Microplastics are currently considered widespread marine pollutants, accumulating in sediments and shorelines around the world. Spatial distribution of microplastics in marine sediments is consequence of a combination of multiple factors (naturals and anthropics). We evaluated the drivers' factors of the abundance and distribution of two microplastics morphotypes (fibers and fragments) in surface sediments (5 cm deep) on SW Atlantic beaches with different plastics waste contribution along the coastline. Beach geomorphology, sediment grain size, distance to the urban area, continental waters discharge and human activities were the analyzed factors. Fibers abundance was significantly highest in pocket beaches, moderately exposed and closest to the urban center, while the fragments abundance was highest in beaches with stormwater outfall. The fine sand and the high recreational level were also factors driving the abundance of both morphotypes. Therefore, plastic morphotype and abundance vary according to the determining factors.

微塑料目前被认为是广泛存在的海洋污染物，在世界各地的沉积物和海岸线中积聚。海洋沉积物中微塑料的空间分布是多种因素（自然和人为因素）共同作用的结果。我们评估了大西洋西南海滩表层沉积物（5 厘米深）中两种微塑料形态类型（纤维和碎片）的丰度和分布的驱动因素，沿海岸线具有不同的塑料废物贡献。海滩地貌、沉积物粒度、距市区的距离、大陆水域流量和人类活动是分析的因素。袖珍海滩的纤维丰度显着最高，中等暴露且最靠近市中心，而碎片丰度在有雨水排放口的海滩中最高。细沙和高休闲水平也是推动两种形态类型丰富的因素。因此，塑料形态型和丰度因决定因素而异。