，并生成数据，为圣克拉拉谷水区提供有关将燃烧过的流域中的材料出口到饮用水源的信息。该项目由地球科学部的水文科学、地球生物学和低温地球化学项目以及环境生物学部的生态系统科学集群项目共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Wildfire magnitude and frequency are increasing across the western US. These wildfires are drastically altering Earth’s surface by burning vegetation and surface soils and destabilizing hillslopes, making them more prone to erosion. Together, these alterations impact how precipitation and other material is transported to rivers. Rivers are the main conduit for transferring water and materials from headwaters further downstream and ultimately to oceans. However, given the challenges of capturing unpredictable wildfire events, there is a lack of understanding of the composition, concentration, and timing of material export out of watersheds immediately following fires. Included in the material being transported is soot and charcoal (called pyrogenic carbon) and essential nutrients, such as nitrogen. These materials are important for local ecosystem function, global biogeochemical cycles, and for the water quality of downstream drinking water resources. This study will collect and analyze water and soil samples from burned watersheds following the fires of the Santa Clara Unit Lightning Complex. The watersheds were instrumented prior to the fires and provide an opportunity to analyze hydrologic and biochemical data previous to and after the fire. This study will generate data that will help to understand the impacts of wildfires on water resources used for drinking water purposes and provide valuable information for mitigation of these impacts.The goal of this research is to reveal how altered hillslope hydrology and streamflow in newly burned landscapes will impact the in-stream storage and export of ecologically and biogeochemically critical material, with specific focus on nitrogen and pyrogenic carbon. This research will be conducted in a headwater catchment in central coastal California, which experiences non-perennial streamflow due to its Mediterranean climate. Researchers will couple measurements of nutrient and pyrogenic carbon concentrations at the outlets of five nested watersheds to assess how previously identified differences in dominant streamflow generation processes influence observed material transport. Through deployment of automated samplers and a spectrophotometer, this work will develop a rich dataset of in-stream pyrogenic carbon and nutrient concentrations from the very first post-fire precipitation event to the summer dry down. This is critical for constructing an integrative view of hydrologic and biogeochemical processes in fire- impacted watersheds. The project will provide train undergraduate and graduate students and generate data that will inform the Santa Clara Valley Water District on the export of materials from burned watershed into drinking water sources. This project is jointly funded by the Hydrologic Sciences and Geobiology and Low-Temperature Geochemistry programs in the Division of Earth Sciences and the Ecosystem Science Cluster program in the Division of Environmental Biology.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.