引黄灌溉入渗条件下的地下水化学演变特征

Variability Characteristics of Groundwater Chemical Under Condition of Yellow River Diversion and Recharge

研究引黄灌溉入渗引起的地下水化学变化特征,对区域地下水水质调节和改善有着积极的指示作用。通过田间原位入渗试验,进行水田、旱田回灌过程中回灌水-地下水监测和分析,利用AquaChem水化学分析和SPSS数理统计揭示地下水化学演变规律。由试验可知,地下水化学变化特征呈现“前期骤变活跃带—中期渐变过渡带—后期平缓稳定带—停灌潜在回升带”四个演变过程,主要受回灌水的物理混合作用,伴随着水-岩物理吸附离子交换、化学溶解和溶滤等作用,特别是水田的回灌水量大,回灌水决定了地下水化学演变方向;同时,受水-岩溶滤作用,地下水化学组分Na^(+)、Cl^(-)浓度有较好的线性变化,相关系数在0.93以上,Ca^(2+)、Mg^(2+)与SO_(4)^(2-)、HCO^(-)_(3)浓度有一定的线性相关性;在停灌后,地下水蒸发浓缩作用强烈,水中各离子呈增加趋势,特别是Na^(+)、Cl^(-),停灌后需及时排水、降水。研究表明引黄灌溉不仅丰富了地下水水源,而且可以改善地下水水质。

The study of groundwater chemical varieties has a positive indicator effect on the regulation and improvement of regional groundwater quality caused by infiltration in the Yellow River Irrigation Area.The field in-situ infiltration test was carried out to monitor and analyze the recharge water-groundwater during the recharge process of paddy field and dry field,and the groundwater chemical evolution law was revealed by AquaChem hydrochemical analysis and SPSS mathematical statistics.Under the condition of infiltration,the characteristics of groundwater chemical change show four evolution processes:"rapid change and active zone in the early stage,gradual transition zone in the middle stage,gentle and stable zone in the late stage,and potential recovery zone after stopping irrigation".It can be seen from the experiment that the groundwater is mainly affected by the physical mixing of recharge water,accompanied by the water-rock physical adsorption ion exchange,chemical dissolution and leaching,etc.especially,the amount of recharge water in paddy field was large,and the water quality of recharge determined the direction of groundwater chemical evolution.At the same time,the concentrations of Na~+、Cl~- of groundwater chemical components showed a good linear change,and the correlation coefficient was above 0.93,and the concentrations of Ca~(2+)、Mg~(2+) showed a certain linear correlation with SO_4~(2-)、HCO~-_3.After stopping irrigation,the evaporation and concentration of groundwater was strong,and the ions of groundwater showed an increasing trend.Especially for Na~+、Cl~-,the drainage and precipitation are timely needed after the irrigation.The research shows that the water supply of groundwater not only enriched groundwater sources,but also improved groundwater quality.