Sediment Samplers

 

A variety of sediment samplers are for recovering different types of sediment mainly based on their stiffness. Soft sediments are usually collected using short cores with wide barrels that do not disturb the sediment-water interface. Corers with deeper penetration usually encounter sediment with increasing stiffness and therefore need greater weight or other features, such as vibration or rotation to enable deeper penetration.

 

Simple gravity corers consist of a plastic liner inside a steel barrel with a weight on top that penetrates soft sediment by gravity. Water inside of the tube evacuates through a valve at the top. The wider the barrel the less disturbance and better penetration, in general. We plan to use a kasten-corer type that has a square barrel and are known to recover the sediment-water interface very well. Soft sediment can also be collected with the SIR.

 

This is a corer has a cutting shoe made of steel protecting the core liner inside a steel barrel. It is able to recover up to 3m of sediment depending on the stiffness and the number and size of clasts in the sediment.

A percussion sediment corer owned by NIU has been designed to permit recovery of up to 5m-long cores of stiff sediment. The tool will have some shared components and sensors GIPSIE. It is designed to fit through a 20cm (8in) borehole, and is a complementary technology to the SIR in that it can be used to collect larger samples from areas of particular interest as identified through SIR investigation.

 

This corer has an active hammer system driven by a water pump, which allows active penetration into stiffer sediment. Till deposited under the Antarctic Ice Sheet is notoriously difficult to penetrate due to is range of particle sizes (clay to boulder) and its high degree of consolidation from the overlying ice mass. The sediment corer has a double-wall barrel, which allows water from the top of the sediment corer to flow within the core barrel wall to the cutting shoe. This modification significantly reduces the amount of suction produced during recovery of the sediment corer without the need for an extra-heavy duty winch system to overcome the enormous suction during core recovery.

 

This is a significant technology development, intended to further Antarctic geoscience by significantly extending sedimentological sampling studies beyond the range currently accessible using piston coring and recovering sediment that rotary drilling cannot.