Heavy metal concentrations in oak wood growth rings from the Taunus (Federal Republic of Germany) and the Valdivia (Chile) regions

Queirolo F, Valenta P, Stegen S, Breckle S-W. Heavy metal concentrations in oak wood growth rings from the Taunus (Federal Republic of Germany) and the Valdivia (Chile) regions. Trees. Structure and Function. 1990;4(2):81-87.Using a voltammetric procedure described previously, the radial distribution of Cd, Cu, Pb and Zn in annual growth rings of oak from two regions has been investigated: an unpolluted region in Valdivia (Chile) and a polluted region in Konigstein (Taunus, FRG). The very low metal levels found in oak wood from the Valdivia region have necessitated that the method be improved and its accuracy tested with standard reference materials and by comparison with electrothermal atomic absorption spectrometry as an independent method. The radial distribution of the four metals investigated is similar in oaks from both regions. No significant differences have been observed in the average concentrations of the essential metals Zn and Cu in the oak tree rings from the two investigated regions. For the toxic metals Cd and Pb, however, a significant increase by a factor of 2 for Cd and by a factor of 12 for Pb has been found when comparing the Konigstein and the Valdivia regions. This is evidence of expected pollution of the Konigstein region by Pb and, to a lesser extent, by Cd since 1940 or earlier. The trees in both regions can be classified as sound (damage degree 0-1 in Konigstein)