Comprehensive study of the mountainous lake sediments in relation to natural and anthropogenic processes and time (Mały Staw Lake, Poland)

Abstract

The Sudety Mts. form a chain of mountains in the South of Poland and during the last 200 years were subjected to strong industrial and agricultural pressure. The records of these human-induced changes are stored in natural archives like lake sediments. For the comprehensive study, three sediment cores taken from Mały Staw Lake (Sudety Mts.) were analyzed for the concentration of K, Na, Mn, Fe, Cu, Mg, Zn, Cd, Cr, Ni, Pb and radioactivity of ¹³⁷Cs and ²¹⁰Pb. As a result of the studies, the bathymetry map was developed and the sources of solid material supplied to the lake were identified. The geochronology studies of the cores were performed using ²¹⁰Pb method, to evaluate model of time changes in the sediment. Radioactivity of ²¹⁰Pb _uns (determined indirectly by ²¹⁰Po) ranged from 1051 ± 64 to 12 ± 8 Bq kg ⁻¹. The ¹³⁷Cs radioactivity was determined directly by gamma spectrometry and varied from 525 ± 37 Bq kg ⁻¹ for top layers to 9.80 ± 5.40 Bq kg ⁻¹ for the bottom of the core. Two characteristic peaks of ¹³⁷Cs radioactivity related to the global fallouts after nuclear weapons testing and the Chernobyl accident were observed and used to confirm ²¹⁰Pb dating method. Chemometrics analysis of the chosen metal’s concentrations combined with sample dating showed distinct imprint of human activity on the studied area.