Understanding acoustic backscatters from underwater plastic items in controlled and semi-controlled environments

The ever-increasing production of plastics, including single use items, has led to enormous amounts of pollution, threatening ecosystems, livelihoods, safety and human health. Rivers are important pathways for transporting plastic waste to the oceans.

Recent studies show that a substantial proportion of plastics is transported and retained below the water surface. Despite advances in monitoring technologies, current approaches focus mainly on counting or removing floating and deposited plastics, using visual counts, citizen science, drones, cameras, or GPS trackers. Leading to costly, labor-intensive, and environmentally invasive work.

Quantifying the full plastic transport behavior in the water column remains challenging, resulting in a lack of information on cross-sectional plastic flux. Our project aims to detect underwater riverine macroplastic pollution (>5 mm) using a multifrequency Acoustic Doppler Current Profiler (ADCP). While acoustic measurements show promise for plastic detection (Boon et al., 2023), a comprehensive understanding of how backscatter varies with item characteristics (size, shape, composition, and orientation) under different environmental conditions is still missing.

In this poster presentation, we will discuss the first results of using an echo sounder to detect plastics (PET, PP, PS) and other materials (e.g. paper, organic material and aluminum) in controlled and semi-controlled environments. We will present the first backscatter signatures from different polymer types and outline future approaches.

We anticipate that our results have the potential to provide continuous and cross-sectional estimates of underwater plastic transport in rivers. By providing insights into the impact of plastic pollution interventions and enabling accurate identification of underwater plastic behavior, this approach could support more effective mitigation and remediation efforts.