Distribution of thallium and accompanying metals in tree rings of Scots pine (Pinus sylvestris L.) from a smelter-affected area

Distribution of Tl, Zn, Cd, Pb, K, Ca, Mg and Mn and Pb isotopic composition in tree rings of Scots pine (Pinus sylvestris L.) from an area affected by primary Zn smelting (Olkusz, southern Poland) were investigated. Elevated concentrations of Tl (up to 0.8 mg kg−1) in pine trees imply that conifers tend to accumulate this metal to some extent. A generally positive relationship between soil and tree-ring Tl levels was identified. The Tl patterns in stem wood did not correspond to changes in Tl deposition; the lateral translocation of Tl in the sapwood and its accumulation at the sapwood-heartwood boundary (i.e., in the inner sapwood) is suggested. It is probable that the specific behavior of Tl in trees results from its biogeochemical analogy with K. In contrast, tree-ring patterns of Zn and Cd significantly correlated with their deposition; nevertheless, a partial shift of these metals towards the stem center cannot be excluded. The isotopic composition of Pb (206Pb/207Pb ~ 1.172–1.184) in trees and underlying soils revealed the predominant influence of smelter emissions (206Pb/207Pb ~ 1.17) on Pb contamination. Analysis of main nutrients (Ca, Mg and Mn) in wood reflected environmental changes related to acid deposition.

Research Highlights
► Elevated concentrations of Tl in the pine trees studied imply that conifers tend to accumulate this metal.
► The Tl patterns in stem wood did not correspond to historical deposition; preferential accumulation of Tl at the sapwood–heartwood boundary is suggested.
► The specific behavior of Tl in trees results probably from its biogeochemical analogy with K.
► The use of conifers as environmental archives of Tl inputs seems to be inappropriate.