Collaborative Research: Stabilized Organic Carbon and Paleoenvironmental Interpretations of Late Quaternary Paleosols

michael Thompson，爱荷华州立大学，稳定有机碳与晚第四纪古土壤的古环境解释elmer Bettis III，爱荷华大学，earr - 1226412rolfe Mandel，堪萨斯大学，earr -1226757 Mao jingdong， Old Dominion大学，earr -1226323摘要古土壤是广泛的古环境信息档案。许多第四纪古土壤横向分布广泛，容易相互关联，并提示区域气候或地貌稳定的时期。这笔拨款的重点是古土壤中的有机质（OM）。本基金的目标是：(1)在千年尺度上确定有机质稳定机制的重要性并对其进行排序；(2)显著改进中大陆、晚第四纪环境的古植被重建。在堪萨斯州和内布拉斯加州的五个地点，OM将在44.6 ka的埋藏古土壤中进行研究。选择这些古土壤是为了(1)表征中大陆两种最广泛的表层物质（冲积层和黄土）中的古土壤有机质；(2)比较主要曝气条件下的有机质（黄土土）与曝气和饱和交替条件下的有机质（冲积土）；(3)系统延长有机质埋藏期，为早期成岩作用的发生创造条件；(4)利用从以前的研究中获得的信息。这个项目将提高对土壤有机质的哪些成分在千年时间尺度上被保存下来以及它们为什么被保存下来的理解。这样的理解将为基于om托管代理的第四纪古环境和景观的重建提供信息。特别令人感兴趣的是一种假设，即古土壤中稳定碳的重要组成部分是由木炭组成的。通过评价炭在古土壤有机质中的意义，可以阐明火在古土壤碳储量、景观演化和古气候解释中的作用。由于某些形式的有机质将矿物颗粒结合在一起，古土壤有机质成分可能调节沉积物抵抗侵蚀的能力，从而影响景观演变。这项研究还将有助于完善地球化学模型，预测土壤中有效封存的碳量，并为陆地有机质的长期稳定性及其对全球碳循环的影响提供新的见解。该项目将通过与阿拉巴马州农工大学的同事和学生的合作，扩大在地球科学领域代表性不足的群体的参与。作为ISU乔治·华盛顿·卡弗暑期实习计划的一部分，AAMU的学生将被邀请在夏季会议期间加入研究团队，他们将被招募到爱荷华州立大学和爱荷华大学进行研究生学习。

Collaborative Research: Stabilized Organic Carbon and Paleoenvironmental Interpretations of Late Quaternary PaleosolsMichael Thompson, Iowa State University, EAR-1226949Elmer Bettis III, University of Iowa, EAR-1226412Rolfe Mandel, Kansas University, EAR-1226757Jingdong Mao, Old Dominion University, EAR-1226323ABSTRACTPaleosols are widespread archives of paleoenvironmental information. Many Quaternary paleosols are laterally extensive, readily correlated, and suggestive of periods of regional climatic or geomorphic stability. This grant focuses on organic matter (OM) in paleosols. The objectives of this grant are (1) to identify and rank the importance of mechanisms of OM stabilization at the millennial scale, and (2) to significantly refine paleovegetation reconstructions of midcontinent, Late-Quaternary environments. At five sites in Kansas and Nebraska, OM will be studied in buried paleosols as old as 44.6 ka. These paleosols were chosen (1) to characterize paleosol organic matter in the two most widespread surficial materials in the Midcontinent (alluvium and loess), (2) to compare OM that has witnessed primarily aerated conditions (loess soils) with OM that has been subjected to alternating aerated and saturated condition (alluvial soils); (3) to systematically lengthen the periods in which OM has been buried, giving opportunity for early diagenetic changes to occur; and (4) to capitalize on information available from previous studies.This project will improve understanding of which components of soil organic matter are preserved over millennial time scales and why they are preserved. Such understanding will inform reconstructions of Quaternary paleoenvironments and landscapes that are based on OM-hosted proxies. Of particular interest is the hypothesis that a significant component of stable carbon in paleosols consists of charcoal.By evaluating the significance of charcoal in paleosol OM, the roles that fire can play in carbon storage, landscape evolution, and interpretations of paleoclimate can be elucidated. Because some forms of OM bind together mineral particles, paleosol OM components may regulate the ability of sediments to resist erosion, thus impacting landscape evolution. The research will also help to refine geochemical models that predict the amount of carbon that can be effectively sequestered in soils and provide new insights concerning the long-term stability of terrestrial OM and its impact on global carbon cycles.This project will broaden participation of underrepresented groups in earth sciences through collaboration with colleagues and students at Alabama A&M Univ. AAMU students be invited to join the research team during summer sessions as part of ISU's George Washington Carver Summer Internship program and they will be recruited for graduate studies at Iowa State Univ. and Univ. of Iowa.