InfluÃncia da polaridade de pesticidas nÃo-iÃnicos sobre sua sorÃÃo em um latossolo. / Influence of the polarity of non-ionic pesticides on theirs sorption by a Latosol.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The sorption of thirteen non-ionic pesticides, with varying n-octanol/water partition coefficients (Kow), by soil material taken from the A horizon of an Acriferric Red Latosol was investigated. Sorption isotherms of the pesticides were determined by the shake-flask method. The amount of chemicals in aqueous solutions was measured by HPLC with UV detector. Sorption isotherms of all pesticides fitted well the Freundlich model, with sorption coefficient (Kf) values ranging from 0.2 to 202 mL.nmol-1. Log Kf values were shown to be linearly correlated (R2 = 0.87) with the log Kow values of the pesticides, revealing that hydrophobic partitioning onto organic matter was the dominant mechanism of their sorption by the studied soil; however, given that the sorption coefficients were not precisely reflected by the partition of the compounds between n-octanol and water, the results indicated that other factors affect the sorption of non-ionic pesticides in soils. For many compounds, the observed Kf values were higher than those predicted by the Briggs (1981) equation, which relates the Kf of the pesticide to its Kow and to the content of organic matter in the soil. The results showed that the equation obtained for soils of England, is not adequate to predict the Kf values of pesticides for the studied soil in this work, and that qualitative aspects of soil organic matter may be an important factor affecting the sorption of non-ionic pesticides by soils.

ASSUNTO(S)

solo; sorÃÃo; pesticida; coeficiente de sorÃÃo agronomia soil; sorption; pesticides; sorption coefficient

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