1.西北农林科技大学College of Water Resources and Architectural Engineering, Northwest A＆F University;2.Department of Hydraulic Engineering, Tongji University;3.College of Water Resources and Architectural Engineering, Northwest A＆F University;4.The Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Science
The 13th Five-Year Plan” National Key R&D Program of China (2017YFC0403302); Science and Technology Plan of Shaanxi Province (2020JQ-277)
为揭示微咸水结冰融水时咸淡分离状况及对盐渍土盐分的淋洗效应，通过室内融冰试验研究不同解冻温度(10、15 ℃)和矿化度处理(纯净水、0.5 g·L-1、2 g·L-1、4 g·L-1)冰体的融化速度及融出水质，并借助HYDRUS-1D模型，模拟分析了不同处理融出水与微咸水直接入渗对剖面土壤盐分的淋洗效果差异。结果表明：微咸水冰体咸淡分离效果明显，各处理下的微咸水冰体均有75 %以上淡水融出，矿化度越小融出淡水体积越大；微咸水冰体先咸后淡融出水入渗对盐渍土中的盐分有较好的淋洗效果，优于相同矿化度的微咸水直接入渗处理；10 ℃处理微咸水冰融出水对盐渍土的淋洗效果要好于15 ℃处理。研究成果对于探索内陆干旱区地下微咸水资源利用及新的非生育期节水控盐模式具有一定的指导意义。
Abstract: 【Objective】Soil salinization is of growing concern in China since it severely restricts agricultural development and poses ecological and environmental risks in arid and semi-arid regions. High soil salinity causes deterioration of soil physical and chemical properties and inhabits plant growth. Given the wide distribution of brackish groundwater in arid and semi-arid regions, brackish irrigation is an effective approach to mitigate the shortage of freshwater resources. In addition, the naturally low air temperature in winter makes it possible to combine brackish irrigation and freeze-melt processes to enhance salt leaching and thus help reduce soil salinity. 【Method】 To reveal the dewaterability of frozen brackish water, the melting rates and temporal changes in water quality of ice blocks frozen from brackish water were compared under two air temperatures (10 ℃, 15 ℃) and four initial salinity gradients (freshwater, 0.5 g·L-1, 2 g·L-1, and 4 g·L-1). Furthermore, to evaluate the salt leaching efficiency through saline soil by melted brackish water, the HYDRUS-1D model was applied to simulate the one-dimensional soil water and salt transport patterns under two scenarios: direct infiltration using brackish water and infiltration using desalinized water melted from brackish ice frozen at different initial salinity gradients.【Result】 Our results show that: (1) The amount of melting water per unit time of brackish water ice body increased first and then decreased, and the melting rate was faster and peaked at higher value when the initial salinity was greater; (2) Freeze-melt could effectively desalinize brackish water by selectively discharging brine with great salinity at the early stage of melting, and the dewaterability was greater at lower initial salinity with an average dewaterability > 75 %; (3) The HYDRUS-1D simulations on saline soil illustrated a better leaching efficiency when infiltrated with water melted from frozen brackish ice than directly applying unfrozen brackish water, and the leaching effect of brackish ice meltwater was better at 10 ℃ than at 15 ℃.【Conclusion】 These findings proved the applicability and effectiveness of combining brackish groundwater with freeze-melt treatments, as a new water-saving and salt-controlling mode, to help mitigate freshwater shortage and reduce soil salinization risk in the arid and semi-arid of China.
wangruiqi, lixianwen, zhengna, jiangsimin, chenjunying, yanbaowen, heyujiang. Dewaterability of Frozen-melt Brackish Water and Its Soil Salt Leaching Efficiency Based on HYDRUS-1D[J]. Acta Pedologica Sinica,,[In Press]