A NEW APPROACH TO OBTAINING STRATIGRAPHICALLY UNDISTURBED COLUMNS OF BOTTOM SEDIMENTS IN SHALLOW WATER BODIES

The new universal sampler for selection of cores of bottom sediments in shallow reservoirs from low-dimensional vessels or from ice is presented. The tube is immersed manually by means of a partitioned boom. The immersion into the sediment depending on its softness/ denseness is produced by pressing or by rotating. For that, the tube is equipped with detachable tips – either a smooth nose cone, or an auger bit, respectively. The tube has a plastic liner inside and an orange peel closing system similar to those used in gravity corers but installed in a different way, taking into account the safety of thin-wall details during drilling. To do this, the orange peel rotating along with the tube is placed fully opened in spacing between the tube and the liner, that excludes its contact with the sample during immersion into the liner. To lock the core, the liner at the beginning of the recovery moves upwards so that the orange peel can close. As a result, it is possible to select cores with undisturbed structure on different types of sediment, except for dense gravel. The efficiency of the new sampler was confirmed by its successful use from motor catamaran and ice in studies of bottom sediments of the Curonian and the Vistula Lagoon and of the 25 m deep lake in the spent amber quarry. The sampler can be used in marine sedimentology, limnology, and geoecology to determine the physico-mechanical, chemical and other characteristics of bottom sediments.

Instrumenting Giant Piston Corers: A Decisive Step in Understanding the Coring Process and Interpreting Data

Giant piston corers were introduced to the marine geotechnical site investigations market towards the end of the nineties. Such corers are also used for scientific studies by research institutes as Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER). Cores were observed to show distortion or mismatches between core length and the position of the sample in the soil. The instrumentation of corer provides valuable information on the behaviour of the corer. The instrumentation also allows the correction of sample length to its true penetration. This paper: • Describes the instrumentation now permanently mounted on the STACOR® giant piston corer • Presents the installation of sensors, • Describes the data interpretation, • Provides some recommendations for extending this monitoring to other large gravity corers.