The presence of cacodylic acid (dimethylarsinic acid, DMA) can be an important factor in limiting the abilities of young tree seedlings to adapt to unfavorable environmental conditions. For this reason, the aim of the study was to estimate the influence of different DMA additions (from 0.01 to 0.6 mM) to modified Knop solution to arsenic (As) and selected forms of this metalloid (As(III), As(V), DMA) phytoextraction by two-year-old Acer platanoides L. and Tilia cordata Miller seedlings. Additionally, the biomass and other elements important in As transport in plants were analyzed. Seedlings of both tree species were able to grow in all experimental systems except the one with the highest DMA concentration (0.6 mM). Exposure of tree seedlings was related to a general decrease in plant biomass. Phytoextraction of As in roots, stems, and leaves increased with a rise of DMA concentration in solution to the highest content of As in A. platanoides and T. cordata roots growing under 0.3 mM (135 ± 13 and 116 ± 14 mg kg⁻¹ dry weight). Arsenic was accumulated mainly in roots, thereby confirming bioconcentration factor values BCF > 1 for all tree seedlings treated with DMA. Exposure of plants to low DMA concentrations (0.01 and 0.03 mM) was related to the transport of this element to aboveground parts, while increased DMA concentration in other experimental systems led to the limitation of As transport to stems, as confirmed by translocation factor values TF < 1. Changes in many other elements such as boron, silicon, phosphorus, or sulfur concentration indicated the possible influence of DMA on the transport of As from roots to leaves. The obtained results show that DMA can be an important factor in modulating As phytoextraction in the studied tree species.

The aim of the study was to compare the phytoextraction abilities of six tree species (Acer platanoides L., Acer pseudoplatanus L., Betula pendula Roth, Quercus robur L., Tilia cordata Miller, Ulmus laevis Pall.), cultivated on mining sludge contaminated with arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), thallium (Tl), and zinc (Zn). All six tree species were able to survive on such an unpromising substrate. However, A. platanoides and T. cordata seedlings grown on the polluted substrate showed significantly lower biomass than control plants (55.5 and 45.6%, respectively). As, Cd, Cu, Pb, and Tl predominantly accumulated in the roots of all the analyzed tree species with the following highest contents: 1616, 268, 2432, 547, and 856 mg kg⁻¹, respectively. Zn was predominantly localized in shoots with the highest content of 5801 and 5732 mg kg⁻¹ for U. laevis and A. platanoides, respectively. A. platanoides was the most effective in Zn phytoextaction, with a bioconcentration factor (BCF) of 8.99 and a translocation factor (TF) of 1.5. Furthermore, with the exception of A. pseudoplatanus, the analyzed tree species showed a BCF > 1 for Tl, with the highest value for A. platanoides (1.41). However, the TF for this metal was lower than 1 in all the analyzed tree species. A. platanoides showed the highest BCF and a low TF and could, therefore, be a promising species for Tl phytostabilization. In the case of the other analyzed tree species, their potential for effective phytoextraction was markedly lower. Further studies on the use of A. platanoides in phytoremediation would be worth conducting.

The aim of the study was to estimate the significance of the role of arsenite (As(III)), arsenate (As(V)), and dimethylarsinic acid (DMA) presence in modified Knop medium in the efficiency of phytoextraction of arsenic (As) in Acer platanoides root, stem, and leaves. The addition of particular As forms in single, double, and triple experimental systems was associated with a lower increase of seedling biomass compared to control plants (system free of As forms addition). Depending on As forms and their concentration in solution, negative symptoms from slight visible changes (inorganic forms separately or jointly), through smaller and discolored leaves (after DMA addition), and finally to their withering (after high DMA addition) were observed. Changes of color and shape for root systems exposed to particular As forms separately or jointly were also observed, in spite of the fact that there were no significant changes in biomass of seedlings growing in all experimental systems. The highest mean concentrations of As in root, stem, and leaves (590, 70, and 140 mg kg⁻¹ dry weight (DW), respectively) were observed in plants growing under different experimental systems. The highest bioconcentration factor values were 10.8 for plants exposed to 0.06 mM of As(III) and DMA, while the highest translocation factor (1.0) was recorded for plants growing under the same As forms (0.6 and 0.06 mM, respectively). The obtained results indicate that the presence of particular As forms not only determines As phytoextraction and transport of this metalloid form but also has a decisive influence on plant morphology and survivability. As regards the practical aspects of phytoremediation, the kind of As forms present in substrate are more important than their total concentration.

In this paper, we present the results of mercury concentration in soils, buds and leaves of maple (Acer platanoides—Ap) and linden (Tilia platyphyllos—Tp) collected in four periods of the growing season of trees, i.e. in April (IV), June (VI), August (VIII) and November (IX) in 2013, from the area of Poznań city (Poland). The highest average concentration of mercury for 88 samples was determined in soils and it equaled 65.8 ± 41.7 ng g⁻¹ (range 14.5–238.9 ng g⁻¹); lower average concentration was found in Ap samples (n = 66): 55.4 ± 18.1 ng g⁻¹ (range 26.5–106.9 ng g⁻¹); in Tp samples 50.4 ± 15.8 ng g⁻¹ (range 23.1–88.7 ng g⁻¹) and in 22 samples of Tp buds 40.8 ± 22.7 ng g⁻¹ (range 12.4–98.7 ng g⁻¹) and Ap buds 28.2 ± 13.6 ng g⁻¹ (range 8.0–59.5 ng g⁻¹). Based on the obtained results, it was observed that the highest concentration of mercury in soils occurred in the centre of Poznań city (95.5 ± 39.1 ng g⁻¹), and it was two times higher than the concentration of mercury in other parts of the city. Similar dependencies were not observed for the leaf samples of Ap and Tp. It was found that mercury concentrations in the soil and leaves of maple and linden were different depending on the period of the growing season (April to November). Mercury content in the examined samples was higher in the first two research periods (April IV, June VI), and then, in the following periods, the accumulation of mercury decreased both in soil and leaf samples of the two tree species. There was no correlation found between mercury concentration in leaves and mercury concentration in soils during the four research periods (April–November). When considering the transfer coefficient, it was observed that the main source of mercury in leaves is the mercury coming from the atmosphere.