| 巴尔喀什湖流域水化学和同位素空间分布及环境特征 |
| 摘要点击 2257 全文点击 730 投稿时间：2019-05-29 修订日期：2019-08-06 |
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| 中文关键词 巴尔喀什湖流域 伊犁河 不同水体 水化学 氢氧同位素 |
| 英文关键词 Lake Balkhash basin Ili River water samples hydrochemistry hydrogen and oxygen isotopes |
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| 中文摘要 |
| 巴尔喀什湖位于哈萨克斯坦境内，是世界上最大的湖泊之一.伊犁河是巴尔喀什湖的主要补给河流，也是中哈两国重要的跨境河流.通过数理统计、Piper三线图、Gibbs模型和主成分分析（PCA）等方法，对巴尔喀什湖流域不同水体的化学参数和氢氧稳定同位素（δD和δ18 O）进行分析，初步研究了该区域水化学类型和同位素空间分布特征，探讨了其形成原因和环境意义.结果表明，不同水体的水化学类型不同，湖泊水体的主要化学类型为SO4-Na和Cl-Na，入湖河流的水化学类型为HCO3-Ca型，其中伊犁河水化学类型从上游到下游由重碳酸盐型过渡到硫酸化物型、氯化物型；Gibbs图显示湖泊水体离子组成位于蒸发作用区，河流水体离子组成位于蒸发作用和岩石风化作用之间，伊犁河从上游到下游向蒸发控制带偏移，反映了上游河水受降水、冰雪融水的补给影响较大，而下游水体受蒸发作用影响较大；此外，PCA分析指示人类活动对湖泊、伊犁河中下游和其他入湖河流水化学的影响.湖泊和河流水体的氢氧同位素组成变化差异较大，湖泊水体氢氧同位素偏正，位于全球大气降水线和哈萨克斯坦地区蒸发线之间，氘盈余小于全球降水线，反映了较强的蒸发作用导致湖水同位素富集；河流水体的氢氧同位素位于全球降水线附近，河流水体的氢氧同位素关系方程的斜率（伊犁河：5.7，其他入湖河流：3.1）均低于全球降水线（8），表明降水和蒸发过程影响河流水体同位素组成.湖泊水体化学参数和同位素显著相关，尤其是东部水体，表明强烈的蒸发作用同时导致水体同位素的富集和水化学离子的浓缩. |
| 英文摘要 |
| Lake Balkhash is one of the largest lakes in the world. It is located in arid Central Asia and receives major water from the Ili River, which is an international river flowing across China and Kazakhstan. Hydrochemical and isotopic measurements of waters can provide an improved understanding of hydrogeochemical processes and environmental characteristics, which is useful for water resource management in arid regions. In this study, δD, δ18 O, and major ions in water samples from the Lake Balkhash catchment were analyzed using an integration of mathematical statistics, Piper diagrams, Gibbs model, and principal component analysis (PCA). Water types and main mechanisms controlling the hydrochemistry presented a clear spatial heterogeneity. The chemical composition of lake waters was dominated by SO4-Na and Cl-Na type, whereas river waters were classified as a HCO3-Ca type. The chemical composition downstream of the Ili River evolved from HCO3-Ca to SO4-Na-Cl type. Gibbs model suggested that the main mechanisms controlling the lake water chemistry were evaporation-crystallization processes, and that major ions in the river water were affected by rock-weathering and evaporation processes. The main controlling factors of the water chemistry changed from the upstream to the downstream, and may have related to spatial differences whereby the upstream area experienced higher rainfall and snow melt, and the downstream area experienced relatively higher evaporation. PCA analysis showed that human activities also played an important role in the chemical composition of water sampled from the lake, middle and lower reaches of the Ili River, and other rivers. The isotopic compositions of the lake and river waters varied spatially. In the lake waters, positive isotopic ratios and negative deuterium-excess values indicated that evaporitic enrichment dominated the changes in the isotopic signature of the lake water. In river waters, isotope values located near the global meteoric water line (GMWL) and lower slopes of the regression lines (r=0.91, P<0.001 for Ili River, and r=0.63, P<0.001 for other rivers), were associated with a stronger influence of rainfall and weaker evaporation. Correlation analysis showed that there were significant relationships between isotope values and chemical parameters in the lake water, especially in the eastern area, thus suggesting that extensive evaporation led to simultaneous enrichment of isotopes and ions in the lake water. |
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