Autonomous, submersible sediment sampler for retrieval of radioactive particles

Seabed sediment sampling, in addition to its utility in marine scientific research, can uncover the extent of anthropogenic contamination in bodies of water. For example, the technique can be used for the retrieval of radioactive particles where contamination was suspected to occur after incidents like the Fukushima nuclear disaster.

Hunt and Joyce report on a prototype autonomous sediment sampler that is uniquely tailored to the collection of radioactivity originating from nuclear facilities. They were motivated to build something that could retrieve samples from the seabed without putting human divers at risk, would be compatible with off-the-shelf remotely operated vehicles (ROVs), and could record the location of the retrieval.

The autonomous subsea multi-sampler can recover sediment samples from two different locations in a single deployment. It is free-standing and can either be used as a stand-alone device or with an exemplar ROV. It contains an internal GPS data logger to record the precise time and initial location at which a sample is taken.

“The mechanism is triggered by contacting a submerged surface replicating the seabed, picks up a small vessel designed to also act as a scoop, collects a sample, and stores it, along with the GPS data,” said author Malcolm Joyce. “This combination of capabilities is its unique attribute.”

The researchers tested the multi-sampler by assessing both the collection cycle and sample collection pattern in a laboratory-based mock-up of a sandy, flooded testbed. The device performed repeated, submerged deployments without error, and the collected sediment appeared satisfactory in pattern, quality, and initial position.

“The next step would be field tests with an ROV to confirm its resilience in shallow sea water,” said Joyce.

Source: “A GPS-enabled seabed sediment sampler: Recovery efficiency and efficacy,” by W. J. Hunt and M. J. Joyce, Review of Scientific Instruments (2022). The article can be accessed at http://doi.org/10.1063/5.0077269 .