Application of a Diatom Transfer Function to Quantitative Paleoclimatic Reconstruction — A Case Study of Yunlong Lake, Southwest China
Application of a Diatom Transfer Function to Quantitative Paleoclimatic Reconstruction — A Case Study of Yunlong Lake, Southwest China
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DOI：
10.3389/feart.2021.700194
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发表时间：
2021-06
期刊：
影响因子：
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通讯作者：
Y. Zou;Luo Wang;Haibo He;Guangxin Liu;Jiaoyang Zhang;Yaozu Yan;Z. Gu;Hongbo Zheng
中科院分区：
文献类型：
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作者：
Y. Zou;Luo Wang;Haibo He;Guangxin Liu;Jiaoyang Zhang;Yaozu Yan;Z. Gu;Hongbo Zheng
尽管湖泊沉积物中的硅藻记录已被用于定量古气候重建，但其有效性和敏感性很少受到严格的检验。在中国西南高山湖泊云龙湖，我们研究了硅藻组合的季节演替，以产生一个平均表面水温（MSWT）的转换函数。此外，基于硅藻组合随水深的空间分布，建立了硅藻-水深（WD）转换函数。结合YL 2013-A沉积物柱样硅藻组合分析，利用基于转换函数的方法定量重建了近100年来表层水温和水位的变化。通过与区域气象资料和水库蓄水量资料的对比分析发现，以长江流域为基础的湖泊水位重建是降水短期波动的敏感指标，同时也反映了水库蓄水和大规模扩建引起的水位长期阶段性上升。此外，该模型推断的MSWT与场地大规模人为干扰前的气温变化一致。但水库扩建后，虽然区域气温持续升高，但水温大幅下降。这表明，短期内湖泊水量的大幅增加导致平均水温下降，进而导致冷季硅藻水华的发生。结果表明，基于同一湖泊现代观测资料的硅藻传递函数具有较高的环境敏感性，可用于区域气候变化的定量重建。总体而言，我们的研究结果提供了一个基础，利用湖泊硅藻记录定量古气候重建在不同的时间尺度。
Although diatom records from lake sediments have been used for quantitative paleoclimatic reconstruction, their validity and sensitivity have rarely been tested rigorously. At Yunlong Lake, an alpine lake in Southwest China, we studied the seasonal succession of diatom assemblages to produce a mean surface water temperature (MSWT) transfer function. In addition, based on the spatial distribution of surface diatom assemblages with water depth, we produced a diatom-water depth (WD) transfer function. Combined with the analysis of diatom assemblages in a sediment core (YL2013-A), changes in surface water temperature and water level over the last ∼100 years were quantitatively reconstructed using the diatom-based transfer functions. Comparison with records of regional meteorology and reservoir water capacity revealed that the diatom-based lake water level reconstruction is a sensitive indicator of short-term fluctuations in precipitation, and it also reflects a long-term stepwise rise in water level caused by the impounding and large-scale extension of the reservoir. In addition, the diatom-inferred MSWT is consistent with the changes in air temperature prior to large-scale human disturbance of the site. However, after the extension of the reservoir, although the regional air temperature continued to increase, the water temperature decreased substantially. This suggests that the large increase in lake water volume in the short term led to a decrease in the average water temperature, which in turn led to the occurrence of a diatom bloom in the cold season. The results demonstrate that diatom transfer functions based on modern observations of the same lake has a high environmental sensitivity and can be used for the quantitative reconstruction of regional climate change. Overall, our findings provide a foundation for the use of lake diatom records for quantitative paleoclimatic reconstruction on various timescales.