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The effects of large roughness elements on the in-stream transport and retention of polystyrene microplastics

Scientific Reports 2023 8 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count. Score: 40 ? 0–100 AI score estimating relevance to the microplastics field. Papers below 30 are filtered from public browse.

Usama Ijaz, Usama Ijaz, Usama Ijaz, Usama Ijaz, Usama Ijaz, Usama Ijaz, Usama Ijaz, Usama Ijaz, Usama Ijaz, Usama Ijaz, Abul B. M. Baki Wenming Zhang, Wenming Zhang, Abul B. M. Baki Abul B. M. Baki Wenming Zhang, Abul B. M. Baki Abul B. M. Baki Abul B. M. Baki Abul B. M. Baki Abul B. M. Baki Wenming Zhang, Wenming Zhang, Wenming Zhang, Wenming Zhang, Wenming Zhang, Wenming Zhang, Omar I. Abdul‐Aziz, Omar I. Abdul‐Aziz, Wenming Zhang, Abul B. M. Baki Abul B. M. Baki Wenming Zhang, Abul B. M. Baki Abul B. M. Baki Abul B. M. Baki Abul B. M. Baki Wenming Zhang, Wenming Zhang, Abul B. M. Baki Wenming Zhang, Abul B. M. Baki Wenming Zhang, Wenming Zhang, Alan D. Christian, Alan D. Christian, Alan D. Christian, Abul B. M. Baki Wenming Zhang, Wenming Zhang, Wenming Zhang, Wenming Zhang, Abul B. M. Baki Abul B. M. Baki

Summary

Laboratory flume experiments showed that large roughness elements like boulders in riverbeds significantly alter how polystyrene microplastics are transported and retained, with two distinct flow regimes determining whether particles travel quickly or get trapped. Understanding these river dynamics is essential for predicting where microplastics accumulate in freshwater systems and designing realistic environmental risk models.

Polymers

The mechanisms controlling transport and retention of microplastics (MPs) in riverine systems are not understood well. We investigated the impact of large roughness elements (LREs) on in-stream transport and retention of the ubiquitous polystyrene-microplastics (PS-MPs). Scaled experiments were conducted with and without LREs under various shear Reynolds numbers (Re*) in an ecohydraulics flume. Our results, for the first time, demonstrated a clear dependence of the MPs' velocity on Re* in LREs-dominated channel. Two distinct regimes and thresholds were identified: lower Re* (≤ 15,000) regime corresponding to higher velocities of MPs ([Formula: see text]> 0.45), and higher Re* (> 15,000) to lower [Formula: see text]< 0.45). The presence and higher density of LREs increased Re*, decreased [Formula: see text], and enhanced the PS-MPs capture. The LREs-generated turbulence kinetic energy (TKE) was found to be a good predictor of PS-MPs transport and retention rates, indicating the effectiveness of LREs in retaining PS-MPs in streams and rivers.

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