Fe3O4 nanoparticles permitted to substantially increase the resistance of the soil microbial biomass to the toxic impact of high and extremely high concentrations of trifluralin. The effect was maximal at the maximal concentrations of the pollutant in soil and consisted in significant increase of the microbial biomass and concomitant decrease of the basal respiration (fig. 1)figureFe3O4 nanoparticles were prepared according to the chemical co-precipitation method using iron(II) sulfate and iron(III) chloride in the presence of poly-N-vinylpyrrolidone (PVP). The resulting magnetite nanoparticles were characterized by X-ray powder diffraction (XRD) analysis and scanning electron microscopy (SEM).The nanoparticles were introduced into soil in the form of crystal powder in the concentration of 100 mg/kg.