Isotopic labelling for sensitive detection of nanoparticle uptake and translocation in plants from hydroponic medium and soil

Nath J., Dror I., Landa P., Moťková K., Vaněk T., Berkowitz B.

Keywords: copper nanoparticles, hydroponic cultivation, isotopically labelled nanoparticles, silver nanoparticles, zinc oxide nanoparticles
Abstract: Unintended releases of nanoparticles (NPs) into agricultural soil have recently raised concerns regarding NP accumulation in plants. In this study, specially synthesised isotopically labelled 107Ag-NPs, 65Cu-NPs and 70ZnO-NPs were exposed to three representative plants (Arabidopsis thaliana, Solanum lycopersicum (tomato) and Phragmites australis (common reed)) in hydroponic cultivation and, separately, to tomato plants cultivated in soil at concentrations of 2 mg L1. Metal concentrations in all samples were analysed byinductively coupled plasma mass spectrometry following acid digestion.The useofisotopically labelledNPs confirmedthatelevatedlevels ofmetalswere fromthe NPsourceused for the experiments. Although the highest concentrations of NPs or metals were detected in roots in both hydroponic and soil cultivations, varied levels oftranslocation to shootswere observed in different plants under hydroponic cultivation. In soil cultivation, where tomato plants were grown to full maturity, low levels of 107Ag (0.38 mg kg1) with respect to controlswererecordedintomatofruits; 70Znshowedthehighestleveloftranslocationtotomatostems(2.72mgkg1)and leaves (13.93 mg kg1). Furthermore, the amounts of NPs retained in the soil (at different depths) after harvesting tomato plants were also determined; the highest concentrations of respective isotopes (1.25 mg kg1 of 107Ag, 0.79 mg kg1 of 65Cu, 4.06 mg kg1 of 70Zn) were found in the top soil layer (,3 cm). Analysis of NPs exposed to plants in hydroponic medium indicated that the presence of plants increases the dissolution of NPs. Scanning electron microscopy analysis enabled determination of the location of 107Ag-NPs in the roots of tomato plants grown in soil; these NPs were found to accumulate mainly in the cortical cells.
DOI: 10.1071/EN19064
IEB authors: Přemysl Landa, Kateřina Moťková, Tomáš Vaněk