To address the lack of long-term continuous monitoring methods for evaluating the impact of deep-sea polymetallic nodule mining on the near-bottom (with height less than 1 m above the seafloor) ecological environment, a novel near-bottom long-term monitoring platform has been designed and developed. It adopts a passive self-righting design by a "upward-buoyancy and downward-gravity", and has solved the problem of uncontrolled landing attitude during untethered deployment. A novel "sleep-wake" intermittent working mode was proposed to achieve long-term continuous monitoring under limited battery capacity. Deep-sea tests were successfully completed in Block A-5 of the Eastern Pacific. The at-sea test results show that the platform maintained a stable landing attitude and successfully acquired the pH value (average 7.50), flow velocity (average 0.003 3 m/s), and turbidity (1.17-1.25 FTU) of the near-bottom seawater during the testing period, verifying the reliability and effectiveness of the platform in the extreme deep-sea environment.

deep-sea mining  /  environmental monitoring  /  monitoring device  /  monitoring platform  /  near-bottom monitoring  /  self-righting structure  /  low power consumption  /  in-situ observation  /  sea trial  /  hydrological parameter