| 摘要: |
| 针对城市污染河道是否需要清淤治理界线难以确定的问题，采用批平衡静态室内试验研究和Langmuir、Freundlich及Henry等温模型模拟的方法，以北京市通州区北运河土沟、榆林庄及和合站3个典型断面不同深度沉积物为研究材料，设定氨氮标准溶液质量浓度为20、40、80、160、200、320、400和600 mg/L 8个梯度，对氨氮的吸附和解吸热力学行为进行研究。结果表明：1） Langmuir、Freundlich及Henry等温模型对吸附和解吸过程拟合较好，相关系数R2>0.85；2）各典型断面0~20、20~40和40~60 cm深度单位质量沉积物对氨氮的理论最大吸附质量分别为1 184.60~26 168.00、343.46~648.00和228.10~462.05 mg/kg，0~20 cm吸附潜力最大；理论最大解吸质量分别为178.11~367.52、98.45~329.62和78.58~148.51 mg/kg，0~60 cm解吸潜力差异较小；3） Langmuir等温模型吸附常数kL大小关系为kL （0~20 cm）<kL （20~40 cm）<kL （40~60 cm），Freundlich等温模型吸附常数n大小关系为n（0~20 cm）<n（20~40 cm）<n（40~60 cm），沉积物越深，对氨氮的吸附性能越好；解吸比n大小关系为n（0~20 cm）<n（20~40 cm）<n（40~60 cm），沉积物越深，对氨氮的解吸程度越大；4）土沟断面0~40 cm深度沉积物对氨氮吸附-解吸临界状态的氨氮质量浓度大于上覆污染水体的氨氮质量浓度；榆林庄及和合站断面0~60 cm深度沉积物对氨氮吸附-解吸临界状态的氨氮质量浓度均小于上覆污染水体氨氮质量浓度。沉积物对氨氮的吸附-解吸过程存在动态平衡，所得动态模式和参数可为河道清淤治理提供理论指导。 |
| 关键词: 城市河道 沉积物 氨氮 吸附 解吸 沉积物深度 |
| DOI：10.11841/j.issn.1007-4333.2017.07.010 |
| 投稿时间：2016-06-30 |
| 基金项目:水利公益性行业科研专项（201401054） |
|
| Study on the adsorption/desorption characteristics of different depth sediments for ammonia nitrogen in urban river |
|
HU Jieyun, LI Shuqin, LI Yunkai, LANG Qi, DING Can
|
| (College of Water Resources & Civil Engineering, China Agricultural University, Beijing 100083, China) |
| Abstract: |
| In view of the problem that it is difficult to determine whether or not need dredge to govern urban polluted river,indoor research of batch equilibrium static and the Langmuir,Freundlich and Henry model simulation were conducted.And the research materials were sediments from different depths of three typical sections in North Canal,Tongzhou District,Beijing,including Tugou,Yulin Village and Hehe Station were taken as study materials.Thermodynamic behaviors of adsorption and desorption for ammonia nitrogen were studied under eight ammonia nitrogen solution concentration gradients of 20,40,80,160,200,320,400 and 600 mg/L.The results show that:1) Adsorption and desorption processes fitted well with the Langmuir,Freundlich and Henry model with correlation coefficient R2>0.85;2) The sediments' maximum adsorption capacities for ammonia nitrogen of typical sections,whose depth were respectively 0-20,20-40 and 40-60 cm,were 1 184.60-26 168.00,343.46-648.00 and 228.10-462.05 mg/kg. Therefore,0-20 cm sediments' adsorption potential was the biggest.And their maximum desorption capacities were 178.11-367.52,98.45-329.62 and 78.58-148.51 mg/kg,respectively.Thus,the 0-60 cm sediments' desorption potential had little difference;3) The adsorption constants of Langmuir model at different depths in ascending order was kL(0-20 cm),kL(20-40 cm) and kL(40-60 cm).The sort of n,which was adsorption constant of Freundlich model in ascending order was n(0-20 cm),n(20-40 cm)and n(40-60 cm).Above results reflected that the greater the depth of sediment was,the better the adsorption performance was;The desorption ratio of three different depth sediments in ascending order was n(0-20 cm),n(20-40 cm) and n(40-60 cm),which reflected that the greater the depth of sediment was,the bigger the degree of desorption for ammonia nitrogen was;4) About magnitude relation of the ammonia nitrogen mass concentration between sediments' adsorption/desorption critical state and overlying water body,Tugou section's at 0-40 cm depth was greater;Yulin Village and Hehe Station sections' at 0-60 cm depth were less than overlying water body. Dynamic balance for ammonia nitrogen existed in the sediments' adsorption/desorption processes.This study provided theoretical guidance for dredging river management. |
| Key words: urban river sediment ammonia nitrogen adsorption desorption depth of sediment |
