img

官方微信

高级检索

中国沙漠 ›› 2015, Vol. 35 ›› Issue (5): 1156-1162.DOI: 10.7522/j.issn.1000-694X.2014.00218

• 古气候与环境演变 • 上一篇    下一篇

全新世中期毛乌素沙地炭屑记录与火灾历史

蔡晓敏1,2, 苗运法1, 靳鹤龄1, 刘冰1, 严永耀1,2   

  1. 1. 中国科学院寒区旱区环境与工程研究所 中国科学院沙漠与沙漠化重点实验室, 甘肃 兰州 730000;
    2. 中国科学院大学, 北京 100049
  • 收稿日期:2014-11-07 修回日期:2014-12-29 出版日期:2015-09-20 发布日期:2015-09-20
  • 通讯作者: 苗运法(Email: miaoyunfa@lzb.ac.cn)
  • 作者简介:蔡晓敏(1990-),女,江西吉安人,硕士研究生,主要研究方向为古气候环境记录和全球变化。Email: xiaomincai11@sina.com
  • 基金资助:

    中国科学院重点部署项目(KZZD-EW-04-04);国家自然科学基金项目(41271215,41172153);中国科学院盐湖资源与化学重点实验室开放基金项目(KLSLRC-KF-13-DX-1);中国科学院寒区旱区环境与工程研究所青-人才基金项目(51Y451211);中国科学院沙漠与沙漠化重点实验室开放基金项目(KLDD-2014-011)

Mid-Holocene Charcoal Records and Fire History in the East Edge of the Mu Us Sandy Land, China

Cai Xiaomin1,2, Miao Yunfa1, Jin Heling1, Liu Bing1, Yan Yongyao1,2   

  1. 1. Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2014-11-07 Revised:2014-12-29 Online:2015-09-20 Published:2015-09-20

摘要:

炭屑是探索自然火和人类用火及其驱动机制的重要指标。作者试图通过孢粉提取法获得毛乌素沙地东缘锦界剖面全新世中期(7.5~4.6 ka)的炭屑记录, 用来揭示该地区炭屑变化特征和火灾历史, 并探讨其与气候环境变化之间的关系。结果表明:在7.5~4.6 ka期间炭屑浓度变化范围为340~17 420粒·g-1, 平均为3 350粒·g-1。剖面炭屑总浓度变化趋势曲线呈“弓形”, 即在7.2 ka以前炭屑浓度较低, 平均约为1840粒·g-1 ;在7.2~6.6 ka浓度最高, 平均约为5 280粒·g-1, 并在6.8 ka前后达到峰值17 400粒·g-1 ;在6.6 ka之后浓度下降, 平均为1720粒·g-1。同时, 炭屑粒径指标表明<50 μm的炭屑占主导,>100 μm的炭屑稀少。炭屑浓度主要反映火灾频率和强度, 炭屑粒径则反映火灾距离和范围, 即毛乌素沙地东部在全新世中期火灾活动相对频繁并在6.8 ka左右达到最大值, 同时炭屑物源较远, 主要为区域性火灾。锦界剖面的化学风化指数、地球化学元素和粒度变化特征表明该地区在7.5~4.6 ka气候条件整体较好, 湿度增加, 处于全新世适宜期, 并在7.2~6.6 ka达到最佳值, 这表明毛乌素沙地的火灾主要发生在气候最佳时期。结合毛乌素沙地及其邻区的孢粉资料推测, 该地区在全新世气候适宜期时植被相对茂盛, 为毛乌素沙地的火灾提供了丰富的可燃烧物, 可能是火灾增多的主要原因。

关键词: 毛乌素沙地, 炭屑, 火灾, 全新世, 驱动机制

Abstract:

Charcoal is an important proxy to explore wildfire and human use of fire and its driving forces. The author tried to collect the mid-Holocene(7.5-4.6 ka) charcoal records by pollen extract method at Jinjie profile to reveal the charcoal concentrations and fire history in the east edge of the Mu Us Sandy Land, then explore its relationships with paleoclimate and paleoenvironment changes. The results showed that during 7.5-4.6 ka, the charcoal concentrations range between 340 and 17 42 grains·g-1, with an average of 3 350 grains·g-1. The curve of charcoal concentrations expressed a shape of 'bow', characterized by relatively low values before 7.2 ka, with an average of 1 840 grains·g-1; high values during 7.2-6.6 ka, with an average 5 280 grains·g-1; the peak occurred at 6.8 ka, attained 17 400 grains·g-1; After 6.6 ka, the concentration decreased, with an average of 1 720 grains·g-1. Meanwhile, the charcoal grain-size showed that the part of <50 μm dominated the whole profile. The charcoal concentrations mainly reflect the fire frequencies and intensities, while the charcoal grain-size reflects the fire distances and ranges. So, at the JJ profile, the fire activity was relatively frequent and reached the maximum in 7.2-6.6 ka in the east edge of the Mu Us Sandy Land, and the fire source was from a relatively farther distance. At the same time, the variations of the chemical weathering index, geochemical elements, and grain-size of the sedimentary materials at the JJ profile indicated an optimal climate between 7.2 and 6.6 ka, characterized by the relatively most humid condition. The strongest wildfire in the Mu Us Sandy Land occurred in the relatively better environment. Combining with the pollen data in the Mu Us Sandy Land and the surrounding areas to the southeast(e.g., Loess Plateau) showed that the relatively exuberant vegetation during the Holocene climatic optimum may have provided enough biomass for the fire.

Key words: Mu Us Sandy Land, charcoal, fire, Holocene, driving mechanism

中图分类号: