Microbial release and degradation of nonextractable anilazine residues

Humic substance fractions obtained from a degraded loess soil taken from a long-term lysimeter experiment with the fungicide anilazine were incubated in aerated liquid cultures together with native soil microorganisms. Biomin eralization, remobilization of [U-phenyl-C-14]anilazine, respectively, its metabolites, and changes of the humic matrix were observed under variable n utrient conditions. Stimulated microbial activity favored the degradation o f nonextractable C-14-anilazine residues. However, nitrogen deficiency enha nced structural changes in the humic substances, which seemed to be used th en as a nitrogen source. Along with the microbial degradation of the humic substance, parts of the bound anilazine residues became remobilized. Furthe rmore with the use of AMD-TLC, dihydroxy anilazine was detected within the nonextractable residues. The portion of rather weak bondings between the so il organic acids and the anilazine residues turned out to be considerably l ower in the humic acids fractions than in the fulvic acids fraction.