Adsorption/desorption characteristics of sulfadiazine on the rhizospheric soils
磺胺嘧啶在作物根际土壤中的吸附/解吸特性研究

Rhizospheric soils incubated by rhizospheric bags were used to investigate the adsorption and desorption of sulfadiazine by soils under different rhizosphere effects. The studies showed that the adsorption and desorption of sulfadiazine by the test soils was very rapid. Elovich equation was the optimal model to describe the adsorption of sulfadiazine, followed by two-constant equation and parabolic equation, whereas parabolic diffusion equations were not suitable. The adsorption of sulfadiazine by these test soils increased with the increasing concentration of sulfadiazine within the range of sulfadiazine concentrations used in the experiment, but the amount of sulfadiazine adsorbed and fixed on rhizospheric soils was much higher than that on non-rhizospheric soils. The adsorption of sulfadiazine by the soils could fit well with the Freundlich equation, while Langmuir equation was not applicable to describe the isothermal adsorption processes of sulfadiazine by the test soils. The desorption processes of sulfadiazine on the test soils was non-linear. The desorption ability of rhizospheric soils was lower than that in non-rhizospheric soils. In addition, the relationship between average adsorption constants (Kf-ads) and average desorption constant (Kf-des) and the content of soil organic matter, pH, and sticky grain content showed that soil organic matter is the key factors affecting adsorption/desorption behaviors of sulfadiazine in root-soil interface.