Variations in microelement concentrations in the annual rings of Scots pine under different environmental conditions
2001
Paern, H. (Estonian Agricultural Univ., Tartu (Estonia). Forest Research Inst.)
Variations in the concentrations of Cd, Mn, Ni, Cr, Fe and Zn in the annual rings of Scots pines at five sites along an atmospheric pollution deposition gradient in Estonia were studied with respect to the different character and load of pollution. The concentrations of Cr and, to a lesser extent, Mn and Fe, had increased while those of Cd and Zn had decreased in the annual rings at the sites subjected to a higher pollution load. The concentrations of Cd, Mn, and Zn in the annual rings had decreased over time in all wood samples. A decrease in the level of Fe in the Rannapungerja, Kurtna and Narva sample was followed by an increase in sapwood in the Narva sample. The concentrations of Ni and Cr showed a great variability in all wood samples. The general trend in Ni levels showed an increase in the Rannapungerja, Kurtna, and Narva wood samples, followed by a decrease during the last decade. In the wood samples of the Haeaedemeeste and Tipu sites, the concentrations of Ni had generally decreased over time but had increased since the 1950s at the Tipu site. The levels of Cr were found to have decreased in the wood samples of Rannapungerja , Kurtna , and Narva, with a slight increase being observed during the last decades; in the wood samples of the Haeaedemeeste and Tipu sites, Cr concentrations have increased over time. For most of the elements analysed in this study, the concentration trends did not appear to be correlated with pollutant emissions, rather, they were suggestive of lateral movement in tree xylem. However, Fe may prove to be a sensitive bioindicator of historical atmospheric deposition
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