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土壤中氨氮与典型抗生素的吸附-解吸相互作用特征研究

Adsorption–Desorption Interaction Characteristics of Ammonium Nitrogen and Typical Antibiotics in Soil

  • 摘要: 在土壤和水体中,以氮为代表的传统污染物和以抗生素为典型的新污染物被普遍检出并呈现出复合污染特征,且伴随入渗过程在土壤和地下水中运移,同时受到其在土壤中吸附-解吸行为的影响。考虑到已有研究多聚焦于单一的氮或抗生素在土壤中吸附-解吸的局限性,本文通过批平衡实验方法分析了氨氮(\mathrmNH_4^+ -N)与两种典型抗生素环丙沙星(Ciprofloxacin,CIP)和泰乐菌素(Tylosin,TYL)在土壤中的吸附-解吸特性及其相互作用,探究氮和抗生素在土壤中的共迁移规律。通过Langmuir、Freundlich、linear三种热力学模型对等温吸附实验结果进行拟合,结果表明:Langmuir模型(R2>0.99)较Freundlich和linear模型更适用于描述\mathrmNH_4^+ -N的吸附特征,CIP浓度的增加会抑制土壤中\mathrmNH_4^+ -N的吸附,而TYL浓度的变化对\mathrmNH_4^+ -N在土壤中的吸附未呈现显著影响;CIP和TYL的吸附则更符合Freundlich模型(R2>0.99),\mathrmNH_4^+ -N浓度上升会抑制CIP的吸附,而\mathrmNH_4^+ -N对TYL的吸附存在低浓度促进高浓度抑制。采用解吸滞后系数(HI)表征解吸过程中吸附质在吸附剂中的不可逆程度,其中\mathrmNH_4^+ -N的HI值为0.370~2.306,但CIP和TYL的HI值均小于0.7,解吸滞后现象明显,说明CIP和TYL更容易持久性残留在土壤。本研究揭示了土壤中\mathrmNH_4^+ -N与CIP和TYL之间吸附-解吸相互作用规律,为进一步深入探索土壤中氮和抗生素的环境行为提供了基础数据支撑。

     

    Abstract: Conventional pollutants like nitrogen and emerging contaminants such as antibiotics are widely detected in soil and water, and exhibit combined pollution characteristics. Meanwhile, nitrogen and antibiotics migrate together during infiltration and are influenced by adsorption–desorption behaviors in soil. However, existing studies have mainly focused on the adsorption–desorption behaviors of single nitrogen or antibiotics, with fewer studies focused on the adsorption–desorption interactions between nitrogen and antibiotics. To address this gap, the adsorption–desorption dynamics of NH4+-N coexisting with two antibiotics—ciprofloxacin (CIP) and tylosin (TYL)—were investigated by batch equilibrium experiments in this study. The isothermal adsorption data were simulated by Langmuir, Freundlich, and linear models, with the Langmuir model (R2>0.99) being more suitable than the Freundlich and linear models to describe the adsorption of NH4+-N. The increase of CIP concentration inhibited the adsorption of NH4+-N, but no significant influence was observed on the adsorption of NH4+-N with the increasing of TYL concentration. The isothermal adsorption characteristics of CIP and TYL were a better fit for the Freundlich model (R2>0.99). The increase of NH4+-N concentration inhibited the adsorption of CIP, whereas adsorption of TYL was promoted by lower NH4+-N concentration but inhibited at higher concentration. The hysteresis index (HI) reflects the irreversibility of adsorbate retention on adsorbents during desorption. After calculating the HI of NH4+-N, CIP and TYL, it was found that NH4+-N exhibited an HI range of 0.370–2.306, whereas the HI values of both CIP and TYL were below 0.7, indicating significant desorption hysteresis. This suggests that CIP and TYL are prone to remain in soil and form persistent residues. The results of this study revealed the adsorption–desorption interaction characteristics between NH4+-N, CIP, and TYL, providing fundamental data to further understanding the environmental behaviors of nitrogen and antibiotics in soil. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202503290065.

     

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