Quantifying hysteresis of atrazine desorption from a sandy loam soil
Jiancai Deng , Xin Jiang , Weiping Hu , Liuming Hu
DOI:
Received March 16, 2010,Revised June 07, 2010, Accepted , Available online
Volume 22,2010,Pages 1923-1929
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Batch experiments were carried out to investigate the e ects of initial atrazine concentrations and consecutive desorption steps on
the desorption characteristics of atrazine from a sandy loam soil. 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, ndes, 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 coe cients ! and decreased, and H values increased.
However, the relationships between initial atrazine concentration and hysteretic coe cients were not pronounced for !, H, or . For
the time-dependent desorption isotherms, and H values increased as the atrazine desorption step proceeded. The correlation between
hysteretic coe cient and desorption step was highly significant for (P < 0.0001), but not for H.
