Thallium hyperaccumulation status of the violets of the Allchar arsenic-thallium deposit (North Macedonia) confirmed through synchrotron µXRF imaging.

The abandoned Allchar Mine in the Republic of North Macedonia is a globally unique deposit with the highest known grades of thallium (Tl) and arsenic (As) mineralization. We aimed to determine the distribution of As and Tl in whole dehydrated shoots of the three Viola taxa using synchrotron micro-X-ray fluorescence analysis. Additionally, soil and plant organ samples were collected from all three Viola taxa at the Allchar site and analysed using inductively coupled plasma-atomic emission spectrometry. Concentrations of Tl were extremely high in all three Viola taxa (up to 58 900 mg kg-1), but concentrations of As were highly variable with V. tricolor subsp. macedonica and V. allchariensis having low As (up to 20.2 and 26.3 mg kg-1, respectively) and V. arsenica having the highest concentrations (up to 381 mg kg-1). The extremely high Tl in all three species is endogenous and not a result of contamination. Arsenic in V. tricolor subsp. macedonica and V. allcharensis is strongly affected by contamination, but not in V. arsenica where it appears to be endogenous. The pattern of As enrichment in V. arsenica is very unusual and coincides with Ca-oxalate deposits and Br hotspots. The results of this study could form the basis for more detailed investigations under controlled conditions, including plant dosing experiments.

Plantago subulata as indicator of potentially toxic elements in the substrate.

Plantago subulata is a facultative serpentinophyte, with predominantly ultramafic distribution in Serbia and Montenegro. The plant samples were collected from ultramafic and non-ultramafic substrate, including two abandoned mining sites, with the aim to assess the accumulation potential of this species. The samples were collected from 10 sites in Serbia and Montenegro and element concentrations in plants and soils were determined. Particularly high concentrations of Fe, Cu, Mn, Zn, and Cd were found in the soil and plant samples from an abandoned iron mining site, Mt. Kopaonik, Suvo Rudiste. The concentrations of Ni, Cr, Fe, Co, and Cd were statistically different between soil and plant samples from ultramafic and non-ultramafic bedrock. Considering the fact that concentrations of Zn, Ni, and Cr in roots and shoots were positively correlated with their respective contents in the soil, i.e., the chemical composition of the plant and soil samples reflected the characteristics of the substrate, and for most of the elements analyzed, P. subulata acted as indicator species. For Cd and Pb, only the root concentrations were positively correlated with soil content, indicating exclusion and root sequestration as the main tolerance strategies for these elements. Although below the hyperaccumulation threshold, a strong accumulation capacity of P. subulata was found for Ni and Cu.

Accumulation of trace elements in Tussilago farfara colonizing post-flotation tailing sites in Serbia.

The purpose of this study was to examine the accumulation potential of spontaneously developed Tussilago farfara populations colonizing sites with different levels of anthropogenic pollution. Physical characteristics of the soil are presented, together with the concentrations of macroelements and microelements (Ca, Mg, Fe, S, Al, Pb, Zn, Cu, Cd, Mn, As, Sb, Ag, Ti, and Sr) in both soil and plants. The biological concentration, accumulation, and translocation factors were used to assess the potential for heavy metal accumulation. Considerable differences were found among assessions from unevenly contaminated habitats, particularly in comparison with an unpolluted site. In line with the ore's characteristics, substrate samples from polluted sites were heavily contaminated with Pb, Zn, As, and Sb. Increased levels of microelements were also detected in plant samples from flotation tailings. Despite active absorption of Zn, Cu, Cd, Mn, and Sr by the plants from mining sites, the detected quantities of these elements in all samples were below the hyperaccumulation threshold. However, the obtained results indicate that the use of T. farfara from such sites in traditional medicine could pose a risk to human health due to accumulation of several toxic elements in the plant's aboveground tissues. Additionally, as a successful primary colonizer and stabilizer of technogenic substrates, T. farfara has an important role in the initial phases of revegetation of highly contaminated sites.

Micro-edaphic factors affect intra-specific variations in trace element profiles of Noccaea praecox on ultramafic soils.

The aim of this study was to compare trace element profiles of Noccaea praecox (Wulfen) F. K. Mey. growing on ultramafic soils in different habitat types and to observe differences in uptake and translocation of trace elements. Physico-chemical characteristics of the soil and concentrations of P2O5, K2O, Ca, Fe, Mn, Zn, Cu, Ni, Cr, Pb, Cd, and Co in plant samples were presented. Biological concentration, accumulation, and translocation factors were calculated to estimate accumulation potential of different N. praecox accessions. All of the studied accessions were Ni hyperaccumulators (with shoot concentrations up to 14,593 mg kg-1), but with notable differences in accumulation and translocation rates. Significant differences in accumulation and translocation patterns of trace elements were observed among accessions from habitats characterized as serpentine steppes on dry, shallow soils in contrast to the accessions from habitats with higher soil moisture, and higher content of organic matter.