Stable Carbon and Oxygen Isotopes in Recent Sediments of Lake Wigry, NE Poland: Implications for Lake Morphometry and Environmental Changes

Abstract

The stable carbon and oxygen isotope records of the recent sediments from Lake Wigry are related to the diverse character of the main sub-basins of the lake with respect to bathymetry, hydrological conditions, and trophic state. The temporal variations of carbon and oxygen isotope data are also compared with the environmental changes in Lake Wigry watershed. In general, the differences in oxygen isotope compositions between studied carbonates indicate that δ18O values do not clearly reflect the local climate condition during the last few decades in studied region. This effect is assumed to result particularly from the various contribution of the inflow waters supplying the different part of Lake Wigry, which could alter the real isotopic signal of climatic changes preserved in sediments. In addition, the complex bathymetry and spatial variations in the intensity of biological productivity in the lake could also determine the discrepancy in the δ18O values. Further, the stable carbon isotope compositions of studied carbonates are considered to have been modified by hydrodynamic condition within the lake system, which is also a factor related to Lake Morphometry. Although the presented sediment profiles display an individual stable carbon isotope record, the sediments preserve the isotopic signal of primary productivity increase and changes in trophic state of Lake Wigry during the previous century.