Spatial variability of sedimentological properties in a large Siberian lake

Abstract.

The analysis of spatial variability of lake sediment properties in Lake Lama, Central Siberia is presented. The aims were to characterize the spatial structure in lake sediment composition, to determine major spatial patterns of sediment properties by calculating estimates at locations where no samples were available, and to assess the main processes determining these patterns. Sediment properties were measured at 71 spatially distributed locations in the lake, comprising particle size distribution, biogeochemical properties such as total organic carbon, total nitrogen or stable carbon isotopes, as well as geochemical distribution of major and trace elements. Spatial analysis consisted of a principal components analysis and, subsequently, calculation and modelling of variograms to describe the spatial structure in the data as well as determination of spatial estimates using block-kriging to map spatial structure. The results showed that particle size, biogenic silica, CaO, δ¹³C_org, Zr and TOC/TN ratio were a major source of variability in sediment properties and, thus, dominate the sediment structure in Lake Lama. Major anomalies occurred near river inlets, depending on river size and its position as well as slope of the river bed. Other anomalies were associated with water depths, morphology of the lake basins, and wind-induced currents and re-suspension in the shallow part of the western basin. The spatial structure in sediment properties indicate that several processes act at different spatial scales. Moreover, there was a considerable amount of smallscale variability that could not be quantified due to sampling design. The results showed that heterogeneity in lake sediment composition is a main characteristic of large lake systems, and must be taken into account, especially in paleolimnological and environmental applications.