Plastic pollution originates from human activities, with urban environments acting as hotspots. However, little is known about how litter, including plastic, enters the water cycle and this limits the prediction of pollution hydrographs.

In this project, we aim to study the incipient motion of the five most common types of litter, based on recent scientific literature. These may comprehend soft and hard plastic fragments, films and cigarette butts, among others. The primary goal of this project is to establish generalised relationships, based on rainfall intensity and street runoff (i.e., depth and velocity) that can predict at which point of a storm litter gets mobilised and transported in the direction of the urban drainage system. A secondary goal of this project is to describe the dynamics of the early movement of litter, which can range from intermittent tumbling movement over the street-floor (filling and emptying with water, potentially) to, rather differently, completely floating, or surfing over the runoff layer. A third goal of this study is to conduct a preliminary set of tests where incipient motion of microplastics (e.g., car tire particles) are studied. This is specially complicated methodologically.

The goal is to obtain water samples for different levels of rainfall and runoff that can later be used to study analytical methods to describe mass fraction of microplastics and use this knowledge to prepare a future, better targeted research project (potentially with the host institution). All these experiments will be conducted in the BLOCK facility of the University of A Coruña (UDC).