中国内陆干旱、半干旱区苦咸水分布特征

通过大量野外调查、水样采集和化验分析，对中国内陆干旱、半干旱区的苦咸水和高氟水分布特征进行了初步研究。采集到的地表和地下水样中，分别有51.0%和41.5%属于苦咸水；55%和59%水样氟化物含量超标，属于高氟水。研究区的苦咸水以Cl^--Na⁺和HCO₃^--Na⁺为主要离子类型，SO₄^2--Mg²⁺和SO₄^2--Ca²⁺为次要离子类型。苦咸水和高氟水主要分布在内陆河流域下游尾闾、封闭内流区低洼湖盆低地、北部准平原化干燥剥蚀低山残丘间冲积洼地、沙漠低洼湖盆和黄土高原中西部径流系数较小的河流及部分露头潜水等区域，并具有区域富集性分布特点。季节性降水、季节性河流或渠系灌溉对苦咸水的季节性或年际间变化和空间分布有较大影响。较高浓度基质含盐量、水文地质结构、气候条件和特定的水文地球化学环境是苦咸水和高氟水形成与富集分布的主要原因。

Characteristics and Distribution of Brackish Water in Arid and Semi-arid Interior of China

By surveying in large areas, sampling and laboratory testing in recent years, the characteristics and distribution of brackish water in the arid and semi-arid interior of China were investigated thoroughly. The results of water chemical analysis showed that 51.0% and 41.5% of surface and groundwater samples respectively exceede the threshold of Brackish water, and 55% and 59% exceed the threshold of high-fluorid water, with the primary and secondary ions of Cl^--Na⁺, HCO₃^--Na⁺ and SO₄^2--Mg²⁺, SO₄^2--Ca²⁺ respectively, implying that the brackish and high-fluorid water were distributed widely in the studied area. Spatially, the brackish water and high-fluorid water were distributed in the lower reaches of inland river of the Hexi Corridor, lower land of deserts and intervals of western Inner Mongolia, western Loess Plateau, and Ordos Plateau. It was characterized by enrichment distribution of fluorid and some primary ions such as Na⁺, Cl^-, and some secondary ions such as SO₄^2-, Mg²⁺. There are several factors which conduces brackish water and high-fluorid water wide distribution in the studied area, such as higher salty content in aquifers, the hydrogeological construction, climatic condition and special geochemistry surroundings. Nevertheless, seasonal rainfall and runoff, irrigating water may influence on the variability of the content of total dissolved solids, sulphate and fluorid and the spatial distribution of brackish water and high-fluorid water in arid and semi-arid interior of China.