Tracking Microplastics Across the Streambed Interface: Using Laser‐Induced‐Fluorescence to Quantitatively Analyze Microplastic Transport in an Experimental Flume

Rivers and streams are a primary transport vector for microplastics (MPs), connecting terrestrial sources to marine environments. While previous studies indicated that pore-scale MPs can accumulate in streambed sediments, the specific retention mechanisms fluvial systems remain poorly understood. As part of this technical note, we present novel method quantitative analysis spatiotemporal an experimental flume. A continuous mass balance surface water was achieved using two online fluorometers, while laser-induced Fluorescence-Imaging-System developed track quantify spatial migration through sediments. The detection limit <1 μg/L 1 μm polystyrene microbeads with fluorometers 3 Fluorescence-Imaging-System. system able quantitatively advective transfer into sediments: process has yet not been observed experimentally. Results showed infiltrated sediments up depth twice bedform amplitude. This work provides monitor MP porous media exchange across interface.