Previous studies of uptake and effects of nanoplastics by marine organisms have been conducted at what may be unrealistically high concentrations. This is a consequence of the analytical challenges in tracking plastic particles in organisms at environmentally relevant concentrations and highlights the need for new approaches. Here, we present pulse exposures of 14C-radiolabeled nanopolystyrene to a commercially important mollusk, Pecten maximus, at what have been predicted to be environmentally relevant concentrations (<15 μg L–1). Uptake was rapid and was greater for 24 nm than for 250 nm particles. After 6 h, autoradiography showed accumulation of 250 nm nanoplastics in the intestine, while 24 nm particles were dispersed throughout the whole-body, possibly indicating some translocation across epithelial membranes. However, depuration was also relatively rapid for both sizes; 24 nm particles were no longer detectable after 14 days, although some 250 nm particles were still detectable after 48 days. Particle size thus apparently influenced the biokinetics and suggests a need for chronic exposure studies. Modeling extrapolations indicated that it could take 300 days of continued environmental exposure for uptake to reach equilibrium in scallop body tissues although the concentrations would still below 2.7 mg g–1. Comparison with previous work in which scallops were exposed to nonplastic (silver) nanomaterials of similar size (20 nm), suggests that nanoparticle composition may also influence the uptake tissue distributions somewhat.

Owing to their physical and chemical properties, particles generated by the abrasion of tyre tread against road surfaces, or tyre wear particles, are recognised as microplastics. Recent desk-based studies suggest tyre wear to be a major contributor of microplastic emissions to the environment. This study aimed to quantify tyre wear in roadside drains and the natural environment near to a major road intersection. Tyre particles were identified by visual identification and a subsample confirmed as tyre wear by GC-MS using Ncyclohexyl-2-benzothiazolamine (NCBA) as a marker. The abundance of tyre wear within roadside drains was greater in areas associated with increased braking and accelerating than high traffic densities (p = <0.05). Tyre particle abundance in the natural environment ranged from 0.6±0.33 to 65±7.36 in 5 mL of material, with some evidence of decline with distance from the road. This study offers preliminary data regarding the generation and abundance of this under-researched microplastic.

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International audienceSoils in riparian wetlands are periodically flooded, resulting in the establishment of reducing conditions and the solubilization of As, subsequently to the reductive dissolution of Fe(III)-oxyhydroxides. When the water level decreases, the wetlands are reoxidized. However, although the behavior of As under the reducing period is well documented, there is a lack of information regarding its behavior during the oxidizing period.In this study, we investigated As speciation in oxidation products from an initially reduced wetland soil solution recovered from the Naizin-Kervidy riparian wetland (France). The oxidation products were studied using NanoSIMS analysis and synchrotron X-ray techniques. These products were enriched in organic carbon, Fe and As compared with the soil and soil solution. The NanoSIMS analysis showed a colocalization of As and Fe but also revealed the presence of As hotspots where As was either associated with Fe or organic matter (OM). X-ray absorption spectroscopy (XAS) showed that As was sorbed to Fe(III)-oxyhydroxides. The linear combination fitting (LCF) of the As K-edge XANES revealed that As was not totally oxidized (i.e. between 65 and 100% of As(V)). Shell-by-shell fits of the As K-edge EXAFS showed that As formed binuclear edge-sharing 2E (RAs-Fe = 2.74–2.95 Å) and corner-sharing 2C (RAs-Fe = 3.28–3.43 Å) complexes with Fe.In addition to study of natural samples, oxidized reference samples were analyzed and demonstrated the role of OM on As speciation. The persistence of As(III) was explained by OM control on the As carrying phase during the oxidation, via the formation of nano-lepidocrocite and small Fe-clusters bound to OM. The small size of the Fe phase led to an increased capacity for As adsorption and an increase in 2E sites compared to 2C active sites for As(III) oxidation