楚科奇海百年尺度冻土有机碳的埋藏及其对气候变化的响应

The burial of permafrost organic carbon in the Chukchi Sea and its response to climate change in the past 200 years

在全球变暖的背景下,北极出现了冻土退化、夏季海冰减少、陆地径流输入增加和沿岸侵蚀加剧等一系列变化。随着全球变暖,封存于冻土中的有机碳(Organic Carbon,OC)正在向海加速迁移和释放,这将影响北冰洋的碳循环的格局,但目前鲜有证据能直接证实这一推论。本文通过分析楚科奇海两根百年尺度沉积岩芯的木质素和碳同位素,讨论了其所埋藏的有机质的来源和剖面变化情况。结果显示楚科奇海柱状沉积物中的有机碳来源于陆生C3植物的草本组织和海洋源生产的混合贡献;沉积物中木质素的绝对含量Σ8呈现上升趋势,证明随着全球变暖,更多的陆源物质被输运到楚科奇海。本研究表明人类活动引起的全球变暖确实增加了冻土有机碳向海的迁移,陆源输入增强导致的木质素含量增加是百年尺度下全球变暖导致冻土融化增强的直接证据。

Against the backdrop of global warming,the Arctic has experienced a series of changes,including perma-frost degradation,reduced summer sea ice,increased land runoff,and intensified coastal erosion.With global warm-ing,organic carbon(OC)stored in permafrost is accelerating its migration and release to the sea,which will affect the pattern of carbon cycling in the Arctic Ocean.However,there is currently little evidence to directly confirm this inference.This article analyzes the lignin and carbon isotopes of two hundred year scale sedimentary cores in the Chukchi Sea,and discusses the sources and profile changes of the buried organic matter.The results showed that the organic carbon in the columnar sediments of the Chukchi Sea came from a mixed contribution of herbaceous tis-sue of terrestrial C3 plants and marine source production.The absolute content of ligninΣ8 in sediment shows an overall upward trend,indicating that with global warming,more terrestrial materials are being transported to the Chukchi Sea.This study indicates that global warming caused by human activities has indeed increased the migra-tion of organic carbon from permafrost to the sea,and the increase in lignin content due to enhanced terrestrial in-puts is direct evidence of the enhanced melting of permafrost caused by global warming on a century scale.