Measuring local levels of marine pollution by microplastics (MP) and identifying potential sources in coastal areas is essential to evaluate the associated impacts to environment and biota. The accumulation of floating MP at the sea surface is of great concern as the neustonic habitat consists of a feeding ground for primary consumers (including filter-feeders) and active predators, which makes these organisms a relevant via of MP input into the marine trophic chain. Here, a baseline evaluation of MP accumulation at the sea surface was conducted with a neuston net (335 μm mesh) at the Arrábida coastal area, in Portugal. The study site encompasses a marine protected area and an estuary, both under strong anthropogenic pressures due to multiple activities taking place. A short-term investigation on local spatiotemporal distribution, concentration and composition of MP was performed for the first time, through the monthly collection (summer 2018 to winter 2019) of samples at 6 stations. All the neuston samples contained MP and their mean concentration was 0.45 ± 0.52 items m−3 (mean ± SD). Both the averaged MP:neuston and MP:ichthyoplankton ratios were higher in December, when concentrations of organisms decreased. Temporal distribution patterns followed expected trends, as MP concentration was clearly higher in winter months due to precipitation and runoff. Although mean MP concentrations did not vary significantly between sampling stations, there was a spatial distribution of MP in relation to particle shape and size. Fragments were the most abundant shape and MP belonging to 1–2 mm size class were dominant. Amongst a diversity of 10 polymers identified by FTIR analysis, polyethylene (PE), polypropylene (PP) and copolymer PP/PE were the most abundant. Potential links between local sources/activities and the different polymers were suggested. Altogether, the information provided in this study aims to raise awareness among the identified sectors and consequently to act toward the prevention of MP inputs in the region.

中文翻译：

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葡萄牙河口和海洋公园海水表面微塑料的分布模式

测量微塑料 (MP) 造成的当地海洋污染水平并确定沿海地区的潜在来源，对于评估对环境和生物群的相关影响至关重要。由于新生态栖息地由初级消费者（包括滤食性动物）和活跃的捕食者的觅食地组成，因此海面漂浮 MP 的积累备受关注，这使得这些生物成为 MP 输入海洋营养链的相关途径. 在这里，在葡萄牙 Arrábida 沿海地区使用 Neuston 网（335 μm 网孔）对海面 MP 积累进行了基线评估。研究地点包括一个海洋保护区和一个河口，由于发生了多种活动，两者都处于强烈的人为压力之下。局部时空分布的短期调查，通过每月（2018 年夏季至 2019 年冬季）在 6 个站点的样品采集，首次对 MP 的浓度和组成进行了分析。所有neuston样品都含有MP，它们的平均浓度为0.45±0.52m-3（平均值±SD）。12 月，当生物体浓度下降时，平均 MP：neuston 和 MP：浮游鱼的比率都较高。时间分布模式遵循预期趋势，因为由于降水和径流，冬季月份 MP 浓度明显较高。尽管采样站之间的平均 MP 浓度没有显着差异，但 MP 的空间分布与颗粒形状和大小有关。碎片是最丰富的形状，属于 1-2 毫米大小等级的 MP 占主导地位。在通过 FTIR 分析确定的 10 种聚合物中，聚乙烯 (PE)、聚丙烯 (PP) 和共聚物 PP/PE 含量最高。建议了当地来源/活动与不同聚合物之间的潜在联系。总之，本研究提供的信息旨在提高已确定部门的认识，从而采取行动防止该地区的 MP 投入。