septiembre 2018

Contribution to the study of the dynamics of heterocyclic nitrogenated herbicides in soils treated with copper salts

Moreno, M.T., Rodríguez-Amaro, R., Rodríguez-Mellado, J.M., Mayén, M., Jiménez-Guardeño, F.

Accede

Abstract

The interaction between the Cu(II) ions and heterocyclic herbicides (triazines and imidazolinones) is studied by electrochemical and spectrophotometric measurements in relation to the environmental consequences of this interaction. The formation of very stable complexes between the herbicides and the metal ions is assessed. Due to the occurrence of acid–base reactions, the stability constants of the complexes were obtained at three pH values for the imidazolinone herbicides and at only in neutral media for triazine herbicides. Imidazolinones form 1:1 complexes in strongly acidic media and 1:2 complexes (one copper ion and two herbicide molecules) in the rest of pH values studied. Triazine herbicides form 1:2 complexes. The complexes formed in the pH range 5–10 (that is, the pH of most soils) are more stable for triazines than for imidazolinones, though in both cases this complex formation increases the low solubilities of the herbicides in water. This can lead to a decrease in the persistence of the herbicides and an increase in the ability of both the herbicides and the Cu(II) ions to reach groundwater and, consequently, to unwanted areas of crops.

Copper complexes Heavy metals pollution Imidazolinone herbicides Pyridine herbicides Stability constants