RAPID: Impacts of high magnitude wildfire on volcanic (lava tube) cave water chemistry, nutrient transport, activity and diversity of cave microbiome

众所周知，高强度的野火会破坏地表植被，使土壤消毒，并改变土壤的化学和水力性质；而它们对地下环境的影响相对较少。最近加州北部考德威尔和羚羊的野火烧毁了数百英亩的土地，其中包括保护火山(熔岩)洞穴的熔岩床国家纪念碑(熔岩床)97%的面积。火山洞穴为细菌和古菌提供了独特的栖息地，在有水的情况下，次生矿物特征(洞穴)在形态上也是多样化的。这项研究通过对洞穴水和微生物席进行采样，并对它们进行详细的无机化学和有机化学、微生物多样性和活性分析，研究了强烈的野火对火山洞穴生态系统的影响。这些来自受火灾影响的洞穴的数据将与早期研究的火灾前数据进行比较，并将来自未被烧毁地区的对照洞穴的数据进行比较，以量化由于野火而在洞穴内发生的变化。这个快速项目支持德克萨斯大学圣安东尼奥分校的一名少数族裔研究生、一家领先的拉美裔服务机构(HSI)和几名本科生(西班牙裔、少数族裔、女性和第一代)。与国家公园管理局合作，这项研究的结果将有助于为保护熔岩床国家纪念碑的敏感自然遗产提供信息，并将向公园的游客提供重要的科学发现。高强度野火对地表环境的影响是有据可查的，例如植被完全被摧毁，土壤消毒，土壤物理、化学和水力特性改变。然而，它们对包气带、浅含水层和洞穴等地下环境的影响研究相对较少。2020年的考德威尔大火和2021年加州北部的羚羊大火已经影响了美国加州熔岩床国家纪念碑97%的景观，那里有许多火山(熔岩)洞穴。火山(熔岩)洞穴是营养贫乏的无菌环境，但它们拥有丰富多样的细菌和古生菌，它们往往利用宿主岩石和洞穴内矿藏中可用的还原能源(例如，还原的铁、硫、锰或氮化合物)。洞穴中养分的可获得性在很大程度上取决于围岩(玄武岩)和大气水之间的相互作用，大气水通过表层土壤渗入洞穴，通过破裂的洞壁进入洞穴。这项快速研究将在火灾后水文响应时间内从受野火影响和未受影响地区的火山洞穴中获取水和微生物样本，并将其与样本中的化学和分子特征相关联。火灾后洞穴水化学的变化将通过测量阳离子、阴离子、微量金属和溶解有机物的浓度，并与火灾前早期研究和对照洞穴的数据进行比较来量化。16S rRNA基因测序分析和ATP将用于跟踪火灾后洞穴内微生物多样性和活动的变化。德克萨斯大学圣安东尼奥分校和新墨西哥大学的一名研究生和几名本科生将进行样本采集和随后的实验室分析。这些结果将提供有关地表野火对地下生态系统影响的关键信息。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。

Wildfires of high magnitude are known to cause destruction of surface vegetation, soil sterilization, and alteration of soil chemical and hydraulic properties; whereas their effects on subsurface environments are relatively unknown. Recent Caldwell and Antelope wildfires in northern California burnt over hundreds of acres of landscape which included 97% of the area in Lava Beds National Monument (Lava Beds) that protects volcanic (lava) caves. The volcanic caves provide a unique habitat for bacteria and archaea, and morphologically diverse secondary mineral features (speleothems) in the presence of water. This study investigates the impacts of intense wildfires on volcanic cave ecosystems by sampling cave water and microbial mats, and analyzing them for detailed inorganic and organic chemistry, microbial diversity and activity. This data from fire-affected caves will be compared with pre-fire data from earlier studies, and the control caves from the unburnt areas, to quantify the changes occurred within the caves due to wildfires. This RAPID project supports one minority graduate student at the University of Texas at San Antonio, a leading Hispanic Serving Institution (HSI) and several undergraduate students (Hispanic, minorities, women and first generation). In collaboration with the National Park Service, the findings of this study will help inform protection of the sensitive natural heritage at Lava Beds National Monument, and important scientific findings will be made available to the visitors of the park. Impacts of high magnitude wildfires on surface environments are well documented such as complete destruction of vegetation, soil sterilization, and alteration of physical, chemical and hydraulic soil properties. However, their effects on subsurface environments like vadose zones, shallow aquifers, and caves are relatively understudied. The Caldwell Fire in 2020 and Antelope Fire in 2021 in northern California have affected 97% of Lava Beds National Monument (California, USA) landscape that hosts numerous volcanic (lava) caves. Volcanic (lava) caves are nutrient-poor, aphotic environments, and yet they host a rich diversity of bacteria and archaea which often utilize reduced energy sources (e.g., reduced iron, sulfur, manganese, or nitrogen compounds) available within the host rock and mineral deposits within the caves. Availability of nutrients in caves greatly depends upon the interactions between host rock (basalt) and meteoric water that infiltrates through surface soils into caves through fractured cave walls. This RAPID study will obtain water and microbial samples from volcanic caves in wildfire affected and unaffected areas at Lava Beds, during a post-fire hydrologic response time, and correlate it with chemical and molecular signatures in the samples. Post-fire changes in cave water chemistry will be quantified by measuring concentrations of cations, anions, trace metals, and dissolved organic matter, and comparing with pre-fire data from earlier studies, and from control caves. Analysis of 16S rRNA gene sequencing and ATP will be used to track changes in microbial diversity and activity within the caves during the post-fire period. One graduate student and several undergraduate students from the University of Texas at San Antonio and University of New Mexico will perform samples collection and subsequent laboratory analyses. These results will provide a key information regarding impacts of surface wildfires on subsurface 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.