Towards Underwater Macroplastic Monitoring Using Echo Sounding

Plastics originating from land are mainly transported to the oceans by rivers. The total plastic transport seas remains uncertain because of difficulties in measuring and lack standard observation techniques. A large focus observations is on plastics floating water surface. However, an increasing number suggest that quantities suspension, below Available underwater monitoring methods use nets or fish traps need be deployed surface labor-intensive. In this research, we explore echo sounding as innovative low-cost method quantify identify suspended macroplastics. Experiments under controlled natural conditions using a off-the-shelf device show items can detected identified up 7 m river Eight different debris (metal can, cup, bottles, food wrappers, container) were characterized based their reflection signature. Reflectance diverged significantly organic material non-plastic anthropogenic debris. During multi-day trial field expedition Guadalete river, Spain, found between 0.8 6.3 depth considerable transported. As most removal strategies upper layer (up approximately 1.5 depth), substantial share may neglected. With paper 1) demonstrate promising tool for monitoring, 2) emphasize importance improved understanding existing loads