Synchrotron Micro-X-Ray Fluorescence Elemental Imaging Reveals Zinc Distribution in the Hyperaccumulator Sedum plumbizincicola (Crassulaceae)

Abstract

Sedum plumbizincicola is a zinc–cadmium (Zn–Cd) hyperaccumulator native to China with high potential for use in the phytore-mediation of contaminated soils in temperate climates. This study aimed to determine the Zn accumulation and distribution in S.plumbizincicola tissues grown on soils co-contaminated with Cd, Pb, and Zn. The efficiency of Zn accumulation was assessed inmonoculture and intercropping systems with Noccaea caerulescens. The samples were analyzed by inductively coupled plasma–atomic emission spectrometry and synchrotron micro-X-ray fluorescence elemental imaging. Sedum plumbizincicola grown inmonoculture had significantly higher foliar Zn concentrations than the plants grown with N. caerulescens, with the leaf tips,petioles and nodes being the main sites of Zn localization in the aerial parts. The highest Zn concentrations were observed inthe epidermis and vascular system of both leaves and stems, with the distribution pattern differing between young and matureleaves. This study highlights the Zn localization patterns in S. plumbizincicola to improve our understanding of the underlyingmechanisms of Zn hyperaccumulation. Growing in monoculture, S. plumbizincicola is an effective candidate for Zn agrominingor phytoremediation of Zn- Cd contaminated soils, with less promising results when intercropped with N. caerulescen