Macroscopic assessment of nanosilver toxicity to soil denitrification kinetics

A large increase in commercial and home use of silver nanoparticle (AgNP) products and technologies has raised concerns about their impact on environmental health. While several sources cite soils and sediments as the predominant sink for AgNPs in natural environments, few studies contribute to risk assessment of AgNPs in terrestrial environments. In this study, the effect of AgNPs ([Ag]: 1-100 mg/kg, 15-50 nm with 0-90% polyvinylpyrrolidone [PVP] capping agent) on soil denitrification processes was investigated with batch kinetic experiments using well-characterized AgNPs. Although the effects on denitrification kinetics and equilibrium end-points were variable among the AgNPs, denitrification kinetics were limited under certain conditions (e.g., PVP-coated AgNPs ≥ 10 mg/kg). In assessing the impact of AgNPs on ecosystem processes, it is important to consider the interactions of AgNPs with soils and sediments in addition to the physicochemical properties (size, coating agents, sedimentation rate, solubility, surface charge properties, dispersibility) of AgNPs.