Comparing the transport of pristine and biofouled microplastic particles on rough surfaces

Although the occurrence of microplastic particles (MPs) and their impact on different environments have become a widely recognized research topics, their transport mechanisms in terrestrial environments are still understudied. While first research in this field have focused on the abundance of MPs in soils and its vertical distribution, only little is known about the mechanisms of MP transport on sediment and soils surfaces. This might be explained by the challenges of detecting MPs in terrestrial settings.

Therefore, we investigate the surface transport mechanisms and patterns by using fluorescent MP particles that can be tracked by an advanced complementary metal–oxide–semiconductor (CMOS) high-resolution camera. Within this study we used an experimental set-up including a flume box with surfaces of different roughness and several rates of surface discharge. We traced the pathways of environmentally pristine and biofouled fluorescent amorphously shaped Polystyrene (PS) and Polymethyl methacrylate (PMMA) to analyze how polymer type, biofilm, surface roughness and film thickness influence their transport. Subsequently, time series analysis of the images were performed and evaluated using R software. This included the calculation of particle size, estimation of pathways and path lengths. First results suggest a large influence of the water film thickness of the runoff and the surface roughness.