Accumulation and distribution of zinc within Miscanthus × giganteus plants grown on elevated Zn concentrations and their photosynthetic performance were investigated. High concentrations of Zn in soils caused an increase of its concentrations in all plant organs. The bioconcentration factor, bioaccumulation factor, and translocation factor were lower than one indicating that M. × giganteus is an excluder plant species. Excessive Zn induced visible leaf damage, i.e. chlorosis and necrosis, only in the oldest leaves, pointing to Zn accumulation. Elevated amounts of Zn in leaves significantly lowered the photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO 2 concentrations, parameters of chlorophyll a fluorescence, and chlorophyll b content. Despite Zn excess in leaves, there was no severe reduction in the maximal quantum yield of PSII photochemistry, indicating a high photosynthetic capacity, high tolerance to elevated Zn concetrations, and ability of M. × giganteus to grow on Zn-contaminated soils.

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Heavy metal contamination of aquatic ecosystems directly threatens the health, production and biodiversity of aquatic and surrounding terrestrial ecosystems, and it represents a serious global problem. Metal extraction during ore processing produces large amounts of wastes that remain in tailings at the mining site. Fine waste particles represent a long-term source of potentially toxic metals that can be released into the ground and surface water as a result of their progressive chemical weathering. Aquatic macrophythes have a major role in absorption and accumulation of heavy metals and thereby in natural water purification. The presence of naturally growing plants on mine tailing ponds indicates their tolerance of heavy metal pollution and suggests a possible role for them in phytoremediation. In the present study, we analysed the concentrations of heavy metals (Fe, Mn, Ni, Zn, Pb, Cd, Co, Cu) in Phragmites australis plants growing spontaneously in shallow water of several mine tailing ponds. The aims of the study were to define chemical properties of the mine spoils, determine the concentrations of heavy metals in different plant organs and assess the phytoremediation potential of common reed. The investigated sediments were notably rich in both total and available forms of Fe, Pb, Zn and Cu, with their upper concentrations close to phytotoxic levels. The greatest amounts of almost all of the investigated metals in plants from all three mine tailing ponds were found in the roots, with their concentrations positively correlated with the amounts of their available forms in the corresponding sediment. The far higher metal concentrations in the roots in comparison with other plant organs clearly indicate that the metals were strongly sequestrated within root cortical tissues and were not transferred across the endodermis. Taken altogether, the presence of the greatest amounts of metals in roots, high bioaccumulation factor and low translocation factor show that P. australis is an excluder plant species with a good phytostabilisation potential. As such, it might be efficiently used in rhizofiltration of wastewaters.

Aims Phragmites australis grows as a pioneer plant species in several mine and flotation tailings ponds distinguished by extremely high concentrations of metals. The main goals of this study were to estimate the effects of the specific concentrations and combinations of accumulated metals on the efficiency of antioxidative enzymes and plant oxidative status. This study is relevant to our understanding of the common reed exceptional capacity to endure extreme edaphic conditions. Methods Metal concentrations were determined in the sediment, roots and leaves. Antioxidative enzymes activities, amounts of pigments and phenolics, total antioxidative capacity (TAC), lipid peroxidation level (LP) were analysed in plant organs. Results Effects of accumulated metals depended on their concentrations and their stoichiometry. Antioxidative enzymes and TAC in roots were significantly reduced, resulting in consequent increase in LP. Pb concentration in leaves did not significantly change enzymes activities, whereas toxic level of Cu impeded activity of catalaze and ascorbate peroxidase. Conclusions The results indicate that in the conditions of high root metal contamination the mechanisms involved in their immobilization and detoxification cannot completely restrain their toxicity. Their effects on enzymes activities depend on the type of enzyme, metal concentrations, specific ratios and interactions.