Recent Lithuanian peri-urban ombrotrophic bog records: indices derived from the contents of lead, zinc, copper and nickel

Two Lithuanian c . 50-cm long peat cores from ombrotrophic bogs were analysed, namely, Rėkyva near Siauliai and Žudiskės near Vilnius. Ash content, bulk density, chemical element concentrations determined by EDXRF and 210 Pb dating by gamma spectrometric methods were used. Geochemical data of deep Rėkyva peatland mine layers, dated by 14 C to the BC/AD boundary, enable the estimation of reference values for the calculation of increase coefficients (IC) in the young (formed after 1900) layers of cores, where IC values exceed 26.3 for Pb, 2.9 for Zn, 2.4 for Cu and 2.3 for Ni. The young layers compared to the older ones are characterized by an increase of ash and most elemental contents and the disappearance of a positive correlation between ash and Pb, Zn, Cu, Ni contents. Higher median values of IC and the anthropogenic accumulation rate (AR) in young Rėkyva are predetermined mainly by soil dust, higher median enrichment factors (EF) of Zn, Cu, Ni and median percentages of their anthropogenic component by higher industrialization of Vilnius and the leeward location of Žudiskės. The timing of maximum or next high EF and anthropogenic AR (mg m –2 yr –1 ) of Pb (10.1), Zn (7.0), Cu (1.1), Ni (1.2) in Žudiskės (1970-1974) corresponds to general results over Europe.