| Abstract
| - The transformation of the herbicide bentazon in soil wasinvestigated with radiolabeled bentazon and its derivatives8-hydroxybentazon, 8-methoxybentazon, and N-methylbentazon. Mineralization of bentazon was a microbial activitywhich required the presence of oxygen and was impededby additional carbon substrates such as powderedalfalfa (Medicago sativa) residues. The formation of boundresidues of bentazon in humic substance depended onmicrobial activity, too, and was stimulated by the presenceof oxygen; however, there was also a significantimmobilization of bentazon in the absence of oxygen. Aculture of the fungus Phanerochaete chrysosporium converted8-hydroxybentazon to a dimeric derivative. The samedimer was formed by the action of laccase. This dimerand the monomeric 8-OH-bentazon acted as key metabolitesin the formation of bound residues from bentazon. Thefurther mineralization of bound bentazon residues was aslow process, with 9.3% mineralization within 141 d.
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