The samples were later rinsed in salt water, which floated most of the plastic to the surface for removal. Using a dissecting microscope, plastic was removed from preserved natural material, and then sorted by rinsing through Tyler sieves into six size classes: 0.355–0.499 mm, 0.500–0.709 mm, 0.710–0.999 mm, 1.00–2.79 mm, 2.80–4.749 mm, >4.75 mm. Individual pieces of plastic were divided into categories; fragment, polystyrene fragment, pellet, polypropylene/monofilament line, film; and then counted. The area sampled was calculated

by using onboard knotmeter data to measure the actual length of sea surface trawled in the 60-min period. The tow length multiplied by the width of the trawl provided the area sampled, allowing particle weight and abundance per km2 to be calculated. Using the Beaufort Scale (Beer, 1996), the sea state was calculated using wave height observed by three crewmembers and decided selleck chemicals by consensus. Forty six out of 48 net tows (96%) contained plastic marine pollution, with no plastic found in two of the eastern-most samples (Fig. 1). Fig. 1 shows excellent correspondence between tracer distribution assessed by the model (shaded gray areas) and the observed count of plastic particles (color dots). For the comparisons in Fig. 2 and Fig. 3, the model has been scaled using the integral

values, summed over all stations. Visual evaluation shows good correspondence between the observations (bars in Fig. 2 and Fig. 3) and the model (solid lines), all demonstrating Selleckchem AUY922 bell-shape distributions along the

transect. Correlation coefficients were found equal to 0.45 and 0.44, respectively. Somewhat wider model “bells” and their southeastern shift by a few stations may be due the difference between the multi-year mean, assessed by the model, and quasi-instantaneous state of the system, sampled during the 2 months of the expedition. The average abundance was 26,898 pieces km−2, and the average weight was 70.96 g km−2. 85.6% of the total count and 88.8% of the total weight were collected between 97°09′W (sample 17) and 111°91′W (sample 32), representing the center third of the sampling transect (Fig. 2 and Fig. 3). Plastic particles were found in each of the six size classes, and of the five type categories all were found except for foam, which did not occur in any of the 48 samples (Table 1). The two size classes representing particles 1.00–4.749 mm 3-mercaptopyruvate sulfurtransferase accounted for 55% of the total particle count and 72% of the total weight (Table 1). Plastic fragments by far dominated the microplastics collected in this study, both by count and by weight. Pellets were found in relatively low abundances, but due to their large individual weight made up 9.6% of the total microplastics weight. Lines and thin films were relatively abundant, but constituted less weight than the pellets. As shown in Fig. 2 and Fig. 3, the sample 22, collected at 29°04′S, 101°73′W, contained 1102 pieces and a total weight of 2.