Nuclear microprobe studies of elemental distribution in seeds of Biscutella laevigata L. from zinc wastes in Olkusz, Poland

Abstract

Biscutella laevigata L. ( Brassicaceae), a rare perennial metallophyte plant species known mainly from Central and Southern Europe, has a very restricted distribution in Poland. This investigation focuses on one known Polish lowland location of B. laevigata on zinc dumps near Olkusz, Upper Silesia. The results presented are a continuation of earlier studies, undertaken to understand mechanisms of plant adaptation to a hostile environment, rich in heavy metals. The analyses were performed with 3.0 MeV protons, using the National Accelerator Centre (NAC) nuclear microprobe. Two complementary techniques, proton-induced X-ray emission (PIXE) and proton backscattering spectrometry (BS), were simultaneously used. Quantitative elemental maps showed that seed tissue was defined by specific elemental allocation patterns. The highest concentration of Zn and other heavy metals was found in the endosperm. Within embryonic tissue, the highest amount of Zn was found in the radicle. Mapping artefacts, related to specimen shape, are discussed. The results show that plants strictly and actively select elements and their amounts taken up by different tissues. This mechanism is probably responsible for their survival.