The Historical Record of Atmospheric Pyrolytic Pollution over Europe Registered in the Sedimentary PAH from Remote Mountain Lakes

Abstract

Historical records of the deposition fluxes of polycyclic aromatic hydrocarbons (PAH) in 10 remote high altitude lakes distributed throughout Europe have been studied. Cores from each site were dated radiometrically, and the results were used for the reconstruction of the pollutant changes between 1830 and present. In general, both PAH pyrolytic fluxes and concentrations (Σ = 23 compounds) increased from uniform background levels (5−30 μg m-2 yr-1, 20−100 ng g-1 dw, respectively) at the turn of the century to maximum values in 1960−1980. After these peak values a slight decrease to present day levels has been observed in some lakes, though they are still 3−20 times greater than the preindustrial period. Distinctive features in the downcore PAH profiles and concentrations between sites allowed for differentiation between five regions in Europe: peripheral areas (Norway and the Iberian Peninsula), Pyrenees and western Alps, central Alps, Tatra Mountains, and the Arctic. Atmospheric PAH inventories were estimated from the vertical integration of sedimentary inventories using 210Pb to correct for postdepositional transport processes. This approach consistently reduces variability among lakes from the same region. The results obtained define the lakes in the Tatra mountains and that on Spitsbergen Island as those of highest and lowest atmospheric PAH input. The other lakes exhibit lower differences although their atmospheric inventory values group consistently with the above-mentioned regions.