| H1事件时长江下游地区季风降水变化特征的石笋铀元素记录 |
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| 引用本文： | 周汪洋,段福才,陈剑舜,朱丽东,李凤全,王天阳.H1事件时长江下游地区季风降水变化特征的石笋铀元素记录[J].沉积学报,2021,39(4):932-941. |
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| 作者姓名： | 周汪洋 段福才 陈剑舜 朱丽东 李凤全 王天阳 |
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| 作者单位： | 浙江师范大学地理与环境科学学院，浙江 金华 321004 |
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| 基金项目： | 浙江省自然科学基金LY19D020001, LY16D010001国家自然科学基金41602182, 41971111, 41572345 |
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| 摘 要： | Heinrich 1（H1）事件是末次冰期向全新世转变过程中，北高纬大冰盖快速崩塌的冰盖不稳定事件，其气候环境影响深远。东亚地区石笋δ18O记录在H1事件时，普遍正偏至冰期的较大值，此正偏值通常指示东亚季风整体减弱。然而，在长江中游地区反映局地水文变化的石笋微量元素和碳同位素记录，显示在H1事件时梅雨量增加。梅雨与东亚季风强度的反相关关系是否存在，这有待更多记录的验证与支持。基于长江下游梅雨区南京葫芦洞石笋铀元素的水文变化特征，发现在H1事件时，梅雨整体增多。在H1事件内部结构特征上，高分辨率石笋δ18O记录显示，以~16.1 ka B.P.为界，东亚季风强度存在两个不同状态，类似的转变过程在铀元素记录中有所体现，表现为梅雨量由低到高的转变特征。石笋δ18O记录的这一季风强度变化过程在20年内完成，铀元素记录尽管分辨率不高，但也表现为快速转变的特征。这种对应的快速转变过程，表明石笋铀元素对东亚季风大气环流变化的积极响应；另一方面，也证实了铀元素对气候环境变化的有效记录。南京葫芦洞石笋铀元素记录了梅雨在长江下游地区H1事件期间增强的特征，进一步支持了梅雨与季风强度变化的反相关关系，提供了中国季风区降水空间差异的东部记录。
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| 关 键 词： | Heinrich 1事件 梅雨 δ 234UInitial值 238U浓度 季风强度 |
| 收稿时间： | 2020-01-06 |
Variations in Monsoonal Precipitation in the Lower Reaches of the Yangtze River During the H1 Indicated by Stalagmite Uranium Element from Hulu Cave,Nanjing, China |
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| ZHOU WangYang,DUAN FuCai,CHEN JianShun,ZHU LiDong,LI FengQuan,WANG TianYang.Variations in Monsoonal Precipitation in the Lower Reaches of the Yangtze River During the H1 Indicated by Stalagmite Uranium Element from Hulu Cave,Nanjing, China[J].Acta Sedimentologica Sinica,2021,39(4):932-941. |
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| Authors: | ZHOU WangYang DUAN FuCai CHEN JianShun ZHU LiDong LI FengQuan WANG TianYang |
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| Institution: | College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China |
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| Abstract: | The Heinrich 1 （H1） event was an extremely cold period when the northern ice sheet at high latitudes rapidly collapsed during the transition from the last glaciation to the Holocene. This event influenced global climate widely. Stalagmite δ18O records in the East Asian monsoon domain shifted to a heavier value and indicated weakened East Asian summer monsoonal intensity during the event. Stalagmite trace element and carbon isotope records both reflect hydrological variations at the cave site， and they indicated increased Meiyu rainfall in the middle reaches of the Yangtze River during the H1. This finding indicates an anti?phased relationship between Meiyu rain and East Asian summer monsoonal intensity. This relationship is further supported by a new Hulu record as suggested in this study. The stalagmite uranium element record in Hulu Cave indicated increased Meiyu rain in the lower reaches of the Yangtze River during the H1 event. In terms of the internal structure of the H1 event， previous high?resolution stalagmite δ18O records have depicted two different phases of the intensity of East Asian summer monsoons at the boundary of ~16.1 ka B.P. within the H1. A similar structure is also recorded in our uranium element data， with the increase in Meiyu rainfall corresponding to weakened East Asian summer monsoonal intensity. Higher?resolution stalagmite δ18O records suggest that the shift at ~16.1 ka B.P. ceased within 20 years. Although of a lower resolution， the uranium element records also indicate that the corresponding change in the Meiyu rain was rapid. These observations reveal that the uranium element responded positively to the East Asian monsoon circulation， and they support the supposition that uranium element is a valuable indicator of climate change. In sum， the increased Meiyu rain in the lower reaches of the Yangtze River documented by the Hulu uranium element data further supports the inverse relationship between the Meiyu rain and monsoonal intensity during the H1 event. Furthermore， our records point to a spatial discrepancy in monsoonal precipitation in Eastern China. |
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