大火历史及其与古气候关系研究

火广泛地存在于自然界和人类社会中,并在现代生态系统的形成过程中扮演了重要角色。沉积物中的元素碳记录了大火发生的历史,对之进行定量分析可得到大火频率的长期记录,分析方法包括显微镜观察和化学氧化处理。化学方法通常是用HCl-HF酸溶解碳酸盐及硅酸盐,再通过氧化反应去除有机物。几种沉积相中大火历史研究实例表明,大火改变了植被格局,进而影响区域气候;燃烧排放的气体和颗粒对大气化学性质也产生重大影响。

FIRE HISTORY AND ITS IMPACT ON PALEOCLIMATE CHANGE

Fire is widespread in nature. It played a central role in moulding many modern ecosystems. Fire history can be reconstructed from such record as element carbon preserved in sediments, which can be quantified by microscope and chemical oxidation. Chemical techniques for the isolation of element carbon generally involve the dissolution of carbonates and silicates by HCl HF acid attack, followed by oxidation of contaminating organic matter to leave a residue composed of element carbon. Several studies of fire history in lake, ice core and marine sediments suggest that fire has exerted influences on vegetation patterns as well as regional climate, and the resulting gaseous and particulate emissions have affected the atmospheric chemistry.