The aim of our study was to evaluate the mobility of Zn in soils subjected to the activity of a zinc smelter and to assess the contamination of 1- and 2-year-old needles of Scots pine species sensitive to and tolerant of heavy metal contamination, particularly zinc. The trees were selected on the basis of their morphology, i.e., tolerant ones exhibited quite normal growth shape, but sensitive ones were more or less dwarves. Mineralogical composition revealed the prevalence of kaolinite in all soils except for two samples, where smectite dominated. Zinc contamination exceeded 30 times the geochemical background, and the reactive Zn forms represented 34.6% of total Zn content (Zn_Total). Proton generation capacity (α) indices calculated for the bioavailable Zn fraction (Zn_Bio) were 59% higher compared to the reactive Zn pool (Zn_Reac). Two-year-old tolerant (T) pine needles accumulated 21.9, 38.2, and 13.6% more Zn, Fe, and Mg, respectively, as compared to 1-year-old ones. For sensitive (S) needles, the range followed: 12.4, 48.8, and 7.3%, respectively. Iron was considered a “strategic survival element” for both pines growing under high zinc pollution.
The transfer of Zn ions from the soil environment to plants still remains the basic source of maintaining its high concentrations in the needles, since air emissions ceased in 1996. The amounts of Zn accumulated by Scots pine at crucial years of metallurgical emissions may be considered as an additional time-constant source due to the evergreen vegetative lifecycle.