甘肃合水地区全新世以来土壤剖面黑碳记录及其气候变化  

Black carbon record of Loess-paleosol profile and climate change at Heshui site during Holocene

作　　者：廖冰[1] 谭志海[1] 孙斌[1] 龙艳侠 范汇晨 刘钊[1] 

机构地区：[1]西安工程大学环境与化学工程学院,西安710048

出　　处：《地球环境学报》2017年第1期15-24,共10页Journal of Earth Environment

基　　金：中科院地球环境研究所黄土与第四纪地质国家重点实验室开放基金(SKLLQG1202);中国科学院气溶胶化学与物理重点实验室开放基金~~

摘　　要：针对甘肃合水马家村(MJC)全新世黄土剖面进行野外采样,分析磁化率和黑碳(焦炭和烟炱)等古气候指标,试图探讨黄土高原北部全新世以来生物质燃烧特征以及自然生态环境演变过程,结果表明:末次冰期和全新世早期(11500—8500 a BP)气候寒冷而干旱,区域野火事件时而发生,植被生物量是此阶段野火发生与蔓延的限制因素;距今8000年以来,黑碳和炭屑浓度整体呈现下降趋势。由于季节性降水增多从而抑制大范围火灾发生几率。然而,8000—7000 a BP和3500—2500 a BP野火频率明显上升,这可能与仰韶时期老官台文化和寺洼文化时期的古人类放火烧荒和开垦农田等活动有关;全新世晚期(3100 a BP至今)气候进一步干旱,生物质燃烧增强与人口增加和人类土地利用水平密切相关,其中1500—1000 a BP出现一次较为明显的峰值,这可能与隋唐以来该区农耕活动加强有关。可见,近2000年以来黄土高原北部地区生物质燃烧特征受到气候和人类活动复合驱动所控制。Background, aim, and scope The study site is located in the climate-sensitive regions of the semi-arid and subhumid Asian monsoon belt, which is in the southwestern part of the ecotone between Chinese traditional dry farming and nomadic pastoral practice. The region has also experienced a long and complex regional land- use history, in which slash-and-burn cultivation by means of ignited fire and deforestation for dry farming has been traced back to at least 8000 year. Meanwhile, many of the Neolithic cultures that practiced dry farming by means of ignited fire arose on the loess plateau since the Holocene, such as the Laoguantai Culture （8000-- 7000 a BP） and the Siwa Culture （14C cal 3350--2650 a BP）. In this research, the Holocene loess-paleosol profiles were selected for its proximity to archaeological sites in the region. An interdisciplinary approach has been adopted to study wildfire history and its interactions with changes in monsoonal climate and human activities on the loess tableland during the Holocene. Materials and methods A high-resolution sedimentary charcoal and black carbon （char and soot） records from the loesssoil profile in the middle of loess plateau, combined with Magnetic susceptibility, Total organic carbon （TOC） analyses, pollen counts and other paleoclimatic- proxies reveal past wildfire history and the evolution of natural ecological landscape. Results Black carbon （BC） preserved in accretionary loessesoil profiles recorded changes in fire, which may be due to climatic variations, changes in vegetation, and human activities. EC-soot contents showed a stable rising trend since 12000 years, although a marked decline occurred in the past 100 years. EC-char contents ranges from 0.031 rag. g-I to 0.179 mg-g-1; EC-soot contents ranges from 0.072 mg.g-1 to 0.149 mg.g 1 since 12000 years BR More specifically, EC-char values increased gradually from the early Holocene to relatively high during 8000--7000 a BP and 3500--2500 a BP and then gradually decrease. In the MJC profi

关 键 词：野火 气候变化 全新世 黑碳 炭屑 

分 类 号：S151.9[农业科学—土壤学] P532[农业科学—农业基础科学]