V3 No2 390 399 2002 by pengtt

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									V3 No2 390 399 2002
Journal of Environmental Protection and Ecology

                                                                  Agricultural pollution

ADSORPTION-DESORPTION AND MOBILITY OF 14C-
ETHOFUMESATE IN MOROCCAN SOILS

A. SATRALLAHa, A. DAHCHOURa*, M. BADRAOUIa, E. ESSASSIb,
M. J. SANCHEZ-MARTINc
a
   Institut Agronomique et Veterinaire Hassan II. B. P. 6202 Rabat-Instituts,
Morocco
E-mail: adahchour@yahoo.fr
b
   Faculti des Sciences, Departement de Chimie, 1014 Ibn Batouta Avenue,
Rabat, Morocco
c
  Instituto de Recursos Naturales y Agrobiologia, CSIC, Cordel de Merinas
40-52, E-37071 Salamanca, Spain
Abstract. A study was made of the adsorption-desorption and mobility of the herbicide
ethofumesate (2-ethoxy-2,3-dihydro-3,3-dimethylbenzofuran-5-ylmethane sulfonate) in
fourteen agricultural soils from different areas of Morocco. Adsorption isotherms were
obtained using the batch equilibrium technique and mobility was studied using soil thin
layer chromatography. The adsorption and desorption isotherms fit the Freundlich
equation, the Kf values ranged between 0.61 and 4.73 and the nf values were always lower
than unity. The desorption isotherms display positive hysteresis in all soils and the
greatest hysteresis was seen in soil with the highest organic matter content. Adsorption
constants and distribution coefficients were found to be significantly correlated
(/?<0.01) with the organic matter content of the soils. According to the determination
coefficient, r2, organic matter would account for 60% of the variance in adsorption. On
the basis to the Rf values obtained, ethofumesate is slightly mobile in 28% and
moderately mobile in 72% of the soils studied. The results obtained indicate the
importance of the organic matter in the adsorption-desorption and mobility of
ethofumesate in the Moroccan soils studied.
Keywords: adsorption, desorption, mobility TLC, 14C-ethofumesate, Moroccan soils.

								
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