银川地区地下水水化学特征演化规律及水质评价

Evolution of groundwater hydrochemical characteristics and water quality evaluation in Yinchuan area

研究地下水的水化学特征演化规律及水质评价,对地下水水资源保护和可持续开发利用具有重要意义.本文根据银川地区1991—2016年地下水水质监测资料,运用经典统计学、Piper三线图解法、Gibbs图解法、离子比值法对研究区地下水水化学特征及演化规律进行分析,并利用模糊综合评价法对研究区62个水样点进行水质评价.结果表明,26年来研究区地下水化学组分未发生明显变化,为偏碱性硬水.多年地下水中各离子含量排序一致,阳离子含量排序为:Na+>Mg2+>Ca2+>K+,阴离子含量排序为HCO-3> Cl->SO■.当前银川地区地下水水质基本满足生活饮用水的标准,山前冲洪积平原地区水质良好,丰登镇及北部地区水质最差,部分井孔的TDS大于2000 mg·L-1.地下水水质在1996年最差,自2006年以来得到明显改善.研究区地下水化学组分及水质受到水文地质条件、蒸发浓缩作用、岩石风化作用、补给水成分及人类活动的综合影响.

Studying the water chemistry evolution and evaluating groundwater quality are important significant for groundwater resources protection and sustainable development.Based on the groundwater quality monitoring data from 1991 to 2016 in Yinchuan area,we analyzed the hydrochemical characteristics and evolution of groundwater in the study area using classical statistics,Piper diagram,Gibbs diagram,and ion ratio analysis method,and also used fuzzy comprehensive evaluation method to evaluate water quality.The results showed that the chemical composition of groundwater in the study area has not changed significantly in the past 26 years,and it was alkaline water.The concentration of ions in groundwater were steady for many years.The order of cation was:Na+>Mg2+>Ca2+>K+,and the order of anion was HCO-3>Cl->SO■.At present,the groundwater in Yinchuan area basically met the standard of drinking water,and the water quality in the alluvial plain was good.The water quality in Fengdeng Town and the northern part was the worst,and TDS of some wells were greater than 2000 mg·L-1.Groundwater quality was the worst in 1996 and has improved significantly since 2006.The chemical composition and water quality of groundwater in the study area were affected by hydrogeological conditions,evaporation,rock weathering,recharge water composition and human activities.