摘要
长江下游地区是我国受东亚季风影响的典型区域, 已有的过去气候变化研究更多侧重于对该区域的水文气候变化重建及其与人类活动关系的探讨, 而对于近千年以来温度变化及机制的认识仍相对薄弱。本研究选取长江下游升金湖86 cm长的沉积岩芯为研究对象, 经过14C分析该岩芯覆盖了过去千年的沉积信息;并将该岩芯分成了37个样品进行甘油二烷基甘油四醚类化合物(GDGTs)的测试与分析, 通过区域对比明确升金湖支链GDGTs (brGDGTs)来源;另外, 选择适用于该湖的brGDGTs温度校正公式, 重建了升金湖流域过去千年以来的温度变化并探讨其驱动机制。结果表明: 升金湖地区千年以来温度变化在现代暖期之前整体呈波动下降趋势;最高温度出现在中世纪暖期, 而不是在当前暖期;此外, 升金湖重建的温度变化与周围较大的空间尺度上的结果具有较好的一致性。根据重建温度结果, 将过去千年该地区温度变化划分为4个阶段: 阶段Ⅰ, 1000~1250 A.D.(中世纪暖期), 温度达到千年来的峰值后下降, 主要受外部太阳辐射强迫与内部大气环流因素共同影响;阶段Ⅱ, 1250~1600 A.D.(小冰期前期), 区内温度下降幅度较大, 与火山活动剧烈期以及总太阳辐射(TSI)低值期重合, 加之内部大气环流因素共同影响, 大大加剧了降温效应;阶段Ⅲ, 1600~1900 A.D.(小冰期后期), TSI有所增强, 且东亚冬季风(EAWM)减弱、东亚夏季风(EASM)增强, 但产生的增温效应在一定程度上与火山活动外部强迫相互抵消, 故温度产生小幅度回升, 但未恢复到暖期水平;阶段Ⅳ, 1900~2000 A.D., (现代暖期), 气候系统从一系列火山喷发的影响中恢复, 进入了以人类活动产生的温室气体为主导因素的阶段。
The lower Yangtze River region is a typical area in China influenced by the East Asian monsoon.Existing studies on past climate changes have predominantly focused on the reconstruction of hydrological changes and their relationship with human activities.However,understanding temperature variations and their underlying mechanisms over the past millennium remains limited.This study utilized an 86 cm sediment core(30°20'N,117°00'E)from Shengjin Lake(30°15'~30°28'N,116°58'~117°14'E)in the lower Yangtze River region.Radiocarbon dating(14C)revealed that the core contains sedimentary records spanning the past millennium.The core was divided into 37 samples,which were analyzed for glycerol dialkyl glycerol tetraethers(GDGTs).Through regional comparison,the source of branched GDGTs(brGDGTs)in Shengjin Lake was identified,and a temperature calibration formula for brGDGTs specific to this lake was applied.The study reconstructed temperature changes in the Shengjin Lake basin over the past millennium and discussed the associated driving mechanisms.The results indicated that temperature changes in the Shengjin Lake area generally exhibited a fluctuating downward trend prior to the modern warm period,with the highest temperature recorded during the Medieval Warm Period,rather than the present warm period.Moreover,the reconstructed temperature trends from Shengjin Lake were consistent with broader regional patterns.Based on these temperature reconstructions,the study divided temperature changes in the region over the past millennium into four stages:StageⅠ(1000~1250 A.D.,Medieval Warm Period):The temperature peaked and then declined,primarily influenced by external solar radiation forcing and internal atmospheric circulation factors.StageⅡ(1250~1600 A.D.,Early Little Ice Age):A significant temperature drop occurred,coinciding with periods of intense volcanic activity and low total solar irradiance(TSI),which,together with internal atmospheric circulation factors,greatly intensified the cooling effect.StageⅢ(1600~1900 A.D.,Late Little Ice Age):TSI increased,the East Asian Winter Monsoon(EAWM)weakened,and the East Asian Summer Monsoon(EASM)strengthened.However,the warming effect was partially offset by external volcanic forcing,resulting in only a slight temperature rise,without returning to the levels of the warm periods.StageⅣ(1900~2000 A.D.,Modern Warm Period):The climate system recovered from the impacts of several volcanic eruptions and entered a phase dominated by greenhouse gas emissions from human activities.
作者
马再园
汪勇
韩瑞超
金院
李杨
吴立
苗雨青
徐仪红
徐文彬
强薇
MA Zaiyuan;WANG Yong;HAN Ruichao;JIN Yuan;LI Yang;WU Li;MIAO Yuqing;XU Yihong;XU Wenbin;QIANG Wei(School of Geography and Tourism,Anhui Normal University,Wuhu 241002,China;Anhui Key Laboratory of Earth Surface Processes and Regional Response in Yangtze-Huaihe Basin,Wuhu 241002,China;State Key Laboratory of Lake and Watershed Science for Water Security,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 211135,China;Buearu of Anhui Shengjin Lake National Nature Reserve,Chizhou 247230,China)
出处
《第四纪研究》
北大核心
2025年第3期776-788,共13页
Quaternary Sciences
基金
国家自然科学基金项目(批准号:41771228)
安徽师范大学校博士启动金项目(批准号:2017XJJ36)共同资助。
关键词
古温度重建
GDGTs
长江下游
湖泊沉积
升金湖
paleotemperature reconstruction
GDGTs
lower reaches of the Yangtze River
lake sediment
Lake Shengjin
