天山冰川区山溪河水化学成分变化过程分析

2014年8月在天山北坡中段对玛纳斯河流域西部鹿茸冰川的考察中,采集了冰川表面融水径流至大南沟出山口以及流域内其他主要河流的水样共30个,从氢氧同位素关系、Gibbs图分析、水化学Pipper图分析以及相关分析,定量分析了由冰川、降水补给源到出山口的径流不同离子的变化特征和影响因素。结果表明:海拔2 000 m以上高山地区的河水均属TDS(total dissolved solids,总溶解固体)小于100 mg·L~(-1)的低矿化度甘甜淡水。河水呈弱碱性,p H介于6.92~7.86,与TDS、EC具有较好的相关性。河水含有的主要阴阳离子浓度为:HCO_3~-SO_4~(2-)NO_3~-Cl~-;Ca~(2+)Na~+Mg~(2+)K~+。各离子含量整体随着与河床接触时间增加和水流延伸而缓慢增大,不同离子变化过程存在差异。河床岩石成分和离子间复杂的相互作用是导致差异的主要原因。其影响力为:水岩作用降水贡献蒸发浓缩。硫酸盐岩贡献较大,导致SO_4~(2-)增加尤为明显;水化学类型由HCO_3~--Ca~(2+)型转化为(HCO_3~-、SO_4~(2-))-Ca~(2+)型。Cl~-、Na~+、Mg~(2+)、K~+等离子主要受到水化学相互作用的影响。NO_3~-主要来自人类活动和自然生物作用,F~-主要来自水-岩作用。

Changing Process of Hydrochemical Composition in Stream in Glacier Area,the Tianshan Mountains

In the investigation on Pilose Antler Glacier in the west Manas River Basin in middle northern slope of the Tianshan Mountains in August 2014,thirty water samples were collected from glacier-surface streams to the Danan Ditch Debouchure and other main rivers.A quantitative analysis on the variation of different ions and the affecting factors from glacier precipitation recharge source to the debouchure was carried out based on analyzing the relationship between the hydrogen and oxygen isotopes with Gibbs diagram analysis,hydrochemical Piper diagram analysis and correlation analysis.The results showed that river water in the mountainous area higher than 2 000 m a.s.l.was sweet fresh water with TDS lower than 100 mg · L-1.The river water was weakly alkaline,the pH value varied in a range of 6.92-7.86,and there was a good correlation between TDS and EC.The main anion and cation concentrations in river water were in orders of HCO3-＞ SO42-＞ NO3-＞ Cl-and Ca2+ ＞ Na+ ＞ Mg2+ ＞K+.The ion concentration in water was slowly increased downstream,and the change process was different from different ions.Such difference was mainly caused by the petrographic composition of riverbed rock and the complex interactions between ions.The effects of the affecting factors was in an order of water-rock interaction ＞ precipitation contribution ＞ concentration by evaporation.The contribution of sulfate rock was high,especially to SO42-increase,and the water chemical type was converted from HCO3--Ca2+ to (HCO3-,SO42-)-Ca2+ The Cl-,Na +,Mg2+ and K + concentrations were affected by hydrochemical interaction.NO3-came mainly from human activities and natural biological function,and F-was mainly derived from rock.