Collaborative Research: Identifying basin-specific controls on isotopic and chronological offsets of lake sediment leaf wax hydrogen isotope records

合作研究：确定对湖泊沉积物叶蜡氢同位素记录的同位素和年代偏移的流域特定控制

• 批准号: 1636740
• 负责人: Aaron Diefendorf
• 金额: $ 22.26万
• 依托单位: University of Cincinnati Main Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1636740&HistoricalAwards=false
• 关键词: Collaborative; Research; Identifying; basin; specific

To determine how future precipitation might change, it is important to have a baseline of how precipitation changed in the past. However, determining past precipitation, prior to the generation of instrumental records, has remained challenging and necessitates the use of precipitation proxies that are preserved in the geologic record. Biological proxies, such as leaf waxes, hold promise in this regard as the hydrogen isotopic composition of leaf wax primarily reflects that of precipitation. Therefore, leaf waxes preserved in lake sediments are a potential source of high resolution information about how precipitation and the water cycle have changed over geologic time. However, the transfer of modern leaf waxes to lake sediments appears to introduce offsets in hydrogen isotope values. This project will help define these offsets and identify the factors that control them, thus allowing for improved reconstructions of past hydrological conditions. Until these offsets are evaluated, and their influence measured, the quantitative link between sedimentary leaf wax and precipitation will remain limited. Identification of these factors will allow selection of lakes where the effects of these offsets are minimal. This is critical for constraining past changes in hydrology prior to the instrumental record and will help anticipate future hydrologic change. This project will benefit society by creating educational and research experiences for undergraduates through interdisciplinary collaborations with St. Lawrence University, a primarily undergraduate institution. This will improve STEM field retention by providing research and training experiences for undergraduate students to develop advanced research skill sets, expand scientific understanding, and strengthen preparation for graduate studies or a career in the geosciences. Finally, this research will promote a broader public understanding of the geosciences and appreciation of scientific research by expanding on museum exhibits in collaboration with the Cincinnati Museum Center, a large urban cultural institution.Past precipitation remains a challenge to quantify. Biological proxies, such as leaf waxes, hold promise in this regard as the hydrogen isotopic composition of leaf wax primarily reflects plant source water (i.e., precipitation). However, quantitative paleohydrology, as inferred from precipitation hydrogen isotopic composition, is limited by a poor understanding of the taphonomic processes governing the source, integration, and transport of leaf waxes from plants to sediments. This project will address two significant gaps in our understanding of lake sediment leaf waxes. First, the investigators will determine how vegetation proximity influences leaf wax hydrogen isotope signals in lake sediments. Second, they will determine how important reworking of older leaf waxes via fluvial erosion impacts the apparent age of leaf waxes in lake sediments. This project examines these two processes in temperate lakes in the Adirondack Mountains, NY, USA. Research methods will include forest inventorying, modern leaf wax (n-alkane and n-alkanoic acid) molecular and isotope (hydrogen, carbon) characterization, lake sediment coring and dating (210Pb, 137Cs, 14C), and compound-specific radiocarbonanalyses of n-alkanes in lake sediments, catchment soils, and fluvial suspended sediments. The project will benefit society by 1) establishing partnerships with St. Lawrence University, a primarily undergraduate institution, to develop interdisciplinary collaborations and undergraduate research opportunities, create graduate student mentoring opportunities, and provide a hands-on isotope workshop for undergraduates; 2) improving STEM field retention by providing research and training experiences for two undergraduate students per year to develop advanced research skill sets, expand scientific understanding, and strengthen preparation for graduate studies or a career in the geosciences; 3) increasing the number of women in STEM fields by support of a Ph.D. student and an undergraduate students; 4) providing mentoring to enhance the educational and career development of undergraduate and graduate students, and improving the success of mentoring approaches through regular assessment and professional development; and 5) promoting broader public understanding of the geosciences and appreciation of scientific research by expanding on museum exhibits in collaboration with the Cincinnati Museum of Center, a large urban cultural institution.

