Adsorption-desorption study of bromophos methyl and quinalphos in Greek soils

Abstract

The adsorption and desorption of bromophos methyl [O, O-dimethyl–O-(2, 5-dichloro-4 bromophenyl) phosphorothioate] and quinalphos [O, O-diethyl O-2-quinoxalinyl phosphorothioate] on five soils from different Greek locations with varying physical and chemical properties was studied by batch equilibration method. Adsorption isotherms fitted well to the Freundlich equation. The adsorption capacity of the soils for bromophos methyl was higher than quinalphos. Freundlich adsorption coefficient (K_fads ), showed significant correlation with soil organic matter, indicating that soil organic matter content was the main controlling factor for the adsorption of these pesticides on the soils. Desorption isotherms also conformed well to the Freundlich equation and there was a hysteresis effect in all the soils. The Freundlich K_fdes values were also higher for the soils with the highest organic matter per cent.

Keywords:

• bromophos methyl
• quinalphos
• per cent balance
• organic matter
• adsorption

Acknowledgements

We would like to thank Mr M. Tzoumelekas Miltos from the National Agricultural Research Foundation (N.AG.REF) for soil analysis. Md. Azharul Islam acknowledges financial support from IKY (Greek State Scholarships Foundation). Comments and valuable suggestions from the reviewers are also gratefully acknowledged.