环丙沙星在热带土壤中的吸附—解吸特征研究

摘要

研究了氟喹诺酮类抗生素的代表性药物环丙沙星在典型热带土壤中的吸附-解吸特征,以期揭示其在热带土壤中的吸附机制.结果表明,环丙沙星在3种热带土壤中的等温吸附、解吸行为均能用Freundlich方程和Langmuir方程较好的拟合,且其在土壤中的吸附属于物理吸附；不同土样中环丙沙星的解吸强度明显高于吸附强度,其中水稻土对环丙沙星的吸附能力最强,其次为砖红壤、燥红土,而环丙沙星在砖红壤中的解吸能力最强,其次为水稻土、燥红土；环丙沙星在3种热带土壤上的吸附容量、吸附强度、最大吸附量存在很大的差异,这可能与土壤的有机质、粘粒含量,以及pH有关；环丙沙星在3种热带土壤上的解吸过程存在明显的滞后现象,且不同土壤中的解吸滞后系数变化存在明显差异,其中砖红壤的解吸滞后现象明显高于(p＜0.01)其他2种土壤；由于环丙沙星在土壤中强烈的解吸滞后性,预示其可能存在较大的潜在环境风险.%Batch adsorption equilibrium experiments of a typical fluoroquinolone antibiotic, ciprofloxacin, on three tropical soils were carried out base on the OECD guideline 106. The adsorption and desorption characteristics was investigated to reveal the mechanism of ciprofloxacin adsorption. The isotherm adsorption and desorption behaviors of ciprofloxacin on three tropical soils could be better described by both Freundlich and Langmuir model. The adsorption process belonged to the physical type, and the desorption intensity of ciprofloxacin significantly higher than the adsorption intensity. The maximum adsorption capacity of ciprofloxacin was found on paddy soils, which was followed by Latosols and Torrid red soils, while the desorption capacity of three tropical soils was in order of Latosols> paddy soils>Torrid red soils. There were big differences found among the ciprofloxacin adsorption behavior on three tropical soils, including the adsorption capacity, intensity and maximum adsorption capacity, this might be related to the content of organic matter and clay in soil or soil pH. An apparent desorption hysteresis was found in the desorption process of three tropical soils, especially on Latosols for its higher hysteresis index (p<.0. 01). Because of the intense desorption hysteresis of ciprofloxacin, it might had big potential environmental risk.