Collaborative Research: Tapping an unused biomarker for insights of past evaporation

合作研究：利用未使用的生物标记来了解过去的蒸发

• 批准号: 2039795
• 负责人: Aaron Diefendorf
• 金额: $ 36.73万
• 依托单位: University of Cincinnati Main Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2039795&HistoricalAwards=false
• 关键词: Collaborative; Research; Tapping; unused; biomarker

Changes to the hydrological cycle, including precipitation and evaporation, have impacts on society and ecosystems at local to global scales. Therefore, it is critical to understand how the hydrological cycle responds to changes in climate as warming forces documented and projected changes in precipitation and extreme events. However, the effects of warming on evaporation are more challenging to anticipate, and without the evaporation term, the complete water budget cannot be constrained. By utilizing various existing proxies preserved in lake sediments, it is possible to track past precipitation and temperature, however there are few proxies that record evaporation. This project will help fill in this gap by developing the use of a group of biologically produced organic compounds called highly branched isoprenoids (HBIs). These HBIs are produced by diatoms and should contain a chemical signal of the lake water the diatoms live in. This project will focus on this connection between the HBIs and the signal of evaporation through a series of field-based modern calibrations and apply these calibrations to recent lake sediment archives to test their ability to reproduce evaporation. The goal of this work is to advance evaporation reconstruction both temporally and spatially, ultimately improving paleohydrologic reconstructions and future predictions of hydrologic change. The national health, prosperity and welfare can be safeguarded with a more complete understating of the evolution of the hydrological cycle. This collaborative project with The College of Wooster will provide research opportunities to undergraduate students while developing mentoring skills and experience for the UC graduate students. The Browns Lake field site in Ohio will be used in to help students gain field and lab experiences during summer programs at Wooster designed to recruit STEM students into the geosciences from underrepresented groups. This project will provide training in project design, data synthesis, interpretation and dissemination for graduate students. This research will also increase broader public knowledge and awareness of climate change by creating hands-on activities at the Northside Farmer’s Market in Cincinnati. This project will advance the use of hydrogen isotopes to reconstruct lake evaporation and hence contribute to the understanding of past hydrologic balance. Specifically, this work will consider diatom-derived highly branched isoprenoids (HBIs) as a paleohydrology proxy. If the hydrogen isotopes of HBIs record lake water hydrogen isotopes, then, when combined with other proxies, past records of lake water evaporation can be generated to constrain the complete hydrologic cycle. To accomplish this, this project will first investigate how diatom growth habitat, water chemistry, and timing of HBI synthesis influences the hydrogen isotopic composition of HBIs. Diatom HBIs will be collected from pelagic and benthic habitats across a suite of lakes that vary in water chemistry (i.e., pH, salinity), as this influences diatom species composition. The timing of seasonality of HBI production will be determined by collection of bimonthly sediment trap samples from Brown’s Lake in northeastern Ohio over two years. Once these controls on HBI hydrogen isotopes are addressed, this project will then determine the sensitivity of HBI hydrogen isotopes in sediment archives to known changes in local hydroclimate. This will be completed by examining HBIs in lake sediments where established records of evaporation and precipitation already exist. The development of HBIs proposed here will provide site selection criteria and necessary calibration information to use hydrogen isotopes of HBIs as a proxy for lake water evaporation, ultimately improving paleohydrological reconstructions from lake sediments. The project broader impacts will benefit society by 1) establishing a partnership with the College of Wooster, a primarily undergraduate institution, by creating research experiences for undergraduate students that will further the research proposed here; 2) creating a unique opportunity for undergraduate students to gain advanced and critical research skills, beyond the classroom, and preparing them for careers in the geosciences or STEM fields; 3) providing training in project design, data synthesis, interpretation and dissemination for graduate and undergraduate students in addition to mentoring students to enhance educational and career development; 4) encouraging the inclusion of and increasing the number of women in STEM by providing support for, and the training of the Ph.D. student, along with support for the training of undergraduate students; and 5) public outreach in the form of geoscience hands-on activities at the Northside Farmer’s Market in Cincinnati, a unique venue to help increase broader public knowledge and awareness of climate change.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.

