Microplastic Pollution in Benthic Midstream Sediments of the Rhine River
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- Text
- Journal contribution
- Evolutionary Biology
- Ecology
- Inorganic Chemistry
- Environmental Sciences not elsewhere classified
- Biological Sciences not elsewhere classified
- Chemical Sciences not elsewhere classified
- MP concentrations
- FTIR
- Rhine River Rivers
- MP numbers
- Rhine River
- near-surface compartments
- fluvial environment
- Microplastic Pollution
- transport vectors
- open-flowing stretches
- midstream sediments
- riverbed sediment aliquots
- selection bias
- state-of-the art
- riverbed access
- Benthic Midstream Sediments