Cadmium and Lead Deposition around a Swedish Battery Plant as Recorded in Oak Tree Rings
- Mats Eklund *
In this study, results from the elemental analysis of Cd and Pb in oak (Quercus robur L.) tree rings are compared with emission estimations based on company and official statistics for the major producer of Ni-Cd accumulators in Sweden, NIFE. The NIFE plant in Fliseryd was in operation from 1910 to 1974, handling and thereby emitting large quantities of Cd. In 1942, the company also took up recycling Pb from various sources. The Cd and Pb content in control trees, situated far from point sources, varied between 20 and 30 µg/kg without any obvious temporal trend for Cd and 20 to 200 μg/kg with an increasing temporal trend for Pb during the 20th century. These values represent regional background levels resulting from natural and diffuse sources. Cores from 18 trees, situated less than 2 km away from the factory were sampled. The variation in absolute figures between different trees was in some cases large, but the temporal trend within each tree showed a consistent similarity to the trend of the estimated emissions. The Cd values were up to one magnitude higher than in the reference trees, and the highest values were always found in the latest segment, formed from 1980 to 1990. A significant uptake through the roots from the polluted soil after the factory close down must therefore have taken place. The Pb content of the sampled trees in a few cases exceeded 3000 μg/kg, but the highest values were never found in the latest 10-yr segment. Despite large intertree variation and difficult interpretations, the tree-ring analysis seems to have great potential as a tool for the study of both temporal and spatial dimensions of historical Cd and Pb emissions.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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