Mid and Late Holocene climate and environmental history based on lipid biomarkers from Moossee, Switzerland

欧洲阿尔卑斯山对人类活动和气候变化非常敏感。在全球变暖时期，可以观察到快速变化的水文气候，伴有强降雨事件、严重的夏季干旱和缺水。这将增加更频繁的洪水和森林火灾的风险。为了更好地理解气候与景观的相互作用，以及为了未来的预测和风险评估，需要对过去气候和环境动态进行强有力的重建。在对全新世植被史和温度变化有充分了解的同时，多项研究表明，水文气候具有强烈的时空变异性。洪水记录和湖泊水位重建提供了有价值的信息，但并不是所有与生态相关的方面，如蒸散发，都能在高时间分辨率下覆盖。此外，要理清各种影响，即温度和降水，以及人为影响，并非总是微不足道的。毕竟，自7000年前新石器时代开始，人类活动就大大增加了。在过去的几年里，几种生物标志物方法已经可用，可以独立地重建水文和人类影响。它们在世界范围内的应用越来越广泛，但到目前为止，还没有结合各种脂质生物标志物及其化合物特异性同位素组成的高分辨率记录。该项目的目的是促进对欧洲阿尔卑斯山的水文气候、环境和人类历史的进一步了解。因此，脂质生物标志物方法将在瑞士Moossee湖沉积物中得到验证和应用。穆西是古环境重建的关键地点，因为考古证据（桩式住宅）记录了自新石器时代以来人类的存在。沉积物是多样的，年代非常准确，我们可以建立一个连续的高分辨率植被，地球化学和木炭记录。详细地说，我们将利用水生和陆生正烷烃的化合物特异性δ2H在高时间（30年）分辨率下重建全新世中晚期的湖泊水分蒸发（目标2）。为了确保可靠的解释，我们首先分析了现代植物和表土的正构烷烃模式和化合物特定的δ2H组成（目标1）。此外，我们应用多环芳烃来重建过去的火灾动态和粪便生物标志物（固醇和胆汁酸），以检测牲畜的变化（目标3）。这补充了现有的木炭和花粉记录，因为它有助于进一步研究人类对古火的影响，甚至可能在穆西考古发现的背景下研究文化进步。我们的多脂生物标志物方法是此类方法中的第一个，将为欧洲阿尔卑斯山的气候和人类历史提供有价值的见解。

The European Alps are highly sensitive to human impact and climate change. At times of global warming, a rapidly changing hydroclimate with heavy rainfall events, severe summer droughts and water scarcity can be observed. This will increase the risk of more frequent floods and forest fires. Robust reconstructions of past climate and environmental dynamics are needed to better understand climate-landscape interactions, and for future projections and risk assessments. While the vegetation history and temperature changes during the Holocene is well understood, multiple studies indicate strong spatio-temporal variability regarding the hydroclimate. Flood records and lake level reconstructions provide valuable information, yet not all ecologically relevant aspects, like evapotranspiration, are covered at high temporal resolution. Moreover, it is not always trivial to disentangle various influences, i.e. temperature and precipitation, but also anthropogenic effects. After all, anthropogenic activity increased a lot with the onset of the Neolithic ~7000 years ago. Over the last few years, several biomarker methods have become available, allowing to reconstruct hydrology and human impact independently. They are increasingly applied world-wide, yet no high-resolution records combining various lipid biomarkers and their compound-specific isotopic composition are available for the Alps and their forelands so far. The aim of this project is to contribute to an improved understanding of the hydroclimate, environmental and human history in the European Alps. Therefore, lipid biomarker methods will be validated and applied for lake sediments from Moossee, Switzerland. Moossee is a key site for paleoenvironmental reconstructions, because archaeological evidence (pile dwellings) documents the presence of humans since the Neolithic. The sediments are varved and extraordinarily well-dated, and we can build on a continuous high-resolution vegetation, geochemical and charcoal record. In detail, we will reconstruct lake water evaporation during the Mid and Late Holocene at high temporal (30 yr) resolution using compound-specific δ2H of aquatic and terrestrial n-alkanes (Objective 2). To ensure robust interpretation, we first analyse modern plants and topsoils for their n-alkane pattern and compound-specific δ2H composition (Objective 1). Moreover, we apply polycyclic aromatic hydrocarbons to reconstruct past fire dynamics and fecal biomarkers (sterols and bile acids) to detect changes in livestock (Objective 3). This complements the existing charcoal and pollen record, because it helps to further investigate anthropogenic influences on paleofires and possibly even cultural advances in context of archeological findings at Moossee. Our multi-lipid biomarker approach is the first of this kind and will provide valuable insights into the climate and human history of the European Alps.