Uptake, translocation, weathering and speciation of gold nanoparticles in potato, radish, carrot and lettuce crops

Highlights: • Au-NP uptake and translocation following soil application differ among plants. • Au-NP dissolution and Au-NP size changes are determined in different (dried) plant parts. • Plants can break down NPs prior to uptake in the rhizosphere. • Plants can reorganize ionic metals as NPs in their tissues. • Fully-grown plants show elevated uptake and translocation. Extensive use of nanomaterials in agriculture will inevitably lead to their release to the environment in significant loads. Thus, understanding the fate of nanoparticles in the soil-plant environment, and potential presence and consequent implication of nanoparticles in food and feed products, is required. We study plant uptake of gold nanoparticles from soil, and their distribution, translocation and speciation (in terms of particle size change and release of ionic Au) in the different plant tissues of four important crops (potato, radish, carrot and lettuce). Our new analytical protocol and experiments show the feasibility of determining the presence, concentration and distribution of nanoparticles in different plant parts, which differ from plant to plant. Critically, we identify the evident capacity of plants to break down (or substantially change the properties of) nanoparticles in the rhizosphere prior to uptake, as well as the evident capacity of plants to reorganize ionic metals as nanoparticles in their tissues. This could lead to nanoparticle exposure through consumption of crops.