Soil properties influence the response of terrestrial plants to metallic nanoparticles exposure

Metal-based nanoparticles such as Ag, ZnO, CuO, TiO2, and others possess unique properties that lend them to a wide array of uses. This means that during manufacture, use, or upon disuse, these nanoparticles can become constituents of the soil. Upon interaction with soil, nanoparticles affect soil processes, and in turn are affected by soil properties. The soil factors affecting nanoparticles can be classified into chemical (e.g., pH, organic matter, and ionic strength) and biological (e.g., plant root exudates, microbes, and microbial activities). Some well-known fates of nanoparticles in soil include aggregation of individual nanoparticles (homoaggregation) or of nanoparticles with other soil constituents (heteroaggregation); dissolution to ionic species and, potentially, sorption of the ions onto organic matter or precipitation with chloride; acquisition of surface coating; change in surface charge; and change in shape. These modifications alter nanoparticles reactivity, which diminishes or enhances their bioactivity in plant systems. Thus, the degree to which nanoparticles influence plants depends to a large extent on the complexity of soil property.