This paper presents the dating results and basic analyses of recent sediments from Lake Piaseczno. The age of sediments was determined using the ²¹⁰Pb method and constant flux : constant sedimentation (CF : CS) model. The estimated timescale was in agreement with the AMS¹⁴C date from the base of the core. The mean sediment accumulation rate during the last 100 years was calculated as 0.025 g cm^–2 a^–1. Based on the radiocarbon date, the rate of sediment accumulation below the ²¹⁰Pb dating horizon was estimated as 0.066 g cm^–2 a^–1. The variability of main physical properties and sediment components along the core was analysed as well. The sediments were characterised by a very high water content (>80%). Carbonates were either not present or at a very low level (<1%). However, organic and minerogenic matter variability represents an interesting record of increasing erosion intensity in the catchment area. Analysis of archival cartographic materials demonstrated that the most likely reason for the enhanced transport of minerogenic matter to the lake was deforestation caused by human activity in the beginning of the 20th century.

Keywords: lake sediments, 210Pb, sedimentation rates, erosion changes, deforestation, southeastern Poland