生物产生的部分有机碳可以在高原冰冻圈的冰川或冻土中停留上千年(定义为“老碳”)。气候变暖引起的老碳释放可能成为冰冻圈高原湖泊外源有机碳的重要组成部分。老碳对湖泊的补贴可能促进生态系统中消费者的生长，但老碳在湖泊生物可利用碳源中所占的比例及其在食物网中的传递途径尚未得到深入研究。本项目以青藏高原湖泊—沉错为研究地点，以老碳对高原湖泊浮游动物碳源的贡献比例和碳流途径为研究核心，基于对沉错浮游甲壳动物群落结构的时空分布以及湖泊有机碳源充分调查的基础上，测定不同来源有机碳和浮游甲壳动物的稳定与放射性碳同位素，从而估算不同碳源（包括外源输入的老碳）对浮游甲壳动物碳源构成的贡献比例；通过分析浮游甲壳动物脂肪酸与有机碳源脂肪酸标志物特征，结合稳定碳同位素分析，揭示浮游甲壳动物利用有机碳的主要途径。研究结果有助于阐明老碳的转化途径，为进一步研究高原湖泊生态系统碳循环过程的驱动机制与变化趋势增加科学积累。

Ancient organic carbon is defined as the fraction of the organic carbon (OC) produced by organism which can stay on the plateau cryosphere glaciers or permafrost for thousands of years. Owing to climate warming, ancient OC could be released from ice-sheet, glacier and permafrost systems and exported into high mountain lakes, thus become an important carbon source of consumers. Few studies have explored the potential use of this ancient OC in lake food webs. We aim to investigate the properties of OC composition and planktonic crustaceans community structure in a high mountain lake (Lake Chencuo). We will assess the contribution ratio of ancient OC to carbon source of planktonic crustaceans by analyzing the natural abundance of radiocarbon and stable carbon isotopes of the consumers and different carbon sources. To elucidate the main pathways of zooplankton utilizing ancient OC, phospholipid fatty acids biomarkers and stable carbon isotopes of zooplankton and its carbon sources are to be analyzed. This work is valuable for revealing the environmental transformation pathways of ancient OC in lacustrine ecosystem. Furthermore, it will be helpful to enhance understanding the driven mechanism and the trend of carbon cycling in aquatic ecosystems.