Spatio-temporal differences of sediment accumulation rate in the Lake Gościąż (Central Poland) as a response of meteorological conditions and lake basin morphometry

Abstract

Weather conditions and lake basin morphometry are of key importance in the study of sediment accumulation rate in lakes. This study aims to determine how these factors affect spatial and seasonal variations in sedimentation rate in the epilimnion and hypolimnion of Lake Gościąż. To determine sedimentation rates, six sedimentation traps were set up at different locations and depths in the lake. Weather data were obtained from a meteorological station near the lake. Furthermore, temperature in the lake water column was measured continuously, and during field work oxygenation and transparency were also measured. Seasonal changes in sediment composition were analyzed on smear slides under microscope. The study showed that sedimentation rate increased as bottom steepness increased, and that there was more sediment in the hypolimnion than the epilimnion, especially in spring and autumn. There was a clear seasonal variation in early-spring and autumn peaks in sedimentation. The obtained results were significantly dependent on bottom relief, wind and air temperature through these factors’ influence on water temperature. The results show that the sediment accumulation rate in Lake Gościąż depends on the hydrodynamic conditions, which are determined by wind speed, wind direction, water temperature, and the shape and steepness of the lake basin. The relief features of the lake bottom and its orientation relative to the prevailing wind are significant factors in the spatial differentiation in sediment accumulation rate and composition of sedimenting material. It has been shown that the lake’s shallow-water zone (littoral and sublittoral) is an important source of the material accumulated in the profundal zone. The patterns and mechanisms of the course of contemporary sedimentation in Lake Gościąż, as determined based on the conducted investigations, can be applied in the study of other lakes and in assessing the representativeness of sampling sites for laminated bottom sediments to be used in palaeo-environmental studies.

Keywords

• lake morphometry
• dimictic lake
• sediment resuspension
• sediment accumulation rate
• hydro-meteorological monitoring