Irrigation of cultivated plants can be a source of toxic lithium to plants. The data on the effect of lithium uptake on plants are scant, that is why a research was undertaken with the aim to determine maize ability to bioaccumulate lithium. The research was carried out under hydroponic conditions. The experimental design comprised 10 concentrations in solution differing with lithium concentrations in the aqueous solution (ranging from 0.0 to 256.0 mg Li ∙ dm-3 of the nutrient solution). The parameters based on which lithium bioretention by maize was determined were: the yield, lithium concentration in various plant parts, uptake and utilization of this element, tolerance index (TI) and translocation factor (TF), metal concentrations in the above-ground parts index (CI) and bioaccumulation factor (BAF). Depression in yielding of maize occurred only at the highest concentrations of lithium. Lithium concentration was the highest in the roots, lower in the stems and leaves, and the lowest in the inflorescences. The values of tolerance index and EC50 indicated that roots were the most resistant organs to lithium toxicity. The values of translocation factor were indicative of intensive export of lithium from the roots mostly to the stems. The higher uptake of lithium by the above-ground parts than by the roots, which primarily results from the higher yield of these parts of the plants, supports the idea of using maize for lithium phytoremediation.

The paper presents current reports on kinetics and mechanisms of reactions with mercury which take place in the exhaust gases, discharged from the processes of combustion of solid fuels (coals). The three main stages were considered. The first one, when thermal decomposition of Hg components takes place together with formation of elemental mercury (Hg0). The second one with homogeneous oxidation of Hg0 to Hg2+ by other active components of exhaust gases (e.g. HCl). The third one with heterogeneous reactions of gaseous mercury (the both - elemental and oxidised Hg) and solid particles of fl y ash, leading to generation of particulate-bound mercury (Hgp). Influence of exhaust components and their concentrations, temperature and retention time on the efficiency of mercury oxidation was determined. The issues concerning physical (gas-solid) and chemical speciation of mercury (fractionation Hg0-Hg2+) as well as factors which have influence on the mercury speciation in exhaust gases are discussed in detail.