引用本文:李 慧,林 青,徐绍辉.咸水/微咸水入渗对土壤渗透性和盐分阳离子运移的影响[J].土壤学报,2020,57(3):656-666. DOI:10.11766/trxb201906180279
LI Hui,LIN Qing,XU Shaohui.Effect of Infiltration of Saline Water/Brackish Water on Soil Permeability and Transport of Salt Cations in the Soil[J].Acta Pedologica Sinica,2020,57(3):656-666. DOI:10.11766/trxb201906180279
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咸水/微咸水入渗对土壤渗透性和盐分阳离子运移的影响
李 慧, 林 青, 徐绍辉
青岛大学环境科学与工程学院
摘要:
在淡水资源短缺的干旱、半干旱及滨海地区,地下微咸水/咸水资源较为丰富。为保障粮食安全和农业可持续发展,需利用微咸水/咸水进行合理灌溉,以缓解淡水资源短缺状况。与此同时,微咸水/咸水灌溉入渗,会引起土壤物理、化学及生物等性质的变化。通过室内土柱出流试验,探讨了灌溉水盐分种类和浓度对土壤渗透性能及盐分阳离子运移的影响。选用灌溉水盐分种类为NaCl、 MgCl2、 CaCl2,浓度为3 g·L-1、5 g·L-1(代表微咸水)、10 g·L-1(代表咸水)。结果表明:土壤对微咸水与咸水的响应机理基本一致,Na+在土壤中的迁移会导致土壤渗透性的降低;Ca2+、Mg2+在土壤中的迁移会提高土壤的渗透性;且三种离子对表层土壤的影响均大于下层土壤。土壤相对渗透系数K/K0K为各时刻计算所得的渗透系数,K0为初始渗透系数)减小程度与Na+浓度成正比;Ca2+、Mg2+ 对土壤渗透性能的影响相似,土壤相对渗透系数增加的程度与Ca2+、Mg2+ 浓度成反比,其中Ca2+对提升土壤渗透性的能力强于Mg2+;不同条件下土柱整体相对渗透系数与时间及离子浓度均成二次方相关关系;在NaCl溶液入渗过程中,土壤中被置换出来的Ca2+、Mg2+含量随着NaCl溶液浓度的升高而增加,而且随着入渗深度的增加而增大;土壤含盐量取决于入渗水的种类和浓度,在灌溉过程中容易发生土壤积盐的情况,入渗溶液浓度越高,积盐越严重。研究结果对合理开发利用咸水/微咸水灌溉具有一定指导意义。
关键词:  咸水灌溉  盐分  渗透系数  迁移  离子沉积
基金项目:国家自然科学基金项目(41571214,41807010)资助
Effect of Infiltration of Saline Water/Brackish Water on Soil Permeability and Transport of Salt Cations in the Soil
LI Hui, LIN Qing, XU Shaohui
College of Environmental Science and Engineering,Qingdao University
Abstract:
【Objective】 In the arid, semi-arid and coastal regions where freshwater resources are scarce, while underground brackish water/saline water resources are abundant. In order to ensure food security and sustainable development of the agriculture development, it is necessary to use brackish water/saline water for reasonable irrigation to alleviate the pressure of shortage of freshwater resources. However, the use of brackish water/saline water for irrigation will certainly cause accumulation of salts in the soil, and trigger secondary salinization of the soil, thus affecting growth of the crops therein. Moreover, it will also alter chemical composition of the soil solution and stability of the soil structure, leading to degradation of soil physical properties and change in chemical reaction in the soil. 【Method】 In this paper, an indoor soil column percolation experiment was conducted to investigate effects of the salts in irrigation water, relative to kind and concentration, on permeability of and transport of salt cations in the soil. In the experiment, to prepare soil columns, plexiglass cylinders, 40 cm in height and 6 cm in diameter, were used, and for irrigation water containing NaCl, MgCl2 and CaCl2, separately, at 3, 5 g·L-1 (as brackish water) and 10 g·L-1 (saline water). A total of 9 treatments were designed, and each had two replicates. 【Result】 It was found that soil relative permeability coefficient K/K0 (K stands for permeability coefficient calculated at each time, and K0 for initial permeability coefficient) decreased with the increasing of Na+ concentration, and permeability declined faster in the topsoil than in the lower soil layers; and Ca2+ and Mg2+ behaved similarly during the process of infiltration, that is, both increasing soil permeability by a rate rising with the increase in Ca2+ and Mg2+ concentration and in soil depth. The effect of Ca2+ was more significant than that of Mg2+. Relative permeability coefficient of the whole soil column was in quadratic relationship with time and ion concentration. In terms of conductivity of soil effluent , the treatments followed an order NaCl > CaCl2 > MgCl2, while in terms of pH, an order of NaCl > MgCl2 > CaCl2. In the columns treated with NaCl solution, both Ca2+ and Mg2+ increased in the soil with rising NaCl concentration in the solution and soil depth. 【Conclusion】 Na+ migration in the soil will leads to decrease in soil permeability; while Ca2+ and Mg2+ migration in the soil does reversely; and the effects of the three ions are more significant in the surface soil layer than in the lower layers. Salt content in the soil depends on kind and concentration of the infiltration water. Irrigation with saline/brackish water tends to lead to accumulation of salts in the soil. The higher the salt concentration in the irrigation water, the higher the salt accumulation. When using saline/brackish water for irrigation, it is advisable to arrange irrigation reasonably in the light of water quality and properties of the soil to be irrigated, coupled timely with certain soil amelioration measures, when necessary, so as to avoid any adverse impacts of the irrigation on soil permeability and crop growth.
Key words:  Salt water irrigation  Salt  Permeability coefficient  Migration  Ion deposition