孙伟伟,
沈吉
中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 江苏 南京 210008

基金项目: 国家自然科学基金项目（批准号：41430530和41702183）资助


详细信息

作者简介: 孙伟伟, 男, 29岁, 助理研究员, 自然地理学专业, E-mail:wwsun@niglas.ac.cn

中图分类号: P942;P532

收稿日期:2019-07-23
修回日期:2019-10-31
刊出日期:2020-01-30

A black carbon record from Lake Xingkai in Northeast China and implication for environmental reconstruction since the last interglacial period

Sun Weiwei,
Shen Ji
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, Jiangsu



MSC: P942;P532

--> Received Date: 23 July 2019
Revised Date: 31 October 2019
Publish Date: 30 January 2020


摘要
摘要:在我国东北地区，黑碳记录较少，尤其是长时间尺度记录，区域火灾如何响应于气候变化还存在争议。本研究通过对兴凯湖XK08-A2钻孔约336 cm岩芯，共136个沉积物样品的黑碳含量进行了分析，并结合石英光释光和加速器质谱¹⁴C测年结果，探讨了末次间冰期以来东北地区火灾历史与古环境的联系。兴凯湖沉积物黑碳含量的平均值在末次间冰期、末次冰期以及全新世分别为0.51±0.10 ‰、0.68±0.15 ‰和0.71±0.20 ‰。兴凯湖沉积物中黑碳含量从下向上呈增加趋势，表明末次间冰期区域火灾的发生频次较低、规模较小，末次冰期火灾的频次升高、规模越来越大，全新世阶段火灾的频次和规模与末次冰期相当。这些变化与轨道尺度东亚夏季风进退以及人类活动密切相关。从末次间冰期到末次冰期，东亚夏季风变化是东北地区火灾发生的主要控制因素。强盛的东亚夏季风带来充沛的降水，促进了低洼地区湿地沼泽的发育，缩短了火风险期，致使发生大规模火灾的概率较低。自然背景下季风降水主导我国东北地区火灾的发生，与黄土高原和西南地区一致，但与欧美地区受温度影响存在显著的空间差异。全新世在人类活动的影响下，虽然东亚夏季风增强，但是区域大规模火灾发生的概率已达到末次冰期的水平。
关键词: 黑碳/
火灾/
东亚夏季风/
气候变化/
人类活动/
湖泊沉积

Abstract:Black carbon (BC) is pervasive in the environment but playing an important role in the global carbon cycling and paleoenvironmental reconstructions. There is few long-term BC record from Northeast China and the relationship between fire regime and climate is not well understood from this region, which hampers prediction of the response of fire to future climate change. In this study, we present a BC record from Lake Xingkai since the last interglacial period, in order to determine the main factor influencing regional fire regime.
Two parallel and overlapping sediment cores XK08-A1 (308 cm in depth) and XK08-A2 (336 cm in depth) were collected near the China-Russia border (45°12'21.7"N, 132°30'33.3"E) using a UWITEC piston corer in the summer of 2008. In the laboratory, core correlation between XK08-A1 and XK08-A2 was carried out using surface scanning magnetic susceptibility. Core XK08-A1 was used for optically stimulated luminescence (OSL) dating, and a total of 49 OSL samples were obtained. The chronology of XK08-A2 is established mainly based on the correlation of the magnetic susceptibility with Core XK08-A1, where the depth of 336~216 cm is corresponded to the Marine Isotope Stage (MIS) 5 216~27 cm to the MIS 4~2, and 27~0 cm to the MIS 1.
Samples at 1-cm intervals above 70 cm depth and 4-cm intervals below were used for the analysis of BC content, respectively, yielding a total of 136 samples. The BC in the freeze-dried bulk samples were extracted using the dichromate (K₂Cr₂O₇) oxidation method. BC measurements were performed using a Flash EA 1112 elemental analyzer. The BC content is relatively low during the last interglacial period with a mean of 0.51±0.10 ‰; and relatively higher during the last glacial period with a mean of 0.68±0.15 ‰; it is slightly higher during the Holocene with a mean of 0.71±0.20 ‰. The results indicate that the scale of regional fires in the last interglacial period was relatively small, compared to the scale of fires in the last glacial period. Meanwhile, the scale of fires in the Holocene could exceed that in the last glacial period.
These changes are closely related to the intensity of the East Asian summer monsoon and human activities. From the last interglacial period to the last glacial period, the intensity of East Asian summer monsoon is the main controlling factor of fire occurrence in Northeast China. The strengthened East Asian summer monsoon brought abundant rainfall, promoting the development of wetlands and marshes in low-lying areas, and resulting in a low probability of large-scale fires. The orbital time-scale fire regime in Northeast China is similar to that of the Chinese Loess Plateau and Southwest China under the natural background. However, there are significant spatial differences between monsoonal China and the continents of Europe and North America, where fire regime is more sensitive to temperature changes. The fire regime in Northeast China may have been influenced by human activity in the Early Holocene, and possibly related to the intensification of cereal cultivation in the Late Holocene.
Key words:black carbon/
fire/
East Asian summer monsoon/
climate change/
human activity/
lacustrine sediment



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