玉龙山温冰川浅冰芯内气候环境信息的初步剖析

Preliminary Analysis of Climatic and Environmental Signals of a Shallow Ice core from a Chinese Temperate Glacier in Mt. Yulong

稳定同位素和离子分析结果表明 ,我国青藏高原东缘玉龙山温冰川的一支浅冰芯内的大部分气候环境信息有良好的对应关系 ,可揭示近期若干年冰川净积累时期内的气候变化趋势和冰川的净积累量 ,且与当地实测气候资料相对应 .该浅冰芯的研究也揭示出冬夏季风和融水渗浸作用对冰芯气候记录的影响过程 ,表明温冰川气候环境信息的时间序列有限 .温性冰川浅冰芯现代过程的分析为研究西南季风环流的动态变化提供了一个新的重要途径 .

Mt. Yulong is a present glacialized area southmost both in China and Eurasia continent,where lie 19 typical sub tropical temperate glaciers controlled by the climate of southwestern monsoon. In the summer of 1999, a firm core, 10 10 m long to the glacier ice, was recovered in the accumulation area at the largest glacier Baishui No.1 in Mt. Yulong. Periodic variations of the climatic signals above the depth of 7 8 m in the core are apparent and fouryears net accumulations were identified by the annual oscillations of isotopic and ionic composition. The boundaries were also confirmed by some higher values of electrical conductivity and pH, and the position of dirty refrozen ice layers on the level of summer surfaces for the above years. Average annual net accumulations from 1994/1995 to 1997/1998 were calculated to about 900 mm water equivalent. The amplitude of isotopic oscillations in the profile was getting smaller with the increasing depth in the core and the isotopic homogenization occurred below the depth of 7.8 m, as a result of meltwater percolation. Changes of δ 18 O above 7 8 m in the core showed an approximate correlation to the winter climatic trend at Lijiang station during the fiveyears period. Concentrations of Ca 2+ and Mg 2+ were much higher than those of Na + and K +, indicating that the air masses for precipitation were mainly from a continental source and the materials of the core were accumulated during the winter period. Cl - and Na + show a corresponding relationship,indicating their same genesis. Very low concentrations of SO 4 2- and NO 3 - suggest that the pollution caused by human activities is quite low in this area.