Deep-Sea ROV Mounted Niskin Arrays Contribute to Sediment Plume Monitoring

Ocean Scientific International Ltd (OSIL) have released a dedicated deep-sea turbidity and water quality monitoring system for remotely operated underwater vehicles (ROV) and subsea vehicles to aid with the accurate modeling of sediment plumes and their wider impact.

Certain deep-sea activities such as the collection of polymetallic nodules can generate large sediment plumes that affect the entire marine environment (seabed, water column and marine organisms) over great distances, and The International Seabed Authority (ISA) is shortly due to finalize “The Mining Code”, which will provide a comprehensive set of rules, regulations and procedures issued by ISA to regulate prospecting, exploration and exploitation of marine minerals in the international seabed area, to manage these activities and minimize their impact.

The OSIL ROV Niskin Array uniquely combines an array of five individually triggered Niskin bottles with high accuracy turbidity and water quality sensors to provide real time data and water samples on demand, in addition to feedback on the system status, enabling user to quantify the sediment plume scale and density. The Niskin bottles are fired independently by a new system designed and developed by OSIL, utilizing addressable solenoid actuators.

The innovative software-controlled system allows for a seamless interface with the client vehicle carrying the array, while the thin-walled solenoid housings themselves are oil filled, with a pressure compensation system ensuring that they can accommodate the range of changes in pressure and temperature experienced from sampling in the deep sea to deck setup in warmer climates.

The modular stackable arrays can be daisy chained together to create a larger network if required, and are rated to 6000m. The information gathered helps to improve our understanding of the ecological and environmental impacts of deep-sea activities, which leads to better informed management decisions and regulations surrounding these activities.