Batch experiments were carried out to investigate the effects the desorption characteristics of atrazine from a sandy loam soil of initial atrazine concentrations and consecutive desorption steps on As initial atrazin...Batch experiments were carried out to investigate the effects the desorption characteristics of atrazine from a sandy loam soil of initial atrazine concentrations and consecutive desorption steps on As initial atrazine concentration increased, the average percentage of atrazine desorption on the sandy loam soil ranged gradually from 23.1% to 38.5% after five consecutive desorption steps. The values of the Freundlich capacity parameter, kdes, derived from the initial concentration and time-dependent desorption isotherm were consistently higher than those associated with sorption. The opposite trend was observed only for the values of nonlinear parameter, rides, from the initial concentration-dependent desorption isotherms. Atrazine hydrolysis to hydroxyatrazine and bound residue formation were mainly responsible for the observed hysteresis in its sorption and desorption isotherms. For the initial concentration-dependent desorption isotherms, as initial atrazine concentration increased, the values of hysteretic coefficients ω and λ decreased, and H values increased. However, the relationships between initial atrazine concentration and hysteretic coefficients were not pronounced for ω, H, or λ. For the time-dependent desorption isotherms, λ, and H values increased as the atrazine desorption step proceeded. The correlation between hysteretic coefficient and desorption step was highly significant for λ （P 〈 0.0001）, but not for H.展开更多
基金supported by the Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences(No. NIGLAS2010KXJ01)the National Natural Science Foundation of China(No. 40901252)the National Water Pollution Control and Remediation Key Endowment(No.2008ZX07101-012)
文摘Batch experiments were carried out to investigate the effects the desorption characteristics of atrazine from a sandy loam soil of initial atrazine concentrations and consecutive desorption steps on As initial atrazine concentration increased, the average percentage of atrazine desorption on the sandy loam soil ranged gradually from 23.1% to 38.5% after five consecutive desorption steps. The values of the Freundlich capacity parameter, kdes, derived from the initial concentration and time-dependent desorption isotherm were consistently higher than those associated with sorption. The opposite trend was observed only for the values of nonlinear parameter, rides, from the initial concentration-dependent desorption isotherms. Atrazine hydrolysis to hydroxyatrazine and bound residue formation were mainly responsible for the observed hysteresis in its sorption and desorption isotherms. For the initial concentration-dependent desorption isotherms, as initial atrazine concentration increased, the values of hysteretic coefficients ω and λ decreased, and H values increased. However, the relationships between initial atrazine concentration and hysteretic coefficients were not pronounced for ω, H, or λ. For the time-dependent desorption isotherms, λ, and H values increased as the atrazine desorption step proceeded. The correlation between hysteretic coefficient and desorption step was highly significant for λ （P 〈 0.0001）, but not for H.
