Evaluation of ombrotrophic peatland environment as tracer of past atmospheric deposition

We studied Šijec bog on Pokljuka plateau. Using geophysical methods (GPR, ERT), we determined the subsurface morphology of the peatland and created a formation model, which indicates different development stages of the peatland. Peatland is composed of four depressions which vary in depth, surface topography, and water saturation at the surface. Atmospheric mineral matter input to the peatland is mainly composed of silicates, carbonates, organic particles and Fe-oxyhydroxides. Mineral matter deposited on the acidic, organic matter-rich peatlands surface can be partially or totally dissolved. Dissolved and solid mineral matter can be retained through plant uptake, physical entrainment, or complexation by organic matter. Chemical composition of peatland outflow water reveals significant removal of elements like Al, Fe, and REE which are soluble in acidic environment or mobile in their reduced state. Metals (e.g. As, Cr, Cu, Ni, Pb) remain in surface pool waters and upper layers of peat due to lower solubility in peatland environment and binding to organic matter. Geochemical analysis of peat confirmed differences between development stages, which were further emphasised with water geochemical composition indicating additional water and mineral matter sources in NW area of the peatland. Comparison of C/N ratios and trace element distributions along peat profile reveals elevated content of elements like As, Hg, and Pb in upper peat layers due to anthropogenic influence and peat decomposition, and its related loss of organic matter. Peat cores show large variabilities in element content among sampling locations, showing the importance of holistic approach to research of peatland environment.