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Tracking Microplastics Across the Streambed Interface: Using Laser‐Induced‐Fluorescence to Quantitatively Analyze Microplastic Transport in an Experimental Flume
Author(s) -
Boos JanPascal,
Gilfedder Benjamin Silas,
Frei Sven
Publication year - 2021
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2021wr031064
Subject(s) - flume , microplastics , advection , environmental science , geology , hydrology (agriculture) , soil science , geotechnical engineering , flow (mathematics) , mechanics , oceanography , physics , thermodynamics
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 MPs transport and retention mechanisms in fluvial systems remain poorly understood. As part of this technical note, we present a novel method for a quantitative analysis of the spatiotemporal transport and retention of pore‐scale MPs in an experimental flume. A continuous mass balance for MPs in surface water was achieved using two online fluorometers, while a laser‐induced Fluorescence‐Imaging‐System was developed to track and quantify the spatial migration of MPs through the streambed sediments. The detection limit was <1 μg/L for 1 μm polystyrene microbeads with the fluorometers and 3 μg/L for the Fluorescence‐Imaging‐System. The system was able to quantitatively track the advective transfer of MPs into the streambed sediments: a process that has yet not been observed experimentally. Results showed that MPs infiltrated into the streambed sediments up to a depth twice the bedform amplitude. This work provides a novel experimental method to quantitatively monitor MP transport through porous media and advective exchange of MP across the streambed interface.