Isotopic and chemical analyses of a temperate firn core from a rnChinese alpine glacier and its regional climatic significance

摘要

Mt. Yulong is the southernmost currently glacier-covered area in Eurasia,rnincluding China. There are 19 sub-tropical temperate glaciers on the mountain,rncontrolled by the south-western monsoon climate. In the summer of 1999, a firn core,rn10. 10 m long, extending down to glacier ice, was recovered in the accumulation area of rnthe largest glacier, Baishui No. 1. Periodic variations of climatic signals above 7. 8 m rndepth were apparent, and net accumulation of four years was identified by the annual rnoscillations of isotopic and ionic composition. The boundaries of annual accumulation rnwere confirmed by higher values of electrical conductivity and pH, and by dirty rnrefreezing ice layers at the levels of summer surfaces. Calculated mean annual net rnaccumulation from 1994/1995 to 1997/1998 was about 900 mm water equivalent. The rnamplitude of isotopic variations in the profile decreased with increasing depth, and rnisotopic homogenization occurred below 7. 8 m as a result of meltwater percolation.rnVariations of δ18O above 7. 8 m showed an approximate correlation with the winter rnclimatic trend at Li Jiang Station, 25 km away. Concentrations of Ca2+ and Mg2+ were rnmuch higher than those of Na+ and K+ , indicating that the air masses for precipitation rnwere mainly from a continental source, and that the core material accumulated during rnthe winter period. The close correspondence of C1- and Na+ indicated their common rnorigin. Very low concentrations of SO2-4 and NO3- suggest that pollution caused by rnhuman activities is quite low in the area. The mean annual net accumulation in the core rnand the estimated ablation indicate that the average annual precipitation above the rnglacier's equilibrium line is 2400 - 3150 mm, but this needs to be confirmed by longrnterm observation of mass balance.

机译：公吨。玉龙是目前包括欧洲在内的欧亚大陆最南端的冰川覆盖地区。该山上有19个亚热带温带冰川，受西南季风气候控制。 1999年夏天，第一个核芯，rn10。在最大的冰川白水1号的堆积区中恢复了10 m长，一直延伸到冰川冰。在7. 8 m以上的深处，气候信号出现了周期性变化，并通过四年的时间确定了四年的净积累。同位素和离子组成的年度变化。较高的电导率和pH值，以及夏季表层的肮脏的再次冻结冰层，证实了年累积量的边界。从1994/1995年到1997/1998年的年平均净积累量约为900毫米水当量。剖面中同位素变化的幅度随深度的增加而减小，并且由于融化水的渗滤，在7. 8 m以下发生了同位素均质化。δ18O在7. 8 m以上的变化与丽江站的冬季气候趋势近似相关。，距离25公里。 Ca2 +和Mg2 +的浓度比Na +和K +的浓度高得多，表明降水的空气质量主要来自大陆来源，并且核心物质在冬季积聚。 C1-和Na +的密切对应关系表明它们共同的诺里金。 SO2-4和NO3-的浓度极低，表明该地区人类活动造成的污染非常低。核心区域的年均净积累量和估计的消融度表明，在冰川冰川平衡线以上的年平均降水量为2400-3150 mm，但这需要通过长期观察质量平衡来确认。

Isotopic and chemical analyses of a temperate firn core from a rnChinese alpine glacier and its regional climatic significance

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