新疆塔里木盆地灌区地下水水质空间变化及其影响因素

Spatial Change in Groundwater Quality and Its Determinants in Irrigation Areas at Tarim Basin,Xinjiang

【目的】研究新疆塔里木盆地灌区地下水水质空间变化及影响因素。【方法】依据1292组地下水水质检测资料,通过描述性统计分析方法和Piper三线图解法分析地下水化学组分特征及水化学类型,采用水质指数法、USSL图和Wilcox图解法对灌区地下水水质进行了评价,运用克里金插值法、因子分析和离子比值等方法对灌区地下水水质空间变化及其影响因素进行了分析。【结果】山前砾质倾斜平原区地下水质量优于中下游的细土平原区,地下水从山前砾质倾斜平原区流动到细土平原区的过程中,经过岩石的溶滤作用,致使地下水中离子量增多,水质逐渐趋于劣化。灌区地下水可溶性盐浓度过高,通过强烈的蒸发作用使埋藏较浅的地下水中的盐类离子析出,使得盐分积聚地表,会加重土壤盐渍化;灌区地下水水质优劣排序为:单一结构潜水>承压水>承压水区潜水。【结论】灌区地下水水质受蒸发浓缩和矿物溶解的复合作用、原生地质的氧化还原环境以及人为活动的影响,除此之外,还受到含水层类型、地下水补径排条件和阳离子交换作用的影响。

【Objective】This paper is to analyze the spatial change in groundwater quality and its determinants in irrigation areas in Tarim Basin in Xinjiang,in attempts to provide a baseline guidance for sustainable utilization of groundwater resources and alleviating groundwater pollution.【Method】The analysis was based on 1292groundwater quality measurement data,from which we analyzed the groundwater chemical composition and chemistry types using the descriptive statistical analysis method and the Piper trilinear diagram method.The groundwater quality was analyzed using the water quality index method,USSL diagram and Wilcox diagram;spatial variation in groundwater quality and its determinants were calculated using the Kriging interpolation,factor analysis and ion ratio methods.【Result】Groundwater quality in the gravelly inclined plain in front of the mountain was better than that in the fine soil plain in the middle and low reaches of the basin.Dissolution of rocks increased ion contents in the groundwater,and groundwater quality deteriorates gradually from the gravelly inclined plain to the fine soil plain.The soluble salt concentration of groundwater in irrigation areas was considerably high;ions in shallow groundwater precipitated due to evaporation,resulting in salt accumulation on the soil surface.The factors affecting groundwater quality are ranked in the order:single structured unconfined groundwater>confined groundwater>unconfined groundwater in confined area.【Conclusion】The groundwater quality in the irrigation areas was jointly affected by evaporation and mineral dissolution,the redox in original geology,and human activities,in addition to aquifer type,groundwater recharge-discharge,runoff and cation exchange.