摘要
兽药抗生素(Veterinary antibiotics,VAs)通过多种途径进入土壤,极易对土壤及地下水环境带来严重危害。探究VAs在土壤中的吸附过程,对于深入了解土壤环境中VAs的污染与防控具有重要意义。选取兽药泰乐菌素(Tylosin,TYL)为目标污染物,采用批平衡实验法探讨其在3种不同类型黄土(灰钙土、棕黄土和黄绵土)中的吸附/解吸特性以及关键环境因素(温度、初始浓度、pH、离子强度等)对TYL吸附持留的影响,并结合动力学、热力学模型探究其作用机制。结果表明:TYL在3种黄土中的吸附平衡时间均在120 min内,吸附动力学过程符合准二级动力学模型(R^(2)>0.995),吸附热力学过程可以用Freundlich等温吸附模型描述(R^(2)>0.985),表明黄土有机质疏水分配和阳离子交换作用对TYL的吸附过程起到关键作用,土壤黏粒含量和pH也有一定影响。此外,解吸实验结果显示,解吸滞后系数(HI)在0.270~0.573之间,且解吸量始终大于50%,表明TYL吸附的不可逆性较低,在土壤中表现出的滞后现象不明显,容易解吸,会对地下水环境造成潜在威胁。随TYL初始浓度的增加,其在3种黄土中的吸附平衡时间延长,吸附容量也随之增大。吸附体系为酸性时有助于土壤对TYL的吸附;吸附体系为碱性时,灰钙土、棕黄土和黄绵土由于静电引力减弱,导致其对TYL的吸附量分别由0.264、0.341、0.289 mg/g显著降至0.105、0.077、0.078 mg/g。相对于K^(+)、NH_(4)^(+),高价态离子(如Ca^(2+)、Mg^(2+))及浓度较高离子的存在对TYL的吸附有明显抑制作用。研究显示,黄土对TYL的吸附主要与土壤有机质含量和阳离子交换容量有关,其主要吸附机制是阳离子交换作用和疏水作用。
Veterinary antibiotics(VAs)enter the soil through various pathways and can pose serious threats to the soil and groundwater environment.Studying the adsorption process of VAs in soil is crucial for a comprehensive understanding of the pollution and control of VAs in the soil environment.This study selects tylosin(TYL)as the target pollutant and uses batch equilibrium experiments to examine its adsorption/desorption behaviors on three types of loess(sierozem,brow-yellow soil and cultivated loess).Key environmental factors such as temperature,initial concentration,pH,and ionic strength were studied.Dynamic and thermodynamic models were utilized to elucidate the underlying mechanisms.The results indicated that the adsorption equilibrium time for TYL on all three soils was within 120 minutes.The adsorption kinetics followed the pseudo-second-order model(R^(2)>0.995),and the thermodynamics were described by the Freundlich model(R^(2)>0.985).Soil organic matter and cation exchange capacity were identified as key factors in the adsorption process,with soil clay content and pH also playing a role.Additionally,desorption experiments revealed that the desorption hysteresis coefficient(HI)ranged from 0.270 to 0.573,and the desorption amount always exceeded 50%.This indicates that TYL has low irreversibility of adsorption,shows no apparent hysteresis in soil,and is easy to desorb,potentially posing a threat to the groundwater environment.Furthermore,an increase in the initial concentration of TYL resulted in longer equilibrium time and higher adsorption capacity.When the adsorption system was acidic,the adsorption of TYL in soil was promoted.However,under alkaline conditions,the adsorption capacity of TYL on the three types of loess soils decreased significantly from 0.264,0.341 and 0.289 mg/g to 0.105,0.077 and 0.078 mg/g,respectively,due to the weakening of electrostatic attraction.Compared with K^(+)and NH_(4)^(+),the presence of high-valent ions such as Ca^(2+),Mg^(2+)and ions with high concentration had a significant inhibitory effect on the adsorption of TYL.The results revealed that the adsorption of TYL by loess was mainly affected by soil organic matter content and cation exchange capacity,with cation exchange and hydrophobic interactions being the main adsorption mechanisms.These research results provide important scientific evidence for assessing the behavior and fate of typical VAs in the soil environment.
作者
刘哲炜
蒋煜峰
何蕊
吴嘉丽
张晓珍
刁静茹
吴应琴
LIU Zhewei;JIANG Yufeng;HE Rui;WU Jiali;ZHANG Xiaozhen;DIAO Jingru;WU Yingqin(School of Environmental&Municipal Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;Key Laboratory of Petroleum Resources Research,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China)
出处
《环境科学研究》
CAS
CSCD
北大核心
2024年第9期2006-2019,共14页
Research of Environmental Sciences
基金
国家自然科学基金项目(No.21966020)
甘肃省自然科学基金项目(No.20JR5RA392)。
关键词
泰乐菌素
黄土
吸附持留
影响因素
tylosin
loess
adsorption and retention capacity
influencing factors
