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Modeling the Influence of Sorption and Transformation on Pesticide Leaching and Persistence
Author(s) -
Boesten J. J. T. I.,
Linden A. M. A.
Publication year - 1991
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1991.00472425002000020015x
Subject(s) - leaching (pedology) , sorption , pesticide , environmental science , soil science , persistence (discontinuity) , environmental chemistry , chemistry , soil water , environmental engineering , agronomy , geology , adsorption , geotechnical engineering , organic chemistry , biology
Pesticide leaching to ground water at 1 m depth and pesticide persistence in the plow layer were calculated with a mathematical model for a sandy soil continuously cropped with maize ( Zea mays L.) and exposed to weather conditions in a temperate climate. The pesticide was applied in spring. In the model, water flow was described by Darcy's law and water uptake by the crop was included. Dally averages of meteorological conditions (rainfall, evapotranspiration, soil temperature) were used as input. The model assumes first‐order transformation, equilibrium sorption (Freundlich equation), and passive plant uptake. Pesticide leaching and persistence were calculated as a function of pesticide sorption (characterized by the organic‐matter/water distribution coefficient, K om ) and of transformation rate. It was found that pesticide leaching is very sensitive to both K om and the transformation rate: changing K om or the transformation rate by a factor of 2 changes the fraction of the dose leached typically by about a factor of 10. Pesticide persistence in the plow layer was found to be sensitive to K om at low transformation rates and sensitive to the transformation rate at high K om values. Additional calculations showed that autumn application results in much higher leaching of nonsorbing pesticides with short half‐lives than spring application (difference of two orders of magnitude).