1954年以来珠穆朗玛峰地区两支冰芯记录的对比分析

根据珠穆朗玛峰(以下简称珠峰)地区远东绒布冰川和东绒布冰川两支冰芯记录的恢复,1954年以来的冰川净积累量相差达1倍以上,但两支冰芯记录均表明:20世纪60年代冰川净积累量出现急剧减少现象,印度季风系统的突变可能是造成冰川净积累量变化的主要原因.两支冰芯δ¹⁸O剖面的总体变化趋势基本相同,但研究时段内远东绒布冰芯的δ¹⁸O平均值比东绒布冰芯的相应值低3.12‰,其原因有待进一步研究.两支冰芯的主要离子浓度剖面之间也存在较明显的差异,沉积后过程是导致这一差异的原因所在.

Comparison of Two Ice Core Records Since 1954 from Mt. Qomolangma (Everest) Region

A 41-mice core was recovered from the Far East Rongbuk Glacier(FER), and another 80.4-m core from the East Rongbuk Glacier(ER), Mount Qomolangma(Everest)region. Both of the cores are dated by the reference layers of β activity peaks correlated to known nuclear fallout events and the seasonal variations of the δ¹⁸O and the major ions. The two cores have roughly the same trends in δ¹⁸O and net-accumulation since 1954, which indicate the same climate controlling in this region. Although the average net-accumulation rate at the FER core site is less than half of the corresponding value at the ER core site owing to the difference in location and melting condition, both of the net-accumulation records of the ER core and the FER core show clearly a sharp decline from the middle 1950s to the late 1960s, which might reflect the sudden climate change in the Asian monsoon region during that period. It is likely that the increase in atmospheric sulphate aerosol has already begun to affect the monsoon in the Himalayas, offsetting the increasing trend in monsoon precipitation that would have been caused by the increase in atmospheric greenhouse-gases. Though similar smoothing trend is apparent for the δ¹⁸O profiles of the two cores, the mean δ¹⁸O of the FER core is 3.12 less than that of the ER core for the period 1954～1996. This phenomenon needs much more study. Moreover, much difference exists for the mayor ionic profiles and their corresponding cumulative fluxes of the two cores. core. Since the two ice cores drilling sites are only several kilometers apart and at the same altitude, the apparent difference between the chemical records of the two cores should be attributed to the post-depositional modification.