Geochemical fingerprints of land use and fire regimes in the central Mongolian steppe

城市化从根本上改变了蒙古的游牧生活和环境。然而，在蒙古草原的心脏地带，城市人口集聚的供应是如何维持的，以及这是如何被周围的环境所携带的，这一点尚不清楚。因此，在我们的项目中，我们在古气候变化和城市兴衰的背景下研究了过去土地使用和火灾制度的历史。在地方范围内，我们将评估游牧家庭和城市家庭在特定时期的废物处理是否不同以及如何不同。基于我们将找到过去农业的证据的假设，我们将分析崩塌沉积物，以了解区域过程。最后，在调查湖泊沉积物岩心时，我们希望找到关于城市和非城市阶段如何与超区域火灾事件和木本植物扩张相关的信息。为了实现这些目标，我们利用长期存在于环境中的地球化学信号进行营养、同位素和生物标志物分析：为了定位有机废物，我们将检查不同的p型；此外，甾醇和胆汁酸提供了有关其来源的信息，例如来自人类或动物。为了寻找可能存在C4植物种植的证据，我们记录了土壤有机质的稳定同位素组成；通过木质素分析，我们区分了原始森林和非森林地区。黑碳和（甲基化）多环芳烃分析进行重建的制度。总的来说，我们将有助于更好地理解城市的供应是如何与环境和土地使用条件相关联的。

Urbanism has fundamentally changed pastoral nomadism and environment in Mongolia. However, it is not known how the supply of an urban population agglomeration was sustained at the heart of the Mongolian steppe and how this was carried by the surrounding environment. In our project we therefore investigate the history of past land use and fire regimes in the context of paleoclimatic change and the rise and fall of the cities. At local scale, we will evaluate whether and how waste disposal differed between nomadic and urban households at specific time periods. Based on the assumption that we will find evidence for past agriculture, we will analyze colluvial deposits in order to understand regional processes. Finally, when investigating lacustrine sediment-cores, we expect to find information on how urban and non-urban phases correlate with supra-regional fire events and woody plant expansions. To achieve these aims, we conduct nutrient, isotopic, and biomarker analyses with geochemical signals that reside in the environment over long periods of time: in order to localize organic waste, we will examine different P-forms; in addition, sterols and bile acids provide information about their origin, e.g., from humans or animals. For possible evidence of a cultivation of C4 plants, we record the stable isotope composition of soil organic matter; by lignin analyses we differentiate formerly forested and non-forested areas. Black carbon and (methylated) polycyclic aromatic hydrocarbon analyses are performed to reconstruct fire regimes. Overall, we will thus contribute to a better understanding of how the supply of the city was related to environmental and land use conditions.