Abundance and composition of floating microplastics in the central-western Mediterranean Sea

74 neuston samples were collected during two consecutive cruises carried out in the Mediterranean Sea between May and June 2013 (Fig. 1). Samples were all collected using a 200 μm Neuston net which was towed for ~ 5 minutes at a speed of 1.5-2 knots. Samples were fixed with 80% EtOH and stored for laboratory analysis. A mechanical flowmeter was used to measure the trawl length. In the laboratory, samples were sorted at the stereomicroscope. All plastic particles were hand-picked using laboratory tweezers and separated into seven size classes by sequential sieving through a series of stacked stainless steel meshes. All particles in each size category were counted, dried, weighed on an electronic balance and classified according to 5 shape and 7 colour categories. Because of the high risk of air-borne contamination, all synthetic fibres were subsequently excluded from density calculations.