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Description of Simazine Transport with Rate‐Limited, Two‐Stage, Linear and Nonlinear Sorption
Author(s) -
Streck Thilo,
Poletika Nicholas,
Jury William A.,
Farmer Walter J.
Publication year - 1995
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/94wr02822
Subject(s) - sorption , simazine , lysimeter , desorption , tracer , chemistry , environmental science , nonlinear system , adsorption , environmental chemistry , thermodynamics , soil science , physics , soil water , pesticide , organic chemistry , nuclear physics , atrazine , agronomy , biology , quantum mechanics
This study was conducted to reconcile an apparent inconsistency between the simazine laboratory sorption isotherm data and the field lysimeter transport experiment reported by Poletika et al. (this issue). In this investigation, linear and nonlinear one‐ and two‐stage simazine sorption models were fitted to the sorption and desorption isotherm laboratory data to obtain parameter estimates for use in the transport model. Once obtained, the calibrated sorption model was combined with the parameterized outflow concentration record from a mobile Br tracer to represent rate‐limited sorption and transport of the simazine added simultaneously with the Br. The calibrated model did an excellent job of representing the final simazine profile in the soil, particularly with the nonlinear model. This is in contrast to a single‐stage adsorption model tested by Poletika et al. (this issue), which reached poor agreement with the field profile when laboratory‐measured sorption parameters were used. The results demonstrate the compatibility of field and laboratory experiments on pesticide movement and also indicate that sorption isotherms may require substantially longer to reach equilibrium than is customarily allowed in current protocols.