Analysis of sediment disturbance and plume dispersion characteristics induced by deep-sea polymetallic nodule hydraulic collectors

Environmental disturbances caused by seabed mining have garnered significant international attention. Deep-sea hydraulic mining inevitably disrupts seafloor sediments, transforming them into fine particles that remain suspended, posing long-term threats to marine ecosystems. This study systematically investigates sediment disturbance characteristics under varying jet parameters through model experiments, aiming to assess the environmental impact of jetting operations and optimize jet parameters. The jet parameters investigated include jet velocity, target distance, and nozzle height. Results indicate that seabed disturbance process can be divided into three stages: critical suspension, critical erosion, and plume dispersion. Seabed morphology exhibits distinct V-shaped or U-shaped features, with target-to-nozzle height ratios (B/H) equals to 1 identified as the critical threshold for shape transition. Plume transformation rate increases with jet velocity, ranging from 15% to 55%. After disturbance, the plume suspended concentration decreases with increasing nozzle height, reaching a maximum reduction of up to 70%. These findings provide valuable data for minimizing environmental disturbance in deep-sea jetting operations. Based on experimental results, a new method for calculating the relationship between jet parameters and plume dispersion is proposed, offering a theoretical and technical basis for reducing environmental impact in deep-sea mining.