BIOSTIMULATION OF AGRICULTURAL BIOBEDS WITH NPK FERTILIZER ON CHLORPYRIFOS DEGRADATION TO AVOID SOIL AND WATER CONTAMINATION
Degradation of the insecticide chlorpynfos (160 a.i mg kg-1) using a biomix of a biobed system biostimulated with inorganic fertilizer (NPK) was investigated. Three concentrations of the fertilizer (0.1%, 0.5% and 1.0% ww-1) were evaluated on chlorpynfos degradation, TCP (3, 5, 6-trichloro-2-pyrinidol) accumulation and biological activity of the biomix. The chlorpynfos was dissipated efficiently (>75%) after 40 days of incubation and no additional dissipation was obtained with increasing concentration of NPK after 20 days of incubation. TCP accumulation occuned in all evaluated NPK concentrations and its concentration increased with the increment of NPK addition raising the probability of leaching of this compound. Biological activity (FDA and ligninolytic enzyme activity) in the biomix increased by the NPK presence in all evaluated concentrations. The DGGE analyses showed that combined treatments with lower amounts of NPK (0% and 0.1%) and chlorpynfos showed no significant modifications in the microbial community in the biomix. However, combined overdoses of NPK (0.5 and 1.0%) and chlorpynfos caused significant modifications in the bacterial communities that could be associated with TCP degradation reduction in the biomix. In conclusion, the obtained results demonstrated that the biomix prepared with Andisol and biostimulated with NPK nutrient can be recommended in biobeds as a viable alternative of chlorpyrifos dissipation avoiding soil and water contamination probability.