地下咸水作用下水库咸化特征研究

Study on Salinization of Reservoir under the Influence of Saline Groundwater

水库水质咸化会影响居民生活用水、农业灌溉、水资源的可持续利用等,但关于地下咸水对水质咸化的影响少有研究。该文以天津滨海地区北大港水库为研究对象,通过室内土柱试验,分析地下咸水对不同采样点库水TDS和Cl-的垂直动态变化和水文地球化学变化的影响,揭示水库咸化机理。试验结果表明:通入地下咸水后,TDS和Cl-浓度变化均会经历3个阶段:静置期-上升期-动态平衡期。静置期(通入地下咸水后的7 d内),TDS和Cl-浓度没有明显的变化,7 d后会经历约30 d的快速上升阶段,并在后期达到动态平衡。垂直方向上呈现浓度梯度,存在扩散边界层,底层TDS和Cl-浓度最大,边界层内的浓度变化比边界层外的大,10 cm深度的TDS浓度为13.59ρ0和4.52ρ0,30 cm深度的TDS浓度为6.82ρ0和1.97ρ0。TDS和Cl-的释放通量经过波动期(1~14 d)-上升期(15~44 d)-下降期(45~106 d)。离子比例分析表明水化学组分来源主要有蒸发盐岩、碳酸盐岩和硫酸盐等矿物溶解风化。

Salinization of reservoir will affect domestic water,agricultural irrigation and sustainable utilization of water.Previous research focused on the salt release of sediment.There are few researches on the influence of groundwater on salinization of reservoir.This study took Beidagang Reservoir in Tianjin as the research area and conducted the indoor column experiment using reservoir water at different sampling points.This study analyzed the vertical dynamic change law of TDS,Cl-and hydrogeochemical changes to reveal the mechanism of salinization of reservoir.The results show that TDS and Cl-went through three periods:the resting periods,the rising periods and the dynamic equilibrium periods.In the first week after the injection of groundwater,there are no significant changes in TDS and Cl-concentration.After one week,it went through the rapid rising period about 30 days and reached the dynamic equilibrium period at a later stage.There was a concentration gradient in the vertical direction with the highest concentration of TDS and Cl-in the bottom layer.There was a diffusion boundary layer and the concentration in the boundary layer changes more than that outside the boundary layer.The TDS concentrations at 10cm depth are 13.59ρ0 and 4.52ρ0,and those at 30cm depth are 6.82ρ0 and 1.97ρ0.The release fluxes of TDS and Cl-went through three stages:fluctuation stage(1~14 d),rising stage(15~44 d)and descent stage(45~106 d).The ions ratio indicated that hydrochemical component derived from evaporite,carbonate rock and sulfate minerals.