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RUI: SG: Field and Laboratory Tests of Pyrogenic Organic Compounds in Australian Stalagmites as a Novel, High-Resolution Paleofire Proxy

RUI：SG：澳大利亚石笋中热原有机化合物作为新型高分辨率古火代理的现场和实验室测试

基本信息

批准号：
2147186
负责人：
Rhawn Denniston
金额：
$ 19.98万
依托单位：
Cornell College
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2022
资助国家：
美国
起止时间：
2022-08-01 至 2025-07-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2147186&HistoricalAwards=false
关键词：
RUI SG Field Laboratory Tests

项目摘要

The massive fires that burned across many parts of Australia in 2019-2020 are part of a global trend. Rising temperatures, coupled in some cases with prolonged droughts and fire suppression efforts, have created conditions conducive to unusually intense and widespread fires, including across many parts of the western United States. While exceptional for the century, it is unclear how unusual this fire activity is over long-term Earth history. In order to better place modern fire activity into a longer-term context, it is necessary to develop reconstructions of burning that occurred prior to the satellite era (1979-present). Records of ancient fire have been developed from burn scars on tree rings, from charcoal in lake sediments, and from fire-derived compounds deposited on and stored in glacial ice. In tropical Northwest Australia, it is not possible to recover such data. The goal of this project is to develop methods to recover fire-derived compounds from stalagmites in caves in that region. Results are expected to provide a clearer understanding of the utility of stalagmites as a novel record of past burning, and allow its application to other fire-prone regions, including the western United States. The project will also provide opportunities for undergraduate student training.Fire plays a critical role in the ecology of the tropics, but fuel loads, sources of ignition, and background climate conditions are often markedly different now than they were a century or more ago. Addressing the extent to which fire regimes are changing is complicated by the sparsity of high-resolution, long-term records of fire frequency and intensity spanning far beyond the instrumental era. Understanding the frequency and intensity of fire activity prior to the arrival of European pastoralists and during intervals of climate distinct from the modern era (e.g, the Little Ice Age: CE 1450- 1850) is critically important for managing current fires, estimating cascading effects of fires on plant and animal diversity, and maintaining ecosystem resiliency. This study aims to refine a novel paleofire proxy capable of addressing these limitations: pyrogenic organic compounds (including polycyclic aromatic hydrocarbons, PAHs) in stalagmites. Previous research by the PI and collaborators has revealed that stalagmites from a tropical Australian cave preserve changes in the type and abundance of pyrogenic compounds over time, with these shifts consistent with recent fire activity proximal to the cave. Burning of biomass produces PAHs, which are then transported into the underlying cave by monsoon rains, and incorporated into stalagmites as they crystallize from dripwater. While these results are extremely promising, the biochemical and hydrological mechanics of the cave system need to be further scrutinized before this method can be applied more widely. Toward that end, the PI and collaborators will perform field and laboratory experiments: (i) measurements of organic compounds such as PAHs in soil and cave dripwater prior to, immediately following, and a year after a prescribed burn over the cave site, (ii) replication of pyrogenic organic compound distributions in a coeval stalagmite sample, and (iii) comparison of the paleofire signals in a 20th century stalagmite to remote sensing data and records of fire derived from historical documents. This work will also provide training to several undergraduates at Cornell College in field and laboratory methods, a critical step in advancing their careers as scientists.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.

2019 - 2020年澳大利亚许多地区发生的大火是全球趋势的一部分。气温上升，加上在某些情况下长期干旱和灭火工作，创造了有利于异常激烈和广泛火灾的条件，包括美国西部许多地区。虽然在世纪是例外，但目前还不清楚这种火灾活动在长期的地球历史中有多不寻常。为了更好地将现代火灾活动置于更长期的背景下，有必要对卫星时代（1979年至今）之前发生的燃烧进行重建。关于古代火灾的记录来自树木年轮上的烧伤痕迹、湖泊沉积物中的木炭以及沉积在冰川冰上并储存在冰川冰中的火衍生化合物。在热带澳大利亚西北部，不可能恢复这样的数据。该项目的目标是开发从该地区洞穴石笋中回收火衍生化合物的方法。结果预计将提供一个更清晰的了解石笋作为一种新的记录过去燃烧的效用，并允许其应用到其他火灾易发地区，包括美国西部。该项目还将为本科生提供培训机会。火在热带生态学中起着至关重要的作用，但燃料负荷，点火源和背景气候条件与世纪或更多年前相比往往有明显的不同。解决火灾制度的变化程度是复杂的稀疏的高分辨率，长期记录的火灾频率和强度跨越远远超过仪器时代。了解火灾活动的频率和强度之前，欧洲牧民的到来，并在间隔的气候不同于现代时代（例如，小冰河时代：CE 1450 - 1850）是至关重要的管理目前的火灾，估计级联效应的火灾对植物和动物的多样性，并保持生态系统的弹性。本研究的目的是完善一种新的古火代理能够解决这些限制：石笋中的热解有机化合物（包括多环芳烃，多环芳烃）。PI和合作者先前的研究表明，来自澳大利亚热带洞穴的石笋随着时间的推移保留了热原化合物的类型和丰度的变化，这些变化与洞穴附近最近的火灾活动一致。生物质燃烧产生多环芳烃，这些多环芳烃随后被季风雨带入地下洞穴，并在石笋从滴水中结晶时被纳入石笋。虽然这些结果是非常有前途的，洞穴系统的生物化学和水文力学需要进一步审查之前，这种方法可以更广泛地应用。为此，PI和合作者将进行现场和实验室实验：（i）在洞穴遗址上进行规定的燃烧之前、之后和之后一年，测量土壤和洞穴滴水中的有机化合物，如多环芳烃，（ii）复制同时代石笋样品中的热解有机化合物分布，（iii）将20世纪世纪石笋中的古火信号与遥感数据和历史文献中的火灾记录进行比较。这项工作还将为康奈尔大学的几名本科生提供实地和实验室方法的培训，这是推进他们作为科学家的职业生涯的关键一步。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。