Abstract
Rivers are major transport vectors for microplastics (MP) toward the sea. However, there is evidence that MP can temporarily or permanently be inhibited from migrating downstream by retention in sediments or ingestion by organisms. MP concentrations, compositions, and fate within the different compartments of the fluvial environment are poorly understood. Here, benthic, midstream sediments of two undammed, open-flowing stretches were investigated in the Rhine River, one of the world's busiest inland waterways. Twenty-five samples were collected at ten sites via riverbed access through a diving bell or dredging. We performed the first comprehensive analysis of riverbed sediment aliquots that avoids visual selection bias using state-of-the art automated micro-Fourier-transform infrared spectroscopy (μFTIR) imaging. MP numbers ranged between 0.26 ± 0.01 and 11.07 ± 0.6 × 103 MP kg-1 while MP particles <75 μm accounted for a mean numerical proportion ± SD of 96 ± 6%. MP concentrations decreased with sediment depth. Eighteen polymers were identified in the size range of 11-500 μm; the acrylates/polyurethane/varnish (APV) cluster was found at all sites (mean numerical proportion, 70 ± 19%), possibly indicating particulate pollution from ship antifouling paint. Overall, polymers denser than freshwater (>1 g cm-3) dominated (85 ± 18%), which contrasts the large proportions of low-density polymers previously reported in near-surface compartments of the Rhine.
| Original language | English |
|---|---|
| Journal | Environmental Science and Technology |
| Volume | 53 |
| Issue number | 10 |
| Pages (from-to) | 6053-6062 |
| Number of pages | 10 |
| ISSN | 0013-936X |
| DOIs | |
| Publication status | Published - 21 May 2019 |
| Externally published | Yes |
Bibliographical note
Funding Information:We thank the waterways and shipping administrations (WSA) Duisburg-Rhein and Bingen, Germany for vessel access and technical support. We also thank Nicole Seiler-Kurth, Heidi Schiffer and Hedwig Maria Scharlipp, MGU University of Basel, as well as Vanessa Wirzberger, AWI Helgoland, for laboratory assistance. Special thanks go to Andrea Devlin, chief editor of Science Editing Experts for proof reading and language support. This work was supported by the World Wide Fund for Nature (WWF) Switzerland and the German Federal Ministry of Education and Research (Project BASEMAN - Defining the baselines and standards for microplastics analyses in European waters; BMBF grant 03F0734A). C.L. thanks the Deutsche Bundesstiftung Umwelt (DBU) for financial support.
Publisher Copyright:
© 2019 American Chemical Society.