Estimating the Toxicity and Biological Availability for Interaction Products of Metallic Iron and Humic Substances

This article considers the influence that suspensions of nanoparticles (sized from 10 to 60 nm) of iron oxo-compounds in different oxidation states have on biological objects. The suspension is formed by the interaction of metallic iron with aqueous solutions of humic substances. Based on the example of green microalgae Scenedesmus quadricauda (Turp.) Breb., it is shown that suspensions that contain iron oxo-compound nanoparticles stabilized with humic substances at an iron concentration from 0.14 to 2036 µM do not have a toxic effect on microalgae. The availability of iron contained in the suspensions was evaluated in the experiment on sprouts of wheat Triticum aestivum L., which had been grown under iron-deficient conditions. The root uptake of the ionic form of iron contained in the suspension was confirmed. It is shown that the studied suspensions of iron nanoparticles stabilized by humic substances accumulate on the surface of plant roots. These suspensions are supposed to be a source of iron with prolonged action for plants.