天山东部冰川雪坑离子浓度特征的对比研究--以奎屯河哈希勒根51号冰川和哈密庙尔沟平顶冰川为例

Ion Concentration in Snow Pits on Glaciers in Eastern Tianshan Mountain——Take Haxilegen Glacier No.51 of Kuitun River and Hami Miaoergou Flat-Topped Glacier As an Example

对2004年获取的天山奎屯河哈希勒根51号冰川1个雪坑和哈密庙尔沟平顶冰川4个雪坑的离子浓度特征进行了研究,结果表明:Ca2+、NO3-和SO24-是哈密庙尔沟平顶冰川雪坑雪层和积累区雪坑底部冰中的主要离子(尤其是Ca2+),其雪层中的主要阳离子关系可在底部冰中得以较好的反映,但雪层中各离子浓度与海拔的相关性不明显,可能与海拔的跨度较小和挖取的雪坑较疏有关;雪坑底部冰中的离子浓度与海拔间明显的相关性说明淋融作用随着海拔升高、气温降低而逐渐减弱。SO24-和Ca2+是奎屯河哈希勒根51号冰川雪坑中的主要离子(尤其是SO42-),其雪坑离子化学特征与哈密庙尔沟平顶冰川差别较大,可能与哈密庙尔沟平顶冰川处于塔克拉玛干沙漠、古尔班通古特沙漠和鄯善沙漠的下风向相关,还可能与雪层内淋融作用的强弱和沉积通量的高程效应有关。哈密庙尔沟平顶冰川积累区雪坑中NH4+、NO3-和K+的Cs/Ci较Ca2+、Mg2+和Na+要大,奎屯河哈希勒根51号冰川Na+和NH4+的"雪冰比"较Cl-、SO42-、Mg2+和Ca2+要大,说明这两条冰川雪坑中的Ca2+和Mg2+信号较其它离子可能更易于在冰芯记录中保存下来,为冰芯研究和古气候记录的恢复提供了保障。

The ion concentrations were studied in both four snow pits on Hami Miaoergou Flat-Topped Glacier and one snow pit on Haxilegen Glacier No. 51 of Kuitun river in eastern Tianshan Mountain, and both snow pits were retrieved in 2004. The results show that the Ca^2＋ , NO3- and SO4^2-, particularly Ca^2＋ , are major ions in the snow of snow pits in both ablation and accumulation area and also in the ice of snow pits in accumulation area on Hami Miaoergou Flat-Topped Glacier, where the relationships among major cation concentrations in snow of snow pits can be revealed by ion concentrations in the ice of snow pits, but the correlation between ion concentrations in the snow of snow pits and elevation is not obvious, which probably can be attributed to the narrow span of elevation and sparse snow pits on glacier. However, the good correlation between ion concentrations in the ice of snow pits and elevation indicates that the elution process weakened gradually with the elevation rise and temperature decrease. The SO^2- and Ca^2＋ , particularly SO^2- , are major ions in snow and ice of snow pits on Haxilegen Glacier No. 51 of Kuitun river, where its ion chemistry in snow pits is different from that on Hami Miaoergou Flat-Topped Glacier, which is most likely related to the geographical location of Hami Miaoergou Flat-Topped Glacier that is located in the leeward site of the Taklimakan desert, Shanshan desert and Gurbantunggut desert, and also probably associated with the elution process in snow pits and altitude effect of deposition flux. The ratios （Cs/Ci） of NH4＋ , NO3- and K ~ is bigger than that of Ca^2＋ , Mg^2＋ and Na ^＋ of snow pits in accumulation area on Hami Miaoergou Flat- Topped Glacier, and also the ratios of Na^＋ and NH4＋ is bigger than that of Cl^- , SO4^2- , Mg^2＋ and Ca^2＋ of snow pits on Haxilegen Glacier No. 51 of Kuitun river, which indicate that the signals of Ca^2＋ and Mg^2＋ in snow pits both on Hami Miaoergou Fiat-Topped Glacier and Haxilegen Glacier No. 51 of Kuitun river may be easier to be preserved in ice cores than other ions in snow pits. This guaranteed studies of ice core and reconstrution of paleoclimate records on these two glaciers.