北疆地区的水化学组成特征及其影响因素

流域尺度上的水化学组成特征和来源会受到何种因素的影响和限制,是研究区乃至全球环境变化的焦点问题,需要综合考虑不同地表要素和环境下的天然水体来揭示其答案。本文选择北疆地区的三大水系（伊犁水系、准噶尔水系、额尔齐斯水系）开展水化学组成研究,以期认识中亚造山带中部干旱环境下典型水系的水化学组成特征、成因及其影响因素。本研究利用已采集的北疆三大水系天然水样品及其水化学组成分析数据,同时系统收集了北疆及其周边地区文献资料,并与其他中纬度地区和国际典型气候带地区进行了综合对比。综合数据分析结果表明,北疆水系的河流溶解性固体总浓度（TDS值）普遍高于中国季风区和湿润地区河流,也高于世界平均水平;水体的主要阴阳离子分别以Ca²⁺和HCO₃^-占主导地位;主量离子间相对浓度与中国东部季风区河流类似,也与世界大部分以碳酸盐岩风化为主导的河流相似。岩石风化作用在水化学成因上对北疆大部分地区都占据主导地位;进一步定量的结果发现,不同来源对天然水溶质贡献量大小的顺序为：蒸发岩溶解>碳酸盐岩风化>硅酸盐岩风化>大气降水,证明了蒸发岩溶解和碳酸盐岩风化的主导地位。对比硅酸盐岩风化与碳酸盐岩风化,北疆水系的中低地形区硅酸盐岩影响更大,海拔较高的山地地区则碳酸盐岩影响更大。区域降水、水热组合、径流、岩性等因素都对水化学过程产生重要的影响,但与温度的关系不明显,与流域物理侵蚀过程及其季节变化等的关系尚不明确,需要开展进一步的研究工作。

Hydrochemical characteristics and influencing factors in Northern Xinjiang: Research progress and overview

It is a controversial scientific problem that what factors affect and restrict the characteristics and sources of water chemistry at a watershed scale. To get the answer, it is necessary to integrate the natural water bodies in different geographical units and specific environments. In this paper, three hydrological systems (Yily, Junggar and Erlqis) in Northern Xinjiang were selected to carry out hydrogeochemical research, in order to understand the hydrochemical characteristics, causes and influencing factors of typical drainage systems in the arid environment of the Central Asian Orogenic Belt (CAOB). Based on the natural water samples we collected the three drainage systems in Northern Xinjiang, and used their hydrochemical data of the subsequent analysis, together with the hydrogeochemical data newly collected in this study from the latest Chinese and Western scientific literatures focused on the study area and its surroundings as well as other typical catchments in the world, to made comprehensive intra- and inter-regional comparisons between the study area and other middle-latitude regions and typical climate zones. The results show that the total dissolved solid concentration (TDS) of rivers in Northern Xinjiang water system is generally higher than that of rivers in monsoonal and humid regions of China, and also higher than the world average level. The main cation and anion of the water body are dominated by Ca²⁺ and HCO₃^-, respectively. The relative concentration of major ions in the study area is similar to that of rivers in the eastern monsoon region of China, and similar to most of rivers dominated by carbonate weathering in the world. Rock weathering plays a dominant role in most parts of Northern Xinjiang in terms of hydrochemical genesis. Further quantitative result shows the order of solute contribution from different sources to natural water: evaporite dissolution > carbonate weathering > silicate weathering > atmospheric precipitation, which fully proves the dominant position of evaporite dissolution and carbonate weathering. Compared with the weathering situation between silicate and carbonate, the influence of silicate is greater in the middle and low terrain areas of Northern Xinjiang drainage systems, while the influence of carbonate is greater in mountainous areas with higher elevations. Regional precipitation, hydrothermal combination, runoff and lithology all have important impacts on the hydrochemistry of drainage systems of the study area, but the relationship with temperature is not obvious, and the relationship with physical erosion process of the basins is not clear, which requires further research.