为了确定未来降水量可能如何变化，重要的是要有过去降水量变化的基线。然而，在生成仪器记录之前确定过去的降水量仍然具有挑战性，并且需要使用地质记录中保存的降水代理。生物代理，例如叶蜡，在这方面有希望，因为叶蜡的氢同位素组成主要反映了降水的氢同位素组成。因此，湖泊沉积物中保存的叶蜡是有关降水和水循环如何随地质时间变化的高分辨率信息的潜在来源。然而，现代叶蜡向湖泊沉积物的转移似乎导致了氢同位素值的偏移。该项目将帮助定义这些补偿并确定控制它们的因素，从而改进对过去水文条件的重建。在评估这些偏移并测量其影响之前，沉积叶蜡与降水之间的定量联系将仍然有限。识别这些因素将有助于选择这些偏移影响最小的湖泊。这对于在仪器记录之前限制过去的水文变化至关重要，并将有助于预测未来的水文变化。该项目将通过与主要本科院校圣劳伦斯大学的跨学科合作，为本科生创造教育和研究经验，从而造福社会。这将为本科生提供研究和培训经验，培养先进的研究技能，扩大科学理解，并加强研究生学习或地球科学职业的准备，从而提高 STEM 领域的保留率。最后，这项研究将通过与大型城市文化机构辛辛那提博物馆中心合作扩大博物馆展品，促进公众对地球科学的更广泛理解和对科学研究的欣赏。过去的降水仍然是量化的挑战。生物代理，例如叶蜡，在这方面有希望，因为叶蜡的氢同位素组成主要反映植物源水（即降水）。然而，从降水氢同位素组成推断的定量古水文学由于对控制叶蜡从植物到沉积物的来源、整合和运输的埋藏过程了解甚少而受到限制。该项目将解决我们对湖泊沉积物叶蜡的理解中的两个重大差距。首先，研究人员将确定植被邻近度如何影响湖泊沉积物中的叶蜡氢同位素信号。其次，他们将确定河流侵蚀对较旧叶蜡的再加工对湖泊沉积物中叶蜡的表观年龄的影响有多大。该项目研究了美国纽约州阿迪朗达克山脉温带湖泊的这两个过程。研究方法将包括森林清查、现代叶蜡（正烷烃和正烷酸）分子和同位素（氢、碳）表征、湖泊沉积物取芯和测年（210Pb、137Cs、14C）以及n的化合物特异性放射性碳分析。 -湖泊沉积物、流域土壤和河流悬浮沉积物中的烷烃。该项目将通过以下方式造福社会：1）与主要本科院校圣劳伦斯大学建立合作伙伴关系，发展跨学科合作和本科生研究机会，创造研究生指导机会，并为本科生提供同位素实践研讨会； 2) 每年为两名本科生提供研究和培训经验，以培养高级研究技能、扩大科学理解并加强研究生学习或地球科学职业的准备，从而提高 STEM 领域的保留率； 3) 通过博士学位的支持，增加 STEM 领域的女性人数。学生和本科生； 4）提供指导，以促进本科生和研究生的教育和职业发展，并通过定期评估和专业发展提高指导方法的成功率； 5) 通过与大型城市文化机构辛辛那提中心博物馆合作扩大博物馆展品，促进公众对地球科学的更广泛理解和对科学研究的欣赏。

项目成果

Centennial-scale age offsets of plant wax n-alkanes in Adirondack lake sediments

阿迪朗达克湖沉积物中植物蜡正烷烃的百年尺度年龄偏移

• DOI: 10.1016/j.gca.2021.02.022
• 发表时间: 2021-05
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Freimuth, Erika J.;Diefendorf, Aaron F.;Lowell, Thomas V.;Schartman, Anna K.;Landis, Joshua D.;Stewart, Alexander K.;Bates, Benjamin R.
• 通讯作者: Bates, Benjamin R.

Contrasting sensitivity of lake sediment n-alkanoic acids and n-alkanes to basin-scale vegetation and regional-scale precipitation δ2H in the Adirondack Mountains, NY (USA)

纽约州阿迪朗达克山脉湖泊沉积物正构烷酸和正构烷烃对盆地规模植被和区域规模降水 Ύ´2H 的敏感性对比

• DOI: 10.1016/j.gca.2019.08.026
• 发表时间: 2024-09-14
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: E. Freimuth;A. Diefendorf;T. Lowell;Benjamin R. Bates;Anna K. Schartman;B. Bird;J. L;is;is;A. Stewart
• 通讯作者: A. Stewart

Hydrogen isotopic composition (δ2H) of diatom-derived C20 highly branched isoprenoids from lake sediments tracks lake water δ2H

湖泊沉积物中硅藻衍生的 C20 高度支化类异戊二烯的氢同位素组成 (δ2H) 追踪湖水 δ2H

• DOI: 10.1016/j.orggeochem.2020.104122
• 发表时间: 2020-12-01
• 期刊: Organic Geochemistry
• 影响因子: 3
• 作者: M. Corcoran;A. Diefendorf;T. Lowell;E. Freimuth;Anna K. Schartman;Benjamin R. Bates;A. Stewart;B. Bird
• 通讯作者: B. Bird

Sedimentary n-alkanes and n-alkanoic acids in a temperate bog are biased toward woody plants

温带沼泽中沉积的正烷烃和正烷酸偏向于木本植物

• DOI: 10.1016/j.orggeochem.2019.01.006
• 发表时间: 2019-02-01
• 期刊: Organic Geochemistry
• 影响因子: 3
• 作者: E. Freimuth;A. Diefendorf;T. Lowell;G. Wiles
• 通讯作者: G. Wiles

Stable source of Holocene spring precipitation recorded in leaf wax hydrogen-isotope ratios from two New York lakes

纽约两个湖泊叶蜡氢同位素比值记录全新世春季降水的稳定来源

• DOI: 10.1016/j.quascirev.2020.106357
• 发表时间: 2020-07-15
• 期刊: Quaternary Science Reviews
• 影响因子: 4
• 作者: Anna K. Schartman;A. Diefendorf;T. Lowell;E. Freimuth;A. Stewart;J. L;is;is;Benjamin R. Bates
• 通讯作者: Benjamin R. Bates