Copper accumulation in the aquatic fern Salvinia minima causes more severe physiological stress than zinc.

Copper (Cu) and zinc (Zn) have a high demand in the industry. However, these ions, at high concentrations, can cause severe damage to both fauna and flora. Phytoremediation has gained international importance because its relatively low cost and it is environmentally friendly. The aim of the present study was to evaluate the capacity of Salvinia minima of accumulating Cu and Zn from aqueous solutions of various external concentrations (20, 40 and 80 µmol L-1 of CuSO4 and ZnSO4, separately). In addition, to estimate the effect of exposure of S. minima plants to those metals, on various physiological parameters (growth potential, maximum quantum efficiency of PSII, electrolyte leakage: as a cell membrane integrity index). S. minima was able of accumulating more Zn than Cu in its tissues, reaching values of 6.96 mg Cu g-1 dry weight (DW) and 19.6 mg Zn g-1 DW when exposed to 80 µM of each metal during 96 h, that were stored mainly at roots. Despite accumulating less Cu in its tissues, Cu had more severe reductions in various physiological parameters than Zn (in maximum quantum efficiency, integrity of cell membranes, and growth). We conclude that this species can be useful in the phytoremediation for copper and zinc in relatively short time, as maximum accumulation occurred within the first 24 h. However, in the long term, the accumulation of such metals is accompanied by a negative impact in the appearance, physiology, and growth of this plant species, which was more severe for copper exposure than for zinc.