The reported microplastic (MP) levels in the surface waters of our rivers, estuaries, and oceans span several orders of magnitude. However, the inter-comparison of these values is constrained by a lack of harmonization of the methods for sampling, extracting, and identifying these pollutants. Typically, nets are used for sampling floating MPs, limiting their quantification to the mesh size, predominantly 333 µm. Consequently, the presence of smaller MPs has mainly been overlooked, leading to underestimating their presence in aquatic environments. Distribution models and scarce in-situ observations suggest that MP concentrations and particle size decrease along the first meters of the water column. In this study, we investigate the MP vertical distribution using a novel filtration device to sample MPs (>10 µm) in the air-surface interface and subsurface waters (5 m depth) simultaneously. During a JPI-Ocean FACTS cruise, sampling stations were selected following a gradient from high anthropogenic pressure areas to remote ones in the Byfjorden (Norway). MPs were extracted following a multi-step treatment, analyzed using state-of-the-art µFT-IR spectroscopy, and systematically identified using the software siMPle as well as pyr-GC/MS  to quantify Tire Wear Particles (TWPs) content. Our findings contribute to understanding the dispersion of small MPs in the upper water column, providing crucial insights into the role of size- and polymer-dependent mechanisms influencing their vertical transport.

Primary Presenter: Laura Simon-Sanchez, Aalborg University (lasisa@build.aau.dk)

Authors:

Laura Simon-Sánchez, Department of the Built Environment, Aalborg University  (lasisa@build.aau.dk)

Alvise Vianello, Department of the Built Environment, Aalborg University  (avia@build.aau.dk)

Ashani Arulananthan, Department of the Built Environment, Aalborg University  (ashaarul@build.aau.dk)

Claudia Lorenz, Department of the Built Environment, Aalborg University  (clo@build.aau.dk)

Jes Vollertsen, Department of the Built Environment, Aalborg University  (jesvollertsen@build.aau.dk)

Adrián Jaén-Gil, NORCE, Norwegian Research Centre AS  (adja@norceresearch.no)

Alessio Gomiero, NORCE, Norwegian Research Centre AS  (algo@norceresearch.no)