THE DESIGN AND PERFORMANCE OF A NEW BOX CORER FOR COLLECTING UNDISTURBED SAMPLES OF SOFT SUBAQUATIC SEDIMENTS

'Baikal' sediment box corer represents an innovation in design of the closing mechanism and involves a single, thin, and flexible stainless steel blade rather than closing jaws. With this light-weight box corer only a relatively small cross-sectional area is offered to the sedime nt, allowing easier penetration. The closure blade is propelled smooth ly across the base of the box in a downwardly convex path by a set of constant force springs. Depending on choice of blade-release mechanism s, the corer can either be triggered immediately as the support cable slackens, after a delay of a few seconds, or immediately upon retrieva l. The box corer has been used successfully to sample poorly consolida ted sediments in freshwater lakes over a depth range of 8 to 1624 m. C ores of deep-water surficial sediment from Lake Baikal were tested for representativity and replicability by profiling natural and artificia l radioisotopes and lithostratigraphic features.