大兴安岭火山湖Group I长链烯酮冷季节温标研究与过去2000年温度定量重建

定量重建过去2000年温度变化是揭示20世纪气候变暖归因问题的重要途径。但是目前众多古温度代用指标通常反映的是夏季或年平均温度，准确定量重建的过去2000年冷季节温度序列至今仍鲜见报道，限制了对该时期温度变化驱动机制的全面深入理解。最新研究表明，淡水湖中新型的Group I长链烯酮有着巨大的潜力定量重建冷季节温度变化。本项目拟以存在Group I长链烯酮的大兴安岭火山堰塞湖为研究对象，通过分析生长季节的长链烯酮及其母源DNA信息，查明Group I长链烯酮主要在冷季节产生的机制，明确反映的冷季节温度的准确时间并建立该地区长链烯酮温度转换方程。以此为基础，在沉积岩芯中利用Group I长链烯酮准确定量重建该地区高分辨率的过去2000年冷季节温度变化，查明十年至百年尺度上温度变化的主要驱动因素以及20世纪是否为最暖期，为揭示气候变暖机制及预估未来温度变化趋势提供重要的科学依据。

Quantitative temperature reconstructions of the last 2000 years provide important way for revealing the reasons of climate warming in the 20th century. However, many paleotemperature proxies commonly record the variations of summer or mean annual air temperatures, and reliable cold season temperature records of the last 2000 years are still lack, which limits our full understanding of the mechanism driving the temperature changes. The latest studies indicated that the novel Group I alkenones from freshwater lakes have great potential for quantitative reconstructions of cold season temperatures. In the proposed research, first, we aim to explore the environmental controls on major production of Group I alkenones in cold season by analyzing the alkenones and their producer DNA collected throughout the course of a growing season in the volcanic lakes of the Great Khingan Mountain. The modern sample analyses will also allow us to determine the accurate timing of highest sedimentary fluxes of Group I alkenones and establish alkenone-temperature calibration in this region. Based on the modern process research, we will quantitatively reconstruct high-resolution changes in cold season temperatures in the region during the past 2000 years, and address the key driving factors of the temperature changes. Our research proposal will improve our understanding of forcing mechanisms of climate warming, and help the accurate projection of temperature change trend in the future.