Pobór i opróbowanie powierzchniowych, silnie uwodnionych osadów jeziornych o nienaruszonej strukturze — uwagi metodyczne i stosowany sprzęt

Abstract

Coring and subsampling of undisturbed recent lake sediments with high water content — remarks about methodology and equipment.S u m m a r y. This study presents some remarks about coring and sectioning cores of recent lake sediments. Effective coring of such sediments is not easy because they are very loose (water content usually exceeds 90%). Precisely taken core should consist of near-bottom water and undisturbed sediment column. The most widely used are gravity corers which are simple in construction and operation. The gravity corer presented here is additionally equipped with percussion system to improve penetration into the sediment. It enables to take cores 94 mm in diameter and up to 90 cm in length. The corer with rubber stopper blocked is lowered through the water and pushed into the sediment. While retrieving the core, the stopper settles into the top of the core tube. At the surface, the plug is inserted into the bottom of the core tube. After collecting, the core should be extruded and sectioned. A device presented here enables to divide the core into short intervals (0.5–1 cm). The core is extruded upwards and samples can be collected from the tray placed on top of the tube. Both the corer and the extruder are relatively small and light. This equipment have been used in the Department of Geomorphology & Quaternary Geology at Gdańsk University for several years. So far, cores from more than 60 lakes of various depths (up to 50 m) have been successfully taken.