冻结过程中硝酸盐在包气带中运移特征的试验研究  

Experimental Study on the Migration Characteristics of Nitrate in the Vadose Zone during the Freezing Process

作　　者：吴辉 刘晓敏 刘明柱[2] WU Hui;LIU Xiaomin;LIU Mingzhu(PowerChina Northwest Engineering Corporation Limited,Xi'an 710065,China;China University of Geosciences(Beijing),Beijing 100000,China)

机构地区：[1]中国电建集团西北勘测设计研究院有限公司,西安710065 [2]中国地质大学(北京),北京100000

出　　处：《西北水电》2024年第3期35-41,共7页Northwest Hydropower

基　　金：国家自然科学基金项目(41572225)。

摘　　要：为了探究包气带中硝酸盐在冻结过程中的运移规律,采用KNO_(3)作为典型污染组分,通过室内模拟试验,对温度、未冻水含量、溶液浓度等重点参数进行分析。结果表明:在试验条件下,剖面上垂向的水分运移比较明显,随着冻结锋面的下移,锋面处液态水含量变小,毛细负压减小,毛细力增强,导致下部的水分向上部移动,冻结封面的影响范围在10 cm左右,而且越靠近冻结锋面未冻水含量越小;未冻水含量与溶液浓度有着明显的负相关关系,在冻结过程中,随着固态冰的增多,未冻水含量减少,溶液中的溶质会往液态水中迁移,所以未冻水含量在减少的同时,溶液的浓度却在不断增大;溶液初始浓度0.3 mg/L,因为冻结过程而发生溶质迁移后的浓度为0.35~0.5 mg/L。In order to explore the migration law of nitrate in the vadose zone during freezing,using KNO_(3)as a typical pollution component,key parameters such as temperature,unfrozen water content,and solution concentration are analyzed through indoor simulation experiments.The results show that under the experimental conditions,the vertical water migration on the profile is quite obvious.As the freezing front moves downward,the liquid water content at the front decreases,the capillary negative pressure decreases,and the capillary force increases,causing the water in the lower part to move upward.The influence range of the freezing cover is about 10 cm,and the closer to the freezing front,the smaller the unfrozen water content;the unfrozen water content has a significant negative correlation with the solution concentration.During the freezing process,as the solid ice increases,the unfrozen water content decreases,and the solute in the solution migrates to the liquid water.Therefore,while the unfrozen water content decreases,the concentration of the solution continues to increase;the initial concentration of the solution is 0.3 mg/L,and the concentration after solute migration due to the freezing process is 0.35~0.5 mg/L.

关 键 词：地下水 硝酸盐 包气带 冻结作用 溶质运移 

分 类 号：X523[环境科学与工程—环境工程]