Towards microplastic hotspots detection : a comparative analysis of in-situ sampling and sea surface currents derived by HF radars

Abstract

Marine plastic pollution is a global issue with detrimental impacts on the ecosystems as well as on various aspects of human life, including health and socio-economic activities. The adverse effects of this debris have prompted the scientific community to explore new monitoring and containment approaches. In-situ sampling campaigns have been performed in various areas to quantify and characterise plastic items floating and in the water column. Due to the time and resource-intensive nature of these activities, there is a focus on integrating different approaches for marine litter monitoring. Two surveys were specifically conducted in the Siculo-Maltese platform to quantify and characterise floating microplastic debris. The collected samples underwent analysis and correlation with sea surface current data to assess the feasibility of using these currents as proxy variables for plastic occurrence mapping. In this study, high-resolution measurements of sea surface currents continuously acquired by the CALYPSO HF radar network, operating in the Sicily Channel since 2012, were taken into account. The analyses highlighted that occurrence of fragment items are inversely correlated with the total kinetic energy (r2 ~ 0.85). By applying this relation to a wider domain using Copernicus Marine Service data, high plastic accumulation areas are located at the centre of eddies often occurring in the winter period.