Isotopic Records in Post-Glacial Lake Sediments: Implications for Biota and Landscape Evolution

湖泊沉积物提供了受环境和气候变化影响的地表和湖泊过程的时间记录。由于环境变化影响湖泊及其周围的生物群落，因此可以在其沉积物中保存的有机物质的化学成分中找到当地和区域环境历史的证据。与冰期-间冰期过渡相关的极端气候变化对湖泊沉积物产生了深刻的生态影响。该项目的目的是了解湖泊生态系统是如何以及以什么速率在新形成的冰川后湖泊中建立起来的，并调查湖泊生态系统与流域演变之间的关系。为了实现这些目标，我们将从新英格兰的冰期后湖泊中收集整个晚更新世-全新世的沉积物岩心。对沉积有机质特征的分析包括：碳氮稳定同位素、有机碳氮含量、碳氮比、氢氧指数。现在的流域和湖泊植物的样本也将被收集到每个核心湖泊。这一现代数据集将为沉积记录的解释提供基础。拟议的研究具有重大的潜在影响。如果像假设的那样，由碳同位素提供的地球化学记录反映了发展中的湖泊系统对当地地质、水文和生物群的个体响应，那么在尝试在地方、区域和全球尺度上进行环境气候代理的相关性之前，必须考虑这些因素。研究结果还将限制湖泊生态系统从极端自然或人为干扰中恢复所需的时间。

Lake sediments provide a temporal record of surface and lacustrine processes influenced by environmental and climatic changes. Since environmental changes affect the biological communities in and around lakes, evidence of local and regional environmental histories can be found in the chemical composition of organic material preserved in their sediments. The extreme climatic changes associated with glacial-interglacial transitions had profound ecological impacts, which are recorded in lake sediments. The objectives of this project are to understand how and at what rates lacustrine ecosystems were established in newly created post-glacial lakes, and to investigate the relationship between lake ecosystem and watershed evolution. In order to meet these objectives, sediment cores spanning the whole late Pleistocene-Holocene time interval will be collected from post-glacial lakes in New England. Analyses that will be performed to characterize the sedimentary organic matter include: carbon and nitrogen stable isotopes, organic carbon and nitrogen content, C/N ratios, and hydrogen and oxygen indices. Samples of present-day watershed and lake plants will also be collected for each of the cored lakes. This modern dataset will provide a base for the interpretation of the sedimentary records. The proposed study has significant potential impacts. If, as hypothesized, geochemical records such as those provided by carbon isotopes reflect the individualistic response of the developing lake systems to the local geology, hydrology, and biota, these factors must be considered before attempting correlation of environmental climate proxies on a local, regional, and global scale. Results will also provide constraints on how much time is needed for lake ecosystems to recover from extreme natural or anthropogenic disturbances.