Assessment of microplastic pollution in sand beach from SW Atlantic coast (Argentina) using a regional harmonized method.

Argentina ranks among the Latin American countries with the highest per capita plastic consumption, producing 1,162,000 tons annually and importing an additional 882,600 tons. This high level of consumption leads to the accumulation of plastic waste in both terrestrial and aquatic environments. The environmental assessment of plastic debris pollution is essential for identifying the sources and fate of these particles. Microplastics (MPs; particles <5 mm) cause a great environmental concern due to their potential ecological impacts and increased capacity for transport within ecosystems. Nevertheless, the lack of standardized methodologies for their quantification presents a significant challenge in accurately assessing their regional and local pollution status. This work, reports the occurrence and characteristics of MPs in sand beach  along the main coastal city of Argentina (Mar del Plata city)  and surrounding areas using a harmonized methodology implemented by the regional network REMARCO (Research Network of Marine-Coastal Stressors in Latin America and the Caribbean). The used protocol is supported by the 18 member states of the network. Samples were obtained in five different beaches from south to north along 50 km of the coast and differing in their anthropic impact. After MPs extraction from the 0.3-1 mm and 1-5 mm fractions, the polymer was confirmed by its spectroscopic characterization using Fourier-Transform Infrared spectroscopy (FTIR-ATR). The total abundances of MPs (mean ± std. dev; 1-5 mm) in beach sand ranged from 00 ± 00 to 966 ± 1169 items per m². Primary and secondary MPs were observed, contributing 7-23% and 77-93 % of the total amount, respectively. Six polymers were identified: ethylene vinyl acetate (EVA), polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polyurethane (PU). PS particles predominated across all beach sand, contributing between 54% and 86% of the total particles analyzed. The results show a differentiated impact among local beaches in terms of MPs abundance, with higher values in beach sand under the influence of urban runoff discharges. The PS dominance highlights the intensive use of products derived from this polymer in the studied area. This information is crucial for guiding future control and management plans aimed at reducing marine plastic pollution. Founding. ANPCyT Argentina PICT 2021-0060; IAEA: RLA-7025; RLA-7028; INT-7021,CRP-K41024-26933.