**4. Distribution of microplastics in the marine environment**

Plastic contamination and microplastics have spread throughout the world's aquatic ecosystems [21, 22, 31]. Plastic pollution and microplastics can be transported over long distances by ocean currents, winds, river outflow, and drift [19, 45, 46],


#### **Table 1.**

*Classification of microplastic, source of transport, and type of marine environment found.*

including mid-ocean islands [42], poles[47], and ocean depths [31]. Pellets are lost during loading and transit, both on land and at sea, as well as during processing at plastic molding plants. Because of their lightness and durability, lost pellets can travel long miles in the ocean before being stranded, either temporarily or permanently [42]. While plastic litter can be found across the whole of the marine ecosystem, the distribution of this debris and microplastics varies in type and nature [16, 46]. Beached litter descriptions frequently mention a variety of plastic manufacture pellets (**Table 1**) [57].
