基于氢氧同位素和水化学的祁连山老虎沟冰川区径流过程分析

基于2012-2013年两个消融期在祁连山老虎沟冰川区连续2 a采集的冰川融水径流、雪冰以及降水样品,分析探讨了冰川区水体介质中氢氧同位素和水化学要素(主要化学离子、pH值、TDS和电导率等)在消融期的变化过程及特征。结果表明:祁连山老虎沟雪冰融水中的氢氧同位素值(δD和δ¹⁸O)表现出明显的消融期随月份波动,先升高再降低的趋势,在7月份表现出高值,反映了冰川消融强弱程度的变化过程。冰川径流中同位素含量与冰雪融水接近,且处于当地降水线上,其主要来自冰雪融水和降雨补给。老虎沟冰川融水径流水化学主要表现为Ca-Na-HCO₃-SO₄和Ca-Mg-HCO₃-SO₄型,其组成特征也表现出随消融过程而变化。对氢氧同位素和化学要素组成在消融期(6~9月)随时间的变化过程进行了分析,表明结合冰川区氢氧同位素和化学要素(包括化学离子、TDS、pH值和电导率等)的组成可以区分雪坑和新雪、河水的组分变化,可以反映冰川融水径流在消融期的变化过程。

Glacier meltwater runoff process analysis based on δD and δ18O isotope and chemistry in the Laohugou glacier basin of the Qilian Mountains

Stable hydrogen and oxygen isotope is important on water transportation tracing research. Based on stable hydrogen and oxygen isotope using a Picarro L1102-i(V-SMOW standard)and water chemistry(e.g., major ions, pH and EC, TDS)measurement with Dionex-600 and Dionex-300, this paper discussed the variation and characteristics of stable hydrogen and oxygen isotope, chemistry(TDS, pH, EC, Ca²⁺, Mg²⁺, Na⁺, and Cl^-) in the glacier meltwater, ice and snow, and precipitation in the Laohugou glacier basin during 2012-2013. Result showed that δD and δ¹⁸O in the glacier melt runoff varied obviously with the temporal change from June to September, firstly with increase trend and then with decrease trend, and highest value in July with the highest air temperature and strong glacier melting, indicating the glacier melting process and extent. δD and δ¹⁸O in the runoff is similar with that of snow and ice on the glacier, and is also above the LMWL, which is probably imply the hydrogen and oxygen isotope is mainly originated from glacier melting and precipitation supply. The glacier meltwater type of Laohugou glacier basin are mainly composed by Ca-Na-HCO₃-SO₄ and Ca-Mg-HCO₃-SO₄, which also varied with the glacier melting process in summer. By analyzing the temporal change of stable hydrogen and oxygen isotope and chemistry in melting period, it is easy to separate the components of the snow and ice and melt-runoff in the river, which could reflect the change of glacier melting process during the melting period, and thus this work can contribute to the glacier runoff change study of large scale region by stable isotope and geochemical method in future.