沉积物中黑碳在古环境古气候研究中的应用

Application of black carbon in sediments in paleoenvironment and paleoclimate studies

  • 摘要: 黑碳是指生物质或化石燃料不完全燃烧以及岩石风化所产生的一系列含碳物质连续体的统称。其特殊的物理化学性质可对全球气候环境造成显著影响,如加剧温室效应、影响水文循环和碳封存;由于其具有较为稳定的化学性质以及燃烧前后碳同位素分馏小的特征,又使黑碳作为一种载体被应用到地质时间尺度火历史与植被演化重建工作中。通过对黑碳的特征、来源、循环、在沉积物中的提取方法及其在不同时间尺度古环境重建中的应用进行评述,提出了目前黑碳记录在古环境重建中存在的一些问题,如黑碳的降解转化过程对黑碳沉积的影响,以及黑碳年龄具有滞后性,沉积物中黑碳来源及沉积过程的复杂性,地质时间尺度黑碳参与碳循环的角色仍不明确等。另外对未来研究进行了展望:相对于陆地土壤、湖泊、河流、冰川等载体,海洋沉积物中黑碳的研究工作还非常缺乏。自1966年以来,深海钻探计划、国际大洋钻探计划、综合大洋钻探/发现计划航次及我国自主航次在全球海洋获取了大量高质量沉积岩芯,为未来利用黑碳研究新生代以来构造、气候、植被、火乃至人类活动之间的相互作用提供了可能性。

     

    Abstract: Black carbon refers to a series of continuum of carbonaceous substances from incomplete combustion of biomass or fossil fuels or weathering of rocks. Its unique physical and chemical properties have significant impacts on the global climate and environment, such as exacerbating the greenhouse effect, affecting hydrological cycling and carbon sequestration. Due to its relatively stable chemical properties and small carbon isotope fractionation before and after combustion, black carbon has been used as a reliable proxy for the reconstruction of geological time-scale fire history and vegetation evolution. We reviewed the characteristics, sources, cycles, extraction methods in sediments, and their applications in paleoenvironmental reconstruction on different time scales of black carbon, and raised some issues in the current application of black carbon records for paleoenvironmental reconstruction. For example, the impact of the degradation and transformation of black carbon on black carbon deposition, as well as the lag in black carbon age, the complexity in black carbon origination and deposition, and the role of black carbon in carbon cycling at geological time scales, are still unclear. In addition, prospects for future research are presented: Unlike terrestrial soil, lakes, rivers, glaciers, and other carriers, black carbon in marine sediments are poorly studied. For more than half a century, international and national ocean drilling expeditions have obtained a large number of high-quality sedimentary cores in the global oceans, providing a possibility of using black carbon to study the interaction among tectonics, climate, vegetation, fire, and even human activities since the Cenozoic.

     

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