Influence of transboundary transport of trace elements on mountain peat geochemistry (Sudetes, Central Europe)

Abstract

Mountain ombrotrophic peatlands in Central Europe are an important stock of transboundary contamination both of natural and anthropogenic origin. The Snie_zka Mountain (West Sudetes) forms a significant orographic barrier and receives aerosols from broadly-recognized anthropogenic sources (production and use of stainless steel, processing of uranium, coal combustion, nuclear weapon tests, and Chernobyl accident). The main objective of the study was to assess the pattern of distribution and origin of trace elements and to distinguish the long-range transport vs. local signals in two 210Pb and 14C e dated peat cores from the highest summit of the Karkonosze (West Sudetes) spanning the last 280 years. Maximum values and accumulations of almost all investigated elements (Pb, Zn, Cu, Ni, Cr, Ti, Al, U, Sc, and REE) were identified around the 1970s. The analysis of peat using scanning electron microscopy (SEM) confirmed the occurrence of spheroidal aluminosilicate fly ash particles (SAP) in the topmost 40 cm (from AD 1938) together with a maximum of mullite (3Al2O3$2SiO2), an anthropogenic marker originating from coal-based power plants. The overall 206Pb/207Pb signature ranges from 1.160 to 1.173, indicating a predominant contribution of anthropogenic Pb. Human activities promote the release of mobile 234U, due to the weaker bonds to mineral structure, and cause the radiogenic disequilibrium between 238U and its daughter 234U.