Concentration of Trace Metals in Willow (Salix spp. ) Leaves

Abstract

The title method was used for phytoremediation of soils. The experiments were performed with leaves of willow (S. smithiana, S. alba,S. rubens and S. dasyclados) grown in soil contaminated with heavy metals (Cd, Zn, Pb), The ability of the leaves to accumulate these metals was confirmed. The total contents of metals in 0.02 mol l⁻¹ Tris buffer (pH 7.5) and in 1 mol l⁻¹ sodium hydroxide extracts were determined. Size exclusion chromatography combined with inductively coupled plasma mass spectrometry was used for separation and determination of metals in the extracts. The metals in the extracts are present mainly in low-molecular-weight fractions (M ? 2 kDa). These fractions were obtained by preparative size exclusion chromatography and refined by immobilized metal affinity chromatography. The compounds in the fractions were analyzed by amino acid analysis and MALDI mass spectrometry. The results show that majority of heavy metals in willow biomass remained in insoluble residue whereas the extracts contain substantial amounts of chelating agents, which suggests their role in metal detoxication processes in willow plants.