Wear and tear from tyres significantly contributes to the flow of (micro-)plastics into the environment. This paper compiles the fragmented knowledge on tyre wear and tear characteristics, amounts of particles emitted, pathways in the environment, and the possible effects on humans. The estimated per capita emission ranges from 0.23 to 4.7 kg/year, with a global average of 0.81 kg/year. The emissions from car tyres (100%) are substantially higher than those of other sources of microplastics, e.g., airplane tyres (2%), artificial turf (12–50%), brake wear (8%) and road markings (5%). Emissions and pathways depend on local factors like road type or sewage systems. The relative contribution of tyre wear and tear to the total global amount of plastics ending up in our oceans is estimated to be 5–10%. In air, 3–7% of the particulate matter (PM_2.5) is estimated to consist of tyre wear and tear, indicating that it may contribute to the global health burden of air pollution which has been projected by the World Health Organization (WHO) at 3 million deaths in 2012. The wear and tear also enters our food chain, but further research is needed to assess human health risks. It is concluded here that tyre wear and tear is a stealthy source of microplastics in our environment, which can only be addressed effectively if awareness increases, knowledge gaps on quantities and effects are being closed, and creative technical solutions are being sought. This requires a global effort from all stakeholders; consumers, regulators, industry and researchers alike.

Plastic pollution in aquatic ecosystems is a growing threat to ecosystem health and human livelihood. Recent studies show that the majority of environmental plastics accumulate within river systems for years, decades and potentially even longer. Long‐term and system‐scale observations are key to improve the understanding of transport and retention dynamics, to identify sources and sinks, and to assess potential risks. The goal of this study was to quantify and explain the variation in floating plastic transport in the Rhine‐Meuse delta, using a novel 1‐year observational data set. We found a strong positive correlations between floating plastic transport and discharge. During peak discharge events, plastic transport was found up to six times higher than under normal conditions. Plastic transport varied up to a factor four along the Rhine and Meuse rivers, which is hypothesized to be related to the complex river network, locations of urban areas, and tidal dynamics. Altogether, our findings demonstrate the important role of hydrology as driving force of plastic transport dynamics. Our study emphasizes the need for exploring other factors that may explain the spatiotemporal variation in floating plastic transport. The world's most polluted rivers are connected to the ocean through complex deltas. Providing reliable observations and data‐driven insights in the transport and dynamics are key to optimize plastic pollution prevention and reduction strategies. With our paper we aim to contribute to both advancing the fundamental understanding of plastic transport dynamics, and the establishment of long‐term and harmonized data collection at the river basin scale.

The potential and scale of cities enable economic growth and the improvement of citizens’ access to jobs, education, healthcare, culture, public utilities and services. Solid waste management (SWM) is one of the key services provided by cities. Its operations are complex, very visible to the general public, and impacted by strong financial, societal, and political constraints. Performances in developing countries, however, are not positive. United Nations research shows urban collection services covering no more than 39% of the population in low-income countries. Why are many cities in developing countries not able to use their increasing wealth and scale for basic SWM services such as city cleaning, collection, and sustainable landfilling? This paper provides a review of literature on this question over the last decade. It shows that research is mostly on symptoms and has not led to a deeper diagnosis of causes. Lack of resources, infrastructure, awareness, and institutional strength are often pinpointed as causes but, in fact, they should be addressed as symptoms. These symptoms should be designated as dependent variables in a complex causal network with systemic feedbacks, hindering or neutralizing attempts to improve performances if not properly dealt with. Research should concentrate more on assessing the relations between urbanization, urban processes, and urban governance that shape the performance of urban solid waste management. System dynamics modeling may provide new approaches for this diagnosis.

Various studies advocate training students prior to a peer-feedback activity to ensure high quality of feedback. Next to investing in students’ peer-feedback skills, it is important to focus on the underlying perceptions since perceptions influence learning behavior. We implemented an online peer-feedback training session in a massive open online course and examined students’ perceptions of peer-feedback and training focusing on their willingness, perceived usefulness, perceived preparedness, and general attitude; and students’ peer-feedback experience and its relation to their perception. Analysis of a perception survey from 259 students revealed that the amount of prior experience results in significant differences in students’ perception. Students without prior peer-feedback experience scored higher on willingness, usefulness, preparedness, and general attitude compared to students with some prior experience. Those with a lot of experience showed the strongest positive perception scores. No significant differences for the effect of training on perception could be measured with the available data.

Rivers play an important role in the macroplastics transport and retention dynamics in the environment. Therefore, gaining an understanding of these processes is vital in order to help determine the fate of macroplastic in the environment. During flood events the transport of floating macroplastic is known to increase. We compared plastic accumulation and flushing on sixteen riverbanks along the Dutch Meuse river during the period that includes the July 2021 extreme flood to plastic accumulation on the same riverbanks as during normal discharge conditions between 2018 and 2021. Here we show that following the flood small macroplastic categories ( < 2.5 cm) were flushed from the riverbanks, while larger soft plastic fragments (2.5–50 cm) and wet tissues were deposited. We found that for all plastic categories and for all riverbanks averaged, the plastic accumulation rate during the July 2021 flood was higher than that which would be expected for that time of year. However, the average accumulation rate for all locations during the period that included the flood was lower than the average accumulation rate over the Dutch winter (Oct/Nov–Feb/Mar). Our results show that litter category composition following the July 2021 flood differed from normal conditions. This indicates that plastic deposition and remobilization processes on riverbanks differ between extreme flood and annually average conditions. These observations contribute to a better understanding of the fate of macroplastic in the environment in terms of the drivers of both its transport and deposition.

Mismanaged plastic waste (MPW) and urban flooding are typically considered distinct environmental challenges. However, there are notable links between growing quantities of MPW and the rising incidence of floods in cities. A majority of people now live in cities, especially along coastlines and in estuaries where residents are both vulnerable to flooding and significant sources of plastic waste. Predicted increases in the frequency and severity of heavy rainfall associated with anthropogenic climate change coincide with rising global quantities of MPW, much of which is discharged into water bodies and the sea. Given the urgent and expanding nature of these issues, understanding impacts of urban floods on solid waste management and vice versa is crucial. Social‐ecological systems (SES) thinking calls for a holistic approach to the relationships and interactions between human actors and environmental systems which can result in dynamic and emergent outcomes. In this review paper, we make a first step towards better understanding of the interactions between urban flooding and MPW by synthesizing emerging quantitative and qualitative research on particular aspects of such interactions. More research is needed which explicitly focuses on and elaborates the nature of these interactions, and also to consider potential relations across scales (from global to local) and over both long and short timeframes. We conclude that an SES approach can make visible novel possibilities for interventions which are context specific and sensitive to the interactions between urban floods and MPW.This article is categorized under: Science of Water > Water and Environmental Change Human Water > Water Governance Engineering Water > Planning Water