Urban water systems as entry points for river plastic pollution

Abstract

<p>Accumulation of plastic in aquatic environments negatively impacts ecosystems and human livelihood. Urban areas are assumed to the main source of plastic pollution in these environments, because of high anthropogenic activity. Yet, the drivers of plastic emissions, abundance and retention within these systems and subsequent transport to river systems is poorly understood. In this study, we demonstrate that urban water systems function as major contributors to river plastic pollution, and explore the potential driving factors contributing to the transport dynamics. Monthly visual counting of floating litter at six outlets of the Amsterdam water system results in an estimated 2.7 million items to enter the closely connected IJ river annually, ranking it among the most polluting systems measured in the Netherlands and Europe. Subsequent analyses of environmental drivers (including rainfall, sunlight, wind speed and tidal regimes) and litter flux showed no strong correlations (r = -0.19 - 0.16), implying additional investigation of potential drivers is required. High frequency observations at various locations within the urban water system and advanced monitoring using novel technologies could be explored to harmonize and automate monitoring. Once litter type and abundance are well-defined with a clear origin, communication of the results with local communities and stakeholders could help co-develop solutions and stimulate behavioural change geared to reduce plastic pollution in urban environments.</p>

Large variation in Mekong river plastic transport between wet and dry season

“…The mass balance suggests that during the wet season, even more plastic enters the river system from Phnom Penh (Haberstroh et al, 2021a). Also in other urban areas connected to natural river it has been found that during periods of increased rainfall and discharge, more plastic are mobilized and transported into rivers (Tasseron et al, 2022;Treilles et al, 2022). To better quantify and understand sources of riverine plastic, also the seasonality of entry processes should be considered.…”

The impact of floods on plastic pollution

“…Research on such travel dynamics in urban areas remains scarce. A recent study on Amsterdam found no significant correlations between rainfall and floating plastic transport in either of the six measured canals (Tasseron et al, 2023). For the Huveaune River in Marseille, Tramoy et al (2022) found that 36% of the annual macroplastic transport occurred during heavy rainfall events.…”

“…Another complicating factor is that plastic pollution comes in countless different polymer types, shapes, rigidity, and sizes, which all influence the way they move through in the environment (van Emmerik & Schwarz, 2020). It is clear that plastic is a purely anthropogenic pollutant, and increased concentrations are generally observed close to densely populated areas (Kuizenga et al, 2023; Tasseron et al, 2023). However, large accumulations are found around the world in parallel.…”