| 引用本文: | 张延利,毛春晖,张家武,黄小忠,OtgonbayarDemberel.蒙古西北部Tolbo湖沉积物粒度敏感组分记录的全新世风沙活动.湖泊科学,2023,35(1):368-380. DOI:10.18307/2023.0129 |
| Zhang Yanli,Mao Chunhui,Zhang Jiawu,Huang Xiaozhong,Otgonbayar Demberel.Aeolian activities in the NW Mongolia during the Holocene recorded by grain-size-sensitive particles in the sediments of Lake Tolbo. J. Lake Sci.2023,35(1):368-380. DOI:10.18307/2023.0129 |
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| 摘要: |
| 作为全球主要的粉尘源区之一,亚洲中部干旱区全新世环境变化备受关注,但目前仍缺乏连续的风成沉积记录。本文利用蒙古西北部Tolbo湖岩芯(TB19-A,332 cm)沉积物,在AMS14C定年和粒度分析基础上,采用对数正态分布函数拟合及粒级-标准偏差相结合的方法分离出沉积物中风成组分以重建区域风沙活动历史。结果显示,Tolbo湖沉积物中值粒径为15~84 μm和大于84 μm的组分分别是区域尘暴和局地风沙活动的良好指标。蒙古西北部地区末次冰消期晚期(13.75—11.6 cal ka BP),Tolbo湖流域内有较强的局地风沙活动,可能与YD寒冷事件有关。全新世以来,流域内局地风沙活动与蒙古西北部区域尘暴活动的变化具有一致性,具体表现为:早中全新世风沙活动总体较弱,其中9.7—8.6 cal ka BP和7—6 cal ka BP为区域尘暴较强时段;5 cal ka BP之后局地风沙活动与区域尘暴强度显著增加,直至0.7 cal ka BP两者均维持在较高水平;0.3 cal ka BP以来区域尘暴活动再次增强。蒙古西北部与中国北方公海、博斯腾湖记录的尘暴历史具有一致的变化趋势,反映了与西伯利亚高压相联系的大气环流对于干旱区大范围风沙活动的影响。晚全新世风沙活动的增强可能还与冬季太阳辐射的增加有关,最近300年来强烈的区域尘暴活动除了自然因素外,可能还叠加了人类活动的影响。 |
| 关键词: 粒度分析 尘暴 西伯利亚高压 大气环流 冬季太阳辐射 |
| DOI：10.18307/2023.0129 |
| 分类号: |
| 基金项目:国家重点研发计划项目(2017YFA0603402)、国家自然科学基金项目(41771212)和兰州大学西部环境教育部重点实验室开放基金及兰州大学中央高校基本业务费专项资金(lzujbky-2021-kb01)联合资助。 |
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| Aeolian activities in the NW Mongolia during the Holocene recorded by grain-size-sensitive particles in the sediments of Lake Tolbo |
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Zhang Yanli1, Mao Chunhui1, Zhang Jiawu1, Huang Xiaozhong1, Otgonbayar Demberel2
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1.Key Laboratory of Western China's Environmental Systems, Ministry of Education, College of Earth Environmental Sciences, Lanzhou University, Lanzhou 730000, P. R. China;2.Institute of Natural Science and Technology, Khovd State University, Khovd 84000, Mongolia
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| Abstract: |
| As one of the major dust source areas of the world, the arid central Asia has recently attracted much attention in environmental changes during the Holocene. However, continuous sedimentary records of the history of aeolian activities are lacking in this region. Here we report a sedimentary record of regional aeolian activities using a sediment core from Lake Tolbo (TB19-A, 332 cm-long) in the NW Mongolia. The core was dated using AMS14C and the reservoir effect was assessed for the chronology. Lognormal distribution function fitting and grain size-standard deviation methods were employed to extract the aeolian components in the sediments from the grain size data of the sedimentary sequence. The history of aeolian sand activities or dust storms in the NW Mongolia was then reconstructed. The results show that fractions with the median grain size of 15-84 μm and >84 μm in the sediments from Lake Tolbo can be used as indicators of regional dust storms and local aeolian sand activities, respectively. At the late Last Deglacial (13.75-11.6 cal ka BP), there were strong local aeolian sand activities in the basin, which may be related to the YD cold events. Since Holocene, the changes of the local aeolian sand activities in the basin were consistent with the regional dust storms in the NW Mongolia, which can be shown as follows: during the early and middle Holocene, aeolian sand activities were generally weak, and relatively strong regional dust storms occurred during the periods of 9.7-8.6 cal ka BP and 7-6 cal ka BP. After 5 cal ka BP, local aeolian sand activities and regional dust storms intensified significantly, and both were at high levels until 0.7 cal ka BP. Extremely strong regional dust storms occurred in the past 0.3 cal ka BP. The dust storm history in the NW Mongolia is similar to those documented in Lake Gonghai in northern China and Lake Bosten in the NW China, reflecting the influence of the atmospheric circulation associated with the Siberian High on large-scale aeolian activities in arid regions. The increase of winter insolation may have also strengthened the aeolian activities during the late Holocene. The strong regional dust storms in the past 300 years may have been compounded by human activity in addition to the natural factors. |
| Key words: Grain size analysis dust storm Siberian High atmospheric circulation winter insolation |
