[Hysteretic characteristics of atrazine desorption from fluvo-aquic soil].
Kinetic batch experiments are carried out in order to investigate the effects of a wide range of atrazine initial concentrations and consecutive desorption time on the desorption characteristics of atrazine from fluvo-aquic soil. The results reveal that, atrazine concentrations in soil solution gradually decreased with desorption time increasing, whose relationship can be expressed with empirically exponential functions. After consecutive five steps (or 5 days), when atrazine initial concentrations increased from 50 microg x L(-1) to 2000 microg x L(-1), the average desorption percentages were 23.1%, 30.4%, 33.0%, 36.4% and 38.5%, respectively. The relationships between the amount of atrazine adsorbed by soil colloids and corresponding atrazine concentrations in soil solutions may be described through the traditional and time-dependent desorption isotherms. The obvious discrepancies in two families of both traditional and time-dependent desorption isotherms from adsorption isotherm, which retention time last for 168 hours before commencement of desorption, were indicative of hysteresis. Two sets of Freundlich parameters derived from both desorption isotherms can quantify the hysteresis between desorption and adsorption isotherms. However, hysteresis coefficient, omega, was applicable only for the traditional desorption isotherms, H and lamda applicable for both.
Deng
Jian-cai
JC
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China. soilchem@issas.ac.cn
Jiang
Xin
X
Wang
Fang
F
Lu
Xin
X
Yu
Gui-fen
GF
Yan
Dong-yun
DY
Bian
Yong-rong
YR
D000327:Adsorption; D001280:Atrazine / Q000737:chemistry*; D004784:Environmental Monitoring; D006540:Herbicides / Q000737:chemistry*; D010573:Pesticide Residues / Q000032:analysis; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D013997:Time Factors
D006540:Herbicides; D010573:Pesticide Residues; D012987:Soil; D012989:Soil Pollutants; D001280:Atrazine