Hydrology as driver of floating river plastic transport

Emmerik, Tim van; Lange, Sjoukje Irene de; Frings, Roy; Schreyers, Louise