长链烯酮不饱和度是定量重建古温度变化的重要替代指标，但湖泊中不同母源种属对温度的响应不一致，干扰了该指标对陆地古温度的定量重建。重要的是，目前DNA数据表明淡水湖中长链烯酮的母源GroupⅠ是基因高度相似的同一种系，尽可能避免了不同种属的影响（Longo et al., 2016）。我们最新在我国东北地区火山湖（淡水湖）的初步研究发现，该类湖泊中存在GroupⅠ类型的长链烯酮，为该地区古温度的定量重建提供了可能。为此，本研究拟将系统调查东北地区火山湖中的长链烯酮分布及其母源信息，探究GroupⅠ类型的长链烯酮的出现和分布的主要影响因素，同时利用“器测校正”方法在沉积速率高的五大连池二池建立GroupⅠ的烯酮-温度转化方程，定量重建该地区短时间尺度下的温度变化。这将不仅提高对GroupⅠ定鞭藻生长环境及其长链烯酮指标的认识，也为该地区长时间尺度的古温度定量重建提供理论基础。

Alkenone unsaturation indices are important proxies for quantitative paleotemperature reconstructions. However, individual lakes may harbor multiple alkenone-producing haptophyte species with different temperature responses, confounding quantitative reconstructions for continental paleotemperature. Importantly, recent genetic data indicate that alkenone-producing Group Ⅰ haptophytes occurring in freshwater lakes occupy a common phylogenetic clade with high genetic similarity, and their long-chain alkenones (LCAs) may elude species effects (Long et al., 2016). Our recent preliminary study found that there were Group Ⅰ-type LCAs in the volcanic lake (freshwater lake) of northeastern China, indicating that these lakes are highly valuable targets for quantitative paleotemperature reconstructions. In this project, we will systematically investigate the LCAs distributions and identify their producers from the volcanic lakes of northeastern China, to explore the main control factors for the occurrence and distribution of Group Ⅰ-type LCAs. Moreover, we will take advantage of the exceptionally high sedimentation rate of Wudalianchi to establish Group Ⅰ alkenone-temperature calibration to instrumentally recorded temperature, and will extend the record to beyond the instrumental data. Our research will not only improve the understanding of growing conditions for Group Ⅰhaptophytes and their alkenone proxies, but also provide the theoretical basis for quantitative paleotemperature reconstruction at long-time scale in this region.