Characterization of personal exposure concentration of fine particles for adults
and children exposed to high ambient concentrations in Beijing, China |
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Authors: | Xuan Du Qian Kong Weihua Ge Shaojun Zhang and Lixin Fu |
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Institution: | 1. Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China 2. Xi'an Municipal Engineering Design and Research Institute Co., Ltd, Xi'an 710068, China |
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Abstract: | 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. |
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Keywords: | personal exposure PM2 5 high ambient concentration |
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