|基于沉积序列重建古气候环境是研究全球变化的基础性工作。优选指标应该是各类指标体系中的敏感参数。但是, 各种环境背景变化会模糊其敏感程度, 使重建结果失真。我们创建了一个包含17个参数的粒度系统, 由此提供的粒度异常指数对位于东亚季风区农牧交错带的封闭湖泊黄旗海百余年湖面波动进行了定量重建。结果表明: 异常指数与湖面波动具有非常敏感的相关关系, 其敏感程度远高于普通粒度指标。1885~1895年和1950~1985年间为黄旗海高湖面阶段, 1895~1950年和1985~2010年间为低湖面阶段。这一结果与沉积相、流域降水记录、遥感及文献记录显示的结果一致。不过, 对1990~2010年而言, 粒度异常指数与湖面波动并不相关, 表明这个阶段的湖面升降原因复杂, 明显是受到了人类活动, 如拦河筑坝、开采地下水等的干扰。本研究创建了基于沉积物粒度异常指数定量重建封闭湖泊湖面波动历史, 对研究全球气候变化提供了方法学参考。
|关键词: 黄旗海 湖泊沉积 粒度异常指数 湖面波动
|QUANTITATIVE RECONSTRUCTION OF LAKE LEVEL FLUCTUATION IN HUANGQIHAI FROM 1885 TO 2010 BASED ON GRAIN SIZE ANOMALY INDEX FROM HQH4 CORE SEDIMENT
JIA Yu-Lian1, ZHOU Shu-Jin1, WANG Peng-Ling2, WAN Zhi-Wei3, LING Chao-Hao1, SHEN Hong-Yuan4
1.School of Historical Geography, Minnan Normal University, Zhangzhou 363000, China;2.National climate center, Beijing 100866, China;3.School of Geography and Environment, Jiangxi Normal University, Ganzhou 341000, China;4.College of Resources and Environment, Linyi University, Linyi 276000, China
|Reconstructing the paleoclimate environment based on sedimentary sequences is a basic task in studying global change. The preferred indicators should be sensitive parameters in various indicator systems. However, various environmental background changes will blur its sensitivity and distort the reconstruction results. We created a 17-parameter grain size index system to develop grain size anomaly indexes to quantitatively reconstruct the lake level fluctuations of Huangqihai (Huangqi Lake), a closed lake located in the agro-pastoral ecotone of the East Asian monsoon region from 1885 to 2010. Results show that the anomaly index has a very sensitive correlation with lake surface fluctuations, and its sensitivity is much greater than that of ordinary particle size indicators. The years 1885~1895 and 1950~1985 were the high lake level stage of Huangqihai, and the years 1895~1950 and 1985~2010 were the low lake level stage. This result is consistent with the results revealed by sedimentary facies, basin precipitation records, remote sensing, and literature records. However, for the years 1990~2010, the particle size anomaly index was not related to the lake level fluctuations, indicating that the reasons for the rise and fall of the lake level at this stage were complex and obviously disturbed by human activities, such as river damming and groundwater extraction. This study created a quantitative method to reconstruct the lake surface fluctuation history of closed lakes based on the sediment particle size anomaly index, which provided a reference for studying global climate change.
|Key words: Huangqihai lake sedimentation grain size anomaly index lake surface fluctuation