Sorption and mobility behavior of carpropamid in soil

Author： Shabeer T.P. Ahammed Gupta Suman

ISSN： 0277-2248

Source： Toxicological and Environmental Chemistry, Vol.93, Iss.2, 2011-02, pp. : 215-222

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Abstract

Adsorption-desorption and leaching behavior of 2,2-dichloro-N-(1-(4-chlorophenyl) ethyl)-1-ethyl-3-methylcyclopropane carboxamide (carpropamid), a rice blast fungicide, was studied under laboratory conditions in rice field soil using a batch equilibration technique in 0.01 mol L-1 CaCl2 solution in the concentration range 0.01-2.0 mg L-1. The adsorption isotherm was observed to be of 'S' type. The value of Kads = 22 revealed that soil has high capacity of adsorption, whereas nads = 0.74 showed strongly nonlinear adsorption. About 22-26% of the adsorbed carpropamid was desorbed in four desorption cycles. The hysteresis coefficient varied from 9.4 to 11.8 for different concentrations, indicating slow desorption. Leaching studies were carried out in duplicates in packed soil columns under saturated flow conditions. Columns were leached with water equivalent to ∼50-400 mm of rainfall. No residues of carpropamid were detected in leachate in any of the treatments and were detected only up to 10 cm depth in the soil. In all the treatments, more than 95% of the recovered amount was present in the top 5 cm. The leaching behavior of carpropamid with formulation treatment (300 suspension concentrate) was found to be similar to technical material.