过去5000 a以来抚仙湖沉积物有机质碳同位素的古环境指示意义

发布时间：2019-01-13 20:40

【摘要】：通过测定抚仙湖沉积物全有机样品的稳定碳同位素组成(δ~(13)C_(org))、总氮、总有机碳含量指标并计算碳氮比值,对过去5000 a以来抚仙湖沉积物有机质来源、δ~(13)C_(org)的影响因素及其所指示的古环境意义进行分析.结果表明:在过去的5000 cal a BP里,抚仙湖沉积物有机质主要来源发生明显变化,沉积物有机质输入由内源水生生物和陆生C_3植物共同输入(5000-2300 cal a BP阶段)转变为以内源沉水植物、浮游植物和藻类等输入为主(2000 cal a BP至今阶段);有机质来源发生变化是造成抚仙湖沉积物δ~(13)C_(org)值变化的主要原因;2000 cal a BP以来,陆源有机质输入的锐减与人类活动的影响密切相关;在2300-2000 cal a BP阶段,抚仙湖沉积物δ~(13)C_(org)值的快速变化可能指示了抚仙湖流域的古环境在这一时期经历了快速变化的气候事件.
[Abstract]:The source of organic matter in Fuxian Lake sediments since the past 5000 years was studied by measuring the stable carbon isotopic composition (未 ~ (13) C _ (org), total nitrogen and total organic carbon content index and calculating the ratio of carbon to nitrogen) of the total organic samples of Fuxian Lake sediment. The influencing factors of 未 ~ (13) C _ (org) and their paleoenvironmental significance were analyzed. The results show that in the past 5000 cal a BP, the main source of organic matter in Fuxian Lake sediment has changed obviously. The organic matter input of sediment changed from endogenous aquatic organisms and terrestrial C _ 3 plants (5000-2300 cal a BP) to endophyte, phytoplankton and algae (2000 cal a BP to now). The change of organic matter source is the main reason for the change of 未 ~ (13) C _ (org) value in the sediments of Fuxian Lake, and the sharp decrease of terrestrial organic matter input is closely related to the influence of human activities since 2000 cal a BP. During the period of 2300-2000 cal a BP, the rapid change of 未 ~ (13) C _ (org) in the sediment of Fuxian Lake may indicate that the paleoenvironment of Fuxian Lake basin experienced a rapidly changing climatic event in this period.
【作者单位】：云南师范大学旅游与地理科学学院;云南师范大学高原湖泊生态与全球变化重点实验室;
【基金】：国家自然科学基金项目(41201203) 云南省高端人才引进项目(2010CI111) 湖泊沉积与环境变化云南省创新团队项目(2010CI)联合资助
【分类号】：P532;P597

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