Patterns of heavy metal accumulation in Taraxacum officinale

Medicinal plants growing in urban and industrialized environments can accumulate heavy metals (HM), which poses potential risks to both ecosystem functioning and human health. Taraxacum officinale Wigg., a widespread species frequently used as medicinal raw material, is commonly exposed to anthropogenic impacts, yet the mechanisms governing heavy metal uptake, retention, and translocation within this plant remain insufficiently constrained. This study assessed heavy metal (Cd, Cr, Cu, Mn, Ni, Pb, Zn) accumulation and their internal distribution in T. officinale growing under industrial pressure. Plants collected from background and impacted areas of the Novosibirsk Region, Russia, were analyzed for total content of heavy metals and their weakly bound compounds in belowground and aboveground organs. The effectiveness of HM plant uptake was assessed using bioaccumulation and translocation coefficients. The results demonstrate that two of the analyzed metals (Cd and Cu) exceeded the maximum permissible levels in plant tissues. The ranges of the translocation factor for Cu, Mn, Ni, and Pb were similar, indicating a pronounced tendency of T. officinale to retain these elements in the root system. Lower metal contents in aboveground parts compared with roots are probably due to physiological conditions. In contrast, Cd showed the most intensive accumulation in aboveground tissues, whereas Cr demonstrated significant retention by the roots. For metals except Cd, bioconcentration factor (BCF) values in roots were higher than in leaves at all studied sites. BCF values for Mn, Ni, Cr, and Pb (in all soils studied) in the aboveground parts of T. officinale were below 1. The ranges of TF values for Cu, Mn, Ni, and Pb showed a tendency of T. officinale to preferentially accumulate these elements in the roots.