Van Veen Grab Sampler
The Van Veen Grab Sampler is an instrument to sample sediment in water environments. Usually it is a clamshell bucket made out of stainless steel. Up to 20 cm deep samples of roughly 0.1 m2 can be extracted with this instrument. It can be light-weight (roughly 5 kg) and low-tech. The smallest version even fits into hand luggage.
A draw-back of the use of this sampler is that it tends to disturb the sediments more than a box corer does.
While letting the instrument down into the water, the two levers with buckets at their ends are spread like an open scissor. The levers are locked in this position, and unlock when hitting the ground. When the rope is pulled upward again, the two buckets close and grab a sample from the sea floor.
Van Veen Grab when it is locked, ready to be lowered to the floor
It is now unlocked after hitting the floor, ready to collect sediment
When lifting it after unlocked, the jaws will close to collect sediment inside
Three small technical changes lead to variations with more mechanical parts or structure:
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Wikipedia