Distribution and quantification of Pb in an evergreen broadleaved forest in three hydrological years

The distribution, quantification and fluxes of Pb were examined in an evergreen broadleaved forest in western Greece for three hydrological years. More specifically, concentrations and annual fluxes of Pb were determined in bulk and throughfall deposition as well as litterfall. The Pb concentrations were also measured in forest floor and mineral soil up to 80 cm and the isotopic ratios of 206 Pb/ 207 Pb were determined in soil layers and the parent rock material. High variability in the fluxes of the metal among the three hydrological years were found, evidence of the variability of Pb deposition in time. Litterfall fractions with a large surface area, like holm oak flowers, had high Pb concentrations. Applying a steady state model and considering the Pb amounts in throughfall and litterfall as inputs on the forest floor, the mean residence time of Pb in the forest floor was 94 years with a coefficient of variation equal to 41%. More observations are needed to lower the variability of the mean residence time. The isotopic ratio in the rock material was defined as the lithogenic ratio. The statistical tests showed that the petrol derived Pb migrated to the depth of 20 cm and its percentages in the soil pedon was in the range of 62% in the L horizon to 11% in the 10–20 cm layer. In higher depths (> 40 cm) preindustrial anthropogenic Pb affected the isotopic ratio. As the forest under consideration is remote from industrial activities, the results can serve as a baseline for future studies on Pb distribution and quantification.