Quaternary ecological responses and impacts of the Indian Ocean Summer Monsoon at Nam Co, Southern Tibetan Plateau
Quaternary ecological responses and impacts of the Indian Ocean Summer Monsoon at Nam Co, Southern Tibetan Plateau
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DOI：
10.1016/j.quascirev.2015.01.023
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发表时间：
2015-03-15
影响因子：
4
通讯作者：
Gleixner, Gerd
中科院分区：
文献类型：
--
作者：
Guenther, Franziska;Witt, Roman;Gleixner, Gerd
从末次冰期到现在的间冰期，即全新世，是气候和环境变化影响生态系统的一个重要时期。基于我们的古水文三角洲D指标，由于特定的生态阈值，除了气候变化之外，水生生物的信号滞后于陆地信号。水生生物的反应很大程度上取决于温度和相关的湖泊大小，以及pH值和营养物质的可用性。由于陆地植被对季风和气候系统变化的反应更快、更敏感，因此n-C-29的δ D和重建的入流信号是一个合适的IOSM代表。一般来说，不同气团的相互作用似乎主要是由太阳日照控制的。在全新世，高日照产生了大的陆-海压力梯度，伴随着强季风和最强的IOSM。我们的研究结果有助于阐明变化的IOSM，并说明湖泊系统的pH值、三角洲（13）长和三角洲N-15从末次冰期到全新世间冰期的显著变化。(C) 2015 Elsevier Ltd.版权所有。
The transition from the Last Glacial to the current Interglacial, the Holocene, represents an important period with climatic and environmental changes impacting ecosystems. In this study, we examined the interplay between the Indian Ocean Summer Monsoon (IOSM) and the Westerlies at lake Nam Co, southern Tibet to understand the climatic effects on the ecosystem. Different organic geochemical proxies (n-alkanes, glycerol dialkyl glycerol tetraethers, delta D, delta(13)Corg, delta N-15) are applied to reconstruct the environmental and hydrological changes on one of the longest available paleorecords at the Tibetan Plateau. Based on our paleohydrological delta D proxies, the aquatic signal lags the terrestrial one due to specific ecological thresholds, which, in addition to climatic changes, can influence aquatic organisms. The aquatic organisms' response strongly depends on temperature and associated lake size, as well as pH and nutrient availability. Because the terrestrial vegetation reacts faster and more sensitively to changes in the monsoonal and climatic system, the delta D of n-C-29 and the reconstructed inflow water signal represent an appropriate IOSM proxy. In general, the interplay of the different air masses seems to be primarily controlled by solar insolation. In the Holocene, the high insolation generates a large land-ocean pressure gradient associated with strong monsoonal winds and the strongest IOSM. In the Last Glacial period, however, the weak insolation promoted the Westerlies, thereby increasing their influence at the Tibetan Plateau. Our results help to elucidate the variable IOSM, and they illustrate a remarkable shift in the lake system regarding pH, delta(13)Corg and delta N-15 from the Last Glacial to the Holocene interglacial period. (C) 2015 Elsevier Ltd. All rights reserved.