Phytoaccumulation of Heavy Metals in Flowers of Tilia cordata Mill. and Soil on Background Enzymatic Activity

The phytoaccumulation of Fe, Mn, Cu, Zn, and Pb in Tilia cordata flowers and soils from six locations with varying degrees of anthropopressure in Bydgoszcz city and its surroundings (Poland) was assessed. Additionally, metal concentrations and soil enzymatic activity were analyzed. Enrichment Factor analysis revealed significant Zn enrichment at only one locality, supported by a geoaccumulation index value indicating moderate soil pollution. Total metal content in soils correlated with total organic carbon (TOC), while total iron content correlated with the clay fraction (<0.002 mm). Metal concentrations were comparable to the geochemical background levels for soils in Poland. Assessment of total metal contents in the topsoil surface layer from the six locations indicated that concentrations did not exceed permissible limits established by applicable legislation. The study showed that sampling locations influenced the activities of dehydrogenase (DHA), fluorescein diacetate hydrolysis (FDA), β-glucosidase (GL), and arylsulfatase (AR), and these activities correlated more strongly with pedogenic factors than with metal content. No elevated metal levels were detected in the dry mass of T. cordata flowers. Lead content did not exceed 10 mg·kg−1 dry matter, in accordance with World Health Organization (WHO) recommendations. Continued monitoring of trace element levels in soils and T. cordata flowers, particularly in urban environments, is advisable.