格陵兰NEEM冰芯1711~1969年火山事件重建

THE HISTORY OF EXPLOSIVR VOLCANISM IN A GREENLAND NEEM ICE CORE DURING 1711~1969

冰芯作为良好的地质载体,为第四纪气候和环境研究提供了详实的信息。本研究利用连续流动装置对格陵兰冰盖西北部获取的一支90 m浅冰芯(命名为NEEM2009S1:77.45°N,51.06°W;海拔高度2450 m)融化处理,对氧和氢同位素比率(δ^(18)O和δD,2 cm分辨率)和硫酸根离子浓度(SO_(4)^(2-),10~12 cm分辨率)进行了测试。基于δ^(18)O和关键的强火山事件对该冰芯进行了定年,结果为1711~1969年(不确定性为±1年);通过非海盐硫酸根离子浓度(nss SO_(4)^(2-))重建了该冰芯过去1711~1969年期间火山事件的历史。SO_(4)^(2-)浓度和通量很好地揭示了不同强度大小的火山事件。评估了强火山事件(VEI≥5)其产生的气候制冷效应;同时,由于该冰芯距离冰岛较近,本研究重点讨论了该冰芯对冰岛火山事件的记录历史,数据结果对了解冰岛历史时期火山信息具有重要的意义;此外,低纬度东亚与阿拉斯加地区的火山也容易传输至格陵兰冰盖。重建结果对于更好的理解火山事件对区域、全球环境与气候的影响具有重要的参考价值。

In this study,as part of the NEEM deep ice core,a 90 m shallow ice core(North Eemian(NEEM)2009 S1:77.45°N,51.06°W;2450 m a.s.l.)was drilled from northwest Greenland.Ice core samples from this core were melted using continuous flow analysis.The chemical compositions(with resolutions of 2.5 cm and 5 cm)and ratios ofδ^(18)O andδD(with resolutions of 10~12 cm)were analysed using the ion chromatography and Picarro wavelengthscanned cavity ring-down spectrometers,respectively.The results indicate that the ages in the ice core range from 1711 to 1969(19 m to 90 m)usingδ^(18)O annual layer information and volcanic markers(i.e.,non-sea salt(nss)sulfate).The estimated dating uncertainty is about±1 a at the bottom of the core.A detailed history of volcanism covering the last 259 a was reconstructed.The measured non-sea salt sulfate concentrations agree well with documented volcanic events,which indicates that the history of volcanic eruptions in Iceland is clearly preserved in this shallow core.The eruption data recorded in the NEEM2009S1 core demonstrate that the larger volcanic events have a significant cooling effect,and volcanic aerosols from East Asia are easily transported to the Greenland ice sheet,which will contribute to a better understanding of the processes controlling the climate and environment of Greenland.