Seasonal Variation and Processing of Vascular Plant Organic Matter in Tropical Montane Catchments as Reflected by Riverine DOC Compositions

热带系统面临着来自发展中国家土地使用变化以及即将发生的气候变化的未知影响的越来越大的压力。河流溶解有机碳（DOC）的浓度和组成是陆地过程在时间尺度上与土地利用变化和气候变化相关的集成器。鉴于大多数热带河流由于位置偏远和基础设施有限而难以研究，本项目将利用波多黎各卢基略临界区观测站（CZO）现有的基础设施和正在进行的研究。 具体来说，研究人员将测量组成和浓度的生物标志物为高等植物，木质素衍生的酚类，在一年的过程中，从两条河流排水流域相似的植被，但对比岩性和侵蚀速率的目标特征的季节性，事件驱动，和流域差异DOC组成和浓度。结果将进行比较和对比，与一个类似的数据集从温带农业流域，调查分区效果，在低和高排放的水文流径的影响，并使用碳归一化的木质素产量作为端员DOC来源。该项目将有助于在这些河流内建立碳循环基线测量，因此社会影响将是提高理解敏感热带系统即将发生的气候和土地使用变化的能力。 此外，这是一个调查流域内的基本过程，很可能是概括到几乎任何DOC的研究河流，因此结果将对未来的研究产生广泛的影响。该项目的结果将在科学会议上提出，并发表在同行评审的期刊上。PI Hernes教授本科生和研究生课程，涵盖全球碳循环，气候变化和河流地球化学的各个方面，从该项目收集的数据将用于展示易受变化状态因素影响的重要过程。将积极的研究纳入课程大纲，增加了教师和学生的积极性，经常导致本科实习。一个这样的本科生从一组代表性不足的科学将参与样品的实验室分析，并将有机会在校园本科生研究论坛上介绍结果。结果将公布在研究网站上，数据将提供给与卢基略CZO相关的适当国家和国际数据库，以供广泛使用。

Tropical systems face increasing pressure from land-use change in developing countries as well as unknown effects of imminent climate change. The concentration and composition of riverine dissolved organic carbon (DOC) serves as an integrator of terrestrial processes on timescales relevant to land-use change and climate change. Whereas most tropical rivers are challenging to study due to their remote locations and limited infrastructure, this project will take advantage of existing infrastructure and ongoing studies in the Luquillo Critical Zone Observatory (CZO) in Puerto Rico. Specifically, the investigator will measure the composition and concentration of biomarkers for higher plants, lignin-derived phenols, on weekly samples over the course of one year from two rivers that drain catchments of similar vegetation but contrasting lithologies and erosion rates with the goal of characterizing seasonal, event-driven, and catchment differences in DOC composition and concentration. Results will be compare and contrasted with a similar dataset from a temperate agricultural watershed to investigate partitioning effects, the effects of hydrologic flowpaths during low and high discharge, and the use of carbon-normalized yields of lignin as an endmember for DOC sources. This project will help to establish carbon cycling baseline measurements within these rivers, hence the societal impact will be an increased ability to understand impending climate and land-use changes in sensitive tropical systems. In addition, this is an investigation of fundamental processes within watersheds that are likely to be generalizable to nearly any DOC studies on rivers, hence results will have broad impact toward future studies. Results from this project will be presented at scientific meetings and published in peer-reviewed journals. The PI, Hernes, teaches undergraduate and graduate classes that cover various aspects of the global carbon cycle, climate change, and river biogeochemistry, and data collected from this project will be used to demonstrate important processes that are susceptible to changing state factors. Incorporation of active research into course curriculums increases the enthusiasm of both the instructor and the students, frequently leading to undergraduate internships. One such undergraduate from a group under-represented in science will participate in the laboratory analyses of samples and will have the opportunity to present results at undergraduate research forums on campus. Results will be posted on research websites and data contributed to appropriate national and international data bases associated with the Luquillo CZO for widespread use.