北极东西伯利亚陆架黑碳的地球化学特征及其环境意义

Geochemical characteristics of black carbon in surface sediments of the East Siberian Arctic Shelf and their environmental implications

  • 摘要: 热成因黑碳与气候变化和人类活动关系密切。在全球变暖背景下,这类碳的排放、从陆向海的转移及其环境归宿对于理解北极快速变化下陆源有机碳的源汇过程及其气候环境效应具有重要的科学意义。北极东西伯利亚陆架是全球最为宽浅的陆架,接收了大量来自径流和海岸侵蚀输入的陆源物质,尤其近年来环北极野火的频繁发生,因而成为研究北极沉积黑碳源−汇过程的理想区域。本研究对东西伯利亚陆架表层沉积物中黑碳的含量和组成、空间分布特征及其影响因素等进行了研究,结果表明,黑碳的含量为0.1~2.3 mg/g,平均为0.99 mg/g,其中来自生物质燃烧贡献为主的焦炭平均占70%以上。黑碳总体空间分布具有显著的异质性,拉普捷夫海和东西伯利亚海西部地区黑碳含量较高,与海岸侵蚀和河流输入关系密切;陆架东部(包括楚科奇海)陆源输入相对较少,黑碳含量相对较低。不同类型黑碳的空间分布格局显著不同;对于近岸区,来自径流和海岸侵蚀的输入可能是焦炭从陆向海的主要输入方式。

     

    Abstract: Pyrogenic black carbon (BC) is closely related to climate change and human activities. In the context of global warming, the BC emission and transfer from land to sea and the environmental fate provide important scientific clues for understanding the source-sink course of terrigenous organic carbon and its climate and environmental effects under rapid climate change in the Arctic area. The East Siberian Arctic Shelf is the widest and shallowest shelf in the world, receiving a large amount of terrestrial material input from runoff and coastal erosion. Especially in recent years, frequent occurrence of wildfires around the Arctic makes it an ideal area for studying the course and route of source-sink of BC deposited in the Arctic waters. Based on the data of samples collected from the East Siberian shelf, the content, composition, spatial distribution, and influencing factors of BC in surface sediments were studied. Preliminary results show that the content of BC is 0.1~2.3 mg/g, on average of 0.99 mg/g. Among them, char from biomass combustion contributed more than 70% on average. The spatial distribution of BC is very heterogeneous. BC in the Laptev Sea and the western part of the East Siberian Sea is high, which is closely related to coastal erosion and river input. The eastern part of the shelf (including the Chukchi Sea) has less terrigenous input and relatively low BC content. The spatial variability of different types of BC is obvious. In the nearshore region, runoff and coastal erosion is probably the main input pathway of char.

     

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