咸水冰融化与土壤入渗过程不同盐分离子迁移规律研究

通过模拟试验及大田试验研究了咸水冰融化过程及土壤入渗过程不同盐分离子迁移分布规律,以期揭示咸水冰融水水质变化机理及咸水结冰灌溉对土壤盐分分布的影响。试验结果表明,咸水冰融化过程各离子含量均急速下降,但不同离子融出速度不同,各离子融出比例高低次序为Cl->Mg2+>K+>Na+>SO42->Ca2+>HCO3-;离子融出速度的不同,导致融水离子组成发生变化,最终使融水钠吸附比下降,pH值上升。咸水结冰灌溉使0～80 cm土体中除HCO3-增加6.85%以外,其余各离子均表现为下降,各离子淋出比例由高到低为Mg2+>Cl->Ca2+>Na+>K+>SO42->HCO3-;Cl-、Na+淋出比例不是最高,但在总淋出盐分中所占的比例分别达到了62.01%和21.96%。咸水结冰灌溉改变了土壤的离子组成,使土壤表层产生碱化趋势,因此,咸水结冰灌溉应当配合一定措施防止土壤碱化。

Study on Migration of Different Salt Ions in Melting and Infiltration Processes of Saline Water Ice

Simulation and field experiments were conducted to investigate the migration of different salt ions in melting and infiltration processes of saline water ice.The aim of these experiments is to reveal the mechanism of water quality changes in ice melting and the distribution of different ions in different soil depth.The results showed that the content of all salt ions decreased rapidly during ice melting process.However,different ions leached in different rate.The sequence of different ions leaching ratio from high to low was Cl->Mg2+>K+>Na+>SO42->Ca2+>HCO3-.The difference of ions leaching rate leaded to changes of ions composition in melted water,which reduced sodium adsorption ratio and increased water pH eventually.After irrigation with freezing saline water,all salt ions of soil(0~80 cm)were decreased except HCO3-,which increased by 6.85%.The sequence of ions leaching ratio from high to low was Mg2+>Cl->Ca2+>Na+>K+>SO42->HCO3-.Although the leaching ratios of Cl-and Na+ were not the highest,their proportions reached 62.01% and 21.96% in total leaching salt,respectively.Irrigation with freezing saline water changed the ion composition of soil and resulted in alkaline trend in the surface soil.Therefore,freezing irrigation with saline water should be assorted with some measures to prevent soil alkalization.