The first evidence of accumulation and avoidance behavior of macroinvertebrates in a forest soil spiked with human-made iron nanoparticles: A field experiment.

Both earthworms and terrestrial isopods have been used to evaluate the quality of contaminated soil by NPs. However, most experiments have been conducted in the laboratory and under greenhouse conditions. Besides, little is known of Fe accumulation in earthworms from iron NPs (Fe NPs) under natural conditions. Therefore, the objective of this research was to evaluate the effect of manufactured NPs on the accumulation of Fe in macroinvertebrates from forest soil. Our results revealed that earthworms consume low amounts of Fe in a concentration of 1000 mg Fe NPs kg of dry soil, with a behavior constant over time. Besides, we observed that earthworms could not detect Fe at low concentrations (1 or 10 mg Fe NPs kg), so they do not limit soil consumption, which translates into high amounts of Fe in their bodies. By contrast, the content of Fe in organisms is inversely proportional to increasing concentrations in the soil (R = -0.41, < 0.05). Therefore, although studies are needed, in addition to considering environmental factors and the physicochemical properties of the soil, endogenous worms in the evaluated area could, under natural conditions, be useful to inform us of contamination of NP manufactured from Faith. Besides, for future research, a novel methodology should be considered to demonstrate more realistic avoidance behavior under field conditions.