MicroPIXE analysis of removal of aqueous U(VI) by S. intermedia and P. stratiotes in the presence of Th(IV)

Abstract

In this work, Spirodela intermedia and Pistia stratiotes, autochthonous floating macrophytes, were used to remove aqueous UO22+ (1 and 10 mg.L−1) under laboratory conditions. The influence of Th4+(1 mg.L−1) was studied for the highest concentration of U(VI). All the parameters of the bioremediation process, bioconcentration factors (BCFs) in roots and leaves and translocation factors (TFs), were achieved by microPIXE quantification. This analysis was carried out using a 50-MeV 16O5+ beam with the aid of the heavy-ion microprobe at the TANDAR Laboratory in Buenos Aires. High resolution 2D maps of the in vivo elemental distribution in macrophytes for different conditions were obtained. Both plants have the ability to accumulate a large amount of U(VI) yielding BCFs > 500. Only S. intermedia can additionally uptake Th(IV) reaching a high BCF (>300 at 96 h) but the plant does not survive; Th was detected within the chlorenchyma ([Th] ≅ 30 µg.g−1).