Variations in mineralogy of dust in an ice core obtained from northwestern Greenland over the past 100 years
Variations in mineralogy of dust in an ice core obtained from northwestern Greenland over the past 100 years
复制标题
DOI：
10.5194/cp-17-1341-2021
复制
发表时间：
2021-06
影响因子：
4.3
通讯作者：
Naoko Nagatsuka;K. Goto‐Azuma;Akane Tsushima;K. Fujita;S. Matoba;Y. Onuma;R. Dallmayr;Moe Kadota;M. Hirabayashi;Junzo Ogata;Yoshimi Ogawa‐Tsukagawa;Kyotaro Kitamura;M. Minowa;Yuki Komuro;H. Motoyama;T. Aoki
中科院分区：
文献类型：
--
作者：
Naoko Nagatsuka;K. Goto‐Azuma;Akane Tsushima;K. Fujita;S. Matoba;Y. Onuma;R. Dallmayr;Moe Kadota;M. Hirabayashi;Junzo Ogata;Yoshimi Ogawa‐Tsukagawa;Kyotaro Kitamura;M. Minowa;Yuki Komuro;H. Motoyama;T. Aoki
抽象的。我们的研究首次展示了过去100年格陵兰冰芯中矿物成分的高时间分辨率记录。为了重建格陵兰西北部矿物粉尘来源和输送过程的过去变化，我们利用扫描电子显微镜(SEM)和能量色散X射线光谱(EDS)分析了1915年至2013年Sigma-D冰芯中粉尘的形态和矿物组成。结果表明，冰芯矿物主要由硅酸盐矿物组成，其组成在数十年和年代际尺度上差异很大，表明近百年来不同时期的冰芯矿物来自不同的地质来源。不同矿物类型的年代际变化趋势不同。高岭石一般形成在温暖潮湿的气候带，在较冷的时期(1950-2004年)丰富，而在干旱、高纬度和局部地区形成的云母、绿泥石、长石、镁铁质矿物和石英在较温暖的时期(1915-1949和2005-2013年)丰富。与格陵兰地表温度记录的比较表明，这些矿物的相对丰度的几十年变化可能受到格陵兰当地温度变化的影响。轨迹分析表明，在两个增暖期，矿物主要来自格陵兰西海岸，这可能是由于最近变暖导致的融化季节格陵兰沿海地区冰雪覆盖时间缩短，导致来自当地无冰区的粉尘增加。与此同时，加拿大北部的古代沉积物形成于过去较温暖的气候中，似乎是较冷时期(1950-2004年)的最佳候选者。我们的结果表明，扫描电子显微镜-能谱分析可以探测到近几年低沙尘浓度期间冰芯沙尘源的变化。
Abstract. Our study is the first to demonstrate a high-temporal-resolution record of mineral composition in a Greenland ice core over the past 100 years. To reconstruct past variations in the sources and transportation processes of mineral dust in northwestern Greenland, we analysed the morphology and mineralogical composition of dust in the SIGMA-D ice core from 1915 to 2013 using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results revealed that the ice core dust consisted mainly of silicate minerals and that the composition varied substantially on multi-decadal and inter-decadal scales, suggesting that the ice core minerals originated from different geological sources in different periods during the past 100 years. The multi-decadal variation trend differed among mineral types. Kaolinite, which generally formed in warm and humid climatic zones, was abundant in colder periods (1950–2004), whereas mica, chlorite, feldspars, mafic minerals, and quartz, which formed in arid, high-latitude, and local areas, were abundant in warmer periods (1915–1949 and 2005–2013). Comparison to Greenland surface temperature records indicates that multi-decadal variation in the relative abundance of these minerals was likely affected by local temperature changes in Greenland. Trajectory analysis shows that the minerals were transported mainly from the western coast of Greenland in the two warming periods, which was likely due to an increase in dust sourced from local ice-free areas as a result of shorter snow/ice cover duration in the Greenland coastal region during the melt season caused by recent warming. Meanwhile, ancient deposits in northern Canada, which were formed in past warmer climates, seem to be the best candidate during the colder period (1950–2004). Our results suggest that SEM–EDS analysis can detect variations in ice core dust sources during recent periods of low dust concentration.