水文循环的变化，包括降水和蒸发，对地方和全球范围内的社会和生态系统产生影响。因此，随着变暖力量记录和预测降水和极端事件的变化，了解水文循环如何响应气候变化至关重要。然而，变暖对蒸发的影响更难以预测，并且如果没有蒸发项，就无法限制完整的水预算。通过利用湖泊沉积物中保存的各种现有代理，可以跟踪过去的降水量和温度，但记录蒸发量的代理很少。该项目将通过开发一组称为高度支化类异戊二烯 (HBI) 的生物产生的有机化合物的使用来帮助填补这一空白。这些 HBI 由硅藻产生，应包含硅藻所生活的湖水的化学信号。该项目将通过一系列基于现场的现代校准来重点研究 HBI 与蒸发信号之间的联系，并将这些校准应用于最近的湖泊沉积物档案，以测试其再现蒸发的能力。这项工作的目标是在时间和空间上推进蒸发重建，最终改善古水文重建和未来水文变化的预测。通过更全面地了解水文循环的演变，可以保障国民健康、繁荣和福利。这个与伍斯特学院的合作项目将为本科生提供研究机会，同时为加州大学研究生培养指导技能和经验。俄亥俄州的布朗斯湖现场将用于帮助学生在伍斯特暑期项目中获得现场和实验室经验，该项目旨在从代表性不足的群体中招收 STEM 学生进入地球科学领域。该项目将为研究生提供项目设计、数据合成、解释和传播方面的培训。这项研究还将通过在辛辛那提北区农贸市场开展实践活动，增加公众对气候变化的更广泛的了解和认识。该项目将推进氢同位素的使用来重建湖泊蒸发，从而有助于了解过去的水文平衡。具体来说，这项工作将考虑硅藻衍生的高度支化的类异戊二烯（HBI）作为古水文学代理。如果HBI的氢同位素记录了湖水氢同位素，那么当与其他代理结合时，可以生成过去的湖水蒸发记录以约束完整的水文循环。为了实现这一目标，该项目将首先研究硅藻生长栖息地、水化学和 HBI 合成时间如何影响 HBI 的氢同位素组成。硅藻 HBI 将从一系列湖泊的中上层和底栖栖息地收集，这些湖泊的水化学成分（即 pH 值、盐度）各不相同，因为这会影响硅藻物种的组成。 HBI 生产的季节性时间将通过两年内从俄亥俄州东北部布朗湖每两个月采集一次沉积物捕集器样本来确定。一旦解决了对 HBI 氢同位素的控制问题，该项目将确定沉积物档案中的 HBI 氢同位素对当地水文气候已知变化的敏感性。这将通过检查湖泊沉积物中的 HBI 来完成，其中已经存在蒸发和降水的既定记录。这里提出的 HBI 的开发将提供选址标准和必要的校准信息，以使用 HBI 的氢同位素作为湖水蒸发的代理，最终改善湖泊沉积物的古水文重建。该项目更广泛的影响将通过以下方式造福社会：1）与伍斯特学院（主要是本科院校）建立合作伙伴关系，为本科生创造研究经验，从而进一步推进此处提出的研究； 2) 为本科生创造独特的机会，让他们在课堂之外获得先进和关键的研究技能，并为他们在地球科学或 STEM 领域的职业生涯做好准备； 3) 为研究生和本科生提供项目设计、数据综合、解释和传播方面的培训，并指导学生加强教育和职业发展； 4) 通过为博士生提供支持和培训，鼓励女性参与 STEM 并增加女性人数。学生，以及对本科生培训的支持； 5) 在辛辛那提北区农贸市场以地球科学实践活动的形式进行公众宣传，这是一个独特的场所，有助于提高公众对气候变化的更广泛的知识和认识。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。

项目成果

Hydrogen and carbon isotope fractionation in modern plant wax n-alkanes from the Falkland Islands

福克兰群岛现代植物蜡正烷烃中的氢和碳同位素分馏

• DOI: 10.1016/j.orggeochem.2022.104404
• 发表时间: 2022
• 期刊: Organic Geochemistry
• 影响因子: 3
• 作者: Corcoran, Megan C.;Diefendorf, Aaron F.;Lowell, Thomas V.;Hall, Brenda L.;Spoth, Meghan M.;Schartman, Anna;Brickle, Paul
• 通讯作者: Brickle, Paul