摘要
以西北地区第四纪黄土为研究对象,选择溴化钠和亚硝酸钠混合溶液作为原始水样,其中溴为示踪剂,研究NO_2^--N在一维土柱实验中的运移特征,实验结果表明:1Br^-与NO_2^-的浓度在流出液中表现出明显不同步的运移特征,示踪剂Br^-在运移过程中受到的影响可以忽略不计,而流出液中NO_2^-的浓度出现较大的延迟,延迟系数为2.5,可见土壤的吸附作用对NO_2^-的运移产生较大影响.2NO_2^-在流出液中的浓度也出现了一些变化,即达到平衡状态后的浓度略低于初始浓度,根据对流出液中pH值的同步监测结果可以认为,在p H值在6~8的土壤环境中,小部分N发生的硝化或反硝化作用使得平衡状态下NO_2^-的浓度出现偏低的状态.因此,除了土壤本身对NO_2^-的吸附作用影响NO_2^-在土柱实验的运移特征外,化学转化也构成了NO_2^-在土柱实验中的一个重要的运移特征.3在本次研究中,由于NO_2^-在运移过程中的特殊变化,电导率在流出液中的监测结果相比于Br^-也出现了一定程度的延迟,因此,在使用电导率进行土柱实验示踪时,应当考虑不同离子存在状态下的电导率的延迟效应.
The authors choose the Quaternary loess（ northwest of China）as the research object, the mixture solution of sodium bromide and sodium nitrite as initial solution, in which the bromine is the tracer, to study the migration characteristics of NO2^- - N in vertical soil column. The results are as follows. ①The concentration of Br^- and NO2^- - N in the outflow solutions shows that the characteristics of migration are not synchronized. The influence of Br^- concentration is negligible in the migration process by the soil; the concentration of NOf in the out- flow solution has a retardation phenomenon ; the retardation coefficient is 2.5 ; and the sorption of soil affects the migration characteristics of NO2^-. ②In the outflow solutions, when the values of NO2^- concentration become sta- ble, these values are lower than the initial concentration. Considering the results of pH value in the outflow solu- tions, in the soil environment whose pH value is between 6 to 8, this phenomenon are affected by the small part of N nitrification or denitrification. NO2^- finally is partly converted into NO3^- or NH4^＋ salt. Therefore, besides the sorption of soil, the chemical reaction is another important characteristic in the migration of NO2-. ③In this research, due to the existence of NO2^-, the conductivity of outflow solutions has some retardation, so if there are some ions in the soil column experiments, when using conductivity as an index of researches, the retardation coefficient of conductivity needs to be considered.
出处
《昆明理工大学学报（自然科学版）》
CAS
2016年第3期124-129,共6页
Journal of Kunming University of Science and Technology(Natural Science)
基金
中央高校重点实验室开放基金项目(CHD2013G1502045)
国家自然科学基金项目(41172212)
