Fig. 7From: Tracing the horizontal transport of microplastics on rough surfacesRunoff stained with Nile red. a: coarse surface irrigated at 7.5∘ inclination with 7.2 L h −1; b: fine surface irrigated at 2.5∘ inclination with 7.2 L h −1. Preferential flow paths are visible on the fine surfaceBack to article page