Freshwater aquatic systems are subjected to rapid deterioration driven by multiple stressors such as climate change and human activity. The understanding of the long-term history of eutrophication and their trends provides an opportunity for developing relevant management strategies. In this study, we examine the natural versus anthropogenic impacts on Ahansar Lake using a multiproxy approach (total organic carbon (TOC), total nitrogen (TN), amino acid composition, δ¹⁵N, grain size and pollen data) on a²¹⁰Pb/¹³⁷Cs dated sediment core spanning the last 200 years. The amino acid datasets clearly show that the organic matter in Ahansar sediment core is less degraded and can be utilized to understand the paleoproductivity changes. Organic matter (OM) within this core is mostly derived from aquatic sources as deduced from C/N (6–11) and δ¹⁵N (0–3.2‰) values. The aquatic productivity gradually increases from 1880s, becoming accelerated after the 1930s, and peaked between 1970 and 2016 AD. This enhancement of primary productivity in the lake indicating the increased eutrophication through time due to anthropogenic activities in the recent decades. The results provide baseline information for policymakers and environmentalists to develop strategical framework for future environmental changes in an aquatic system subjected to anthropogenic stressors.

淡水水生系统在气候变化和人类活动等多重压力的推动下迅速恶化。了解富营养化的长期历史及其趋势为制定相关管理策略提供了机会。在这项研究中，我们使用多代理方法（总有机碳 (TOC)、总氮 (TN)、氨基酸组成、δ ¹⁵ N、晶粒大小和花粉数据）对²¹⁰ Pb / ¹³⁷过去 200 年的 Cs 年代沉积岩心。氨基酸数据集清楚地表明，Ahansar 沉积物核心中的有机质降解较少，可用于了解古生产力变化。根据 C/N (6–11) 和 δ ¹⁵推断，该核心内的有机质 (OM) 主要来自水生来源N (0–3.2‰) 值。水产生产力从 1880 年代开始逐渐增加，1930 年代以后加快，并在公元 1970 年至 2016 年达到顶峰。湖泊初级生产力的这种提高表明，由于近几十年来的人为活动，随着时间的推移，富营养化程度不断提高。结果为政策制定者和环保主义者提供了基线信息，以制定应对人为压力源的水生系统未来环境变化的战略框架。