青藏高原东南部巴松措现代沉积过程及其对气候变化的响应

湖泊沉积物是记录气候演化信息的重要载体之一，在探讨过去气候变化过程研究中发挥重要作用.然而，沉积物中的许多代用指标对气候的指示意义存在多解性，不同指标所反映的环境信息相互之间有时会存在矛盾.为了能够更准确地解读湖泊沉积物中指标所记录的环境变化信息，开展现代湖泊沉积物指标与环境之间的关系研究，深入探讨各指标对环境变化的响应机制尤为关键.本文选取青藏高原东南部巴松措湖泊表层沉积物作为研究对象，利用²¹⁰Pb与¹³⁷Cs比活度检测结果建立年代序列，对沉积物中粒度、磁化率、有机质含量等指标进行分析，揭示巴松措现代沉积过程.结合沉积物粒度端元组分分析结果，并将不同指标变化与林芝气象站所记录的数据资料进行对比，得出以下主要结论：该地区沉积物来源主要包括径流搬运的冰川碎屑物质和来自青藏高原南部、西南部上空悬浮于大气中的风成物质两部分；其中，通过风力搬运的物质输入主要集中在冬半年，受季节性风向及风速变化影响明显；径流受到冰雪融水与夏季降水的补给，因此通过径流搬运的物质输入量受到温度与降水综合影响；湖泊中磁性矿物碎屑的产生和输入主要受区域降水量影响的流域侵蚀速率变化控制，该湖泊沉积物磁化率波动可以有效的指示该地区降水量变化；沉积物中总有机碳含量和总氮含量变化主要反映湖泊自身初级生产力的变化，对区域温度变化的响应显著.

Modern sedimentary process of Lake Basomtso in the southeastern Tibetan Plateau and its response to climate change

Lacustrine sediment has been regarded as one of the most important archives for inferring information about past climate fluctuations, which presented significant palaeoclimate sequences at different time scales. Various proxies have been investigated to acquire signals of climate changes, which, however, does not always lead to consistent inferences. In order to acquire the information of reliable climate changes from lake sediments, we now intend to investigate the relationship between sedimentary proxies and environment parameters especially the climate changes, to explore how the proxies respond to environment change. Thus, we chose Lake Basomtso from the southeastern Tibetan Plateau as our study area considering the high sedimentation rate and rare human activities. Combined with the chronology based on measurements of ²¹⁰Pb and ¹³⁷Cs, grain size, magnetic susceptibility and organic matter content of the modern sediments from both sediment cores and traps were analyzed. The results were subsequently compared with modern meteorological data from Nyingchi Station. The sediment mainly consists of two parts:the aeolian transported materials during the winter time from the south and southwest of the Tibetan Plateau, which showed significant consistence with the regional wind speed; and the fluvial transported materials that influenced by the temperature (melting effect) and precipitation together. The fluctuation of magnetic susceptibility of lake sediment of Lake Basomtso mainly reflects the input of magnetic mineral, which is closely affected by the precipitation related erosion rate. Finally, the variation of total organic carbon, total nitrogen content generally showed a gradual increasing trend of lake primary productivity, which responds closely to the changes of temperature, especially the global warming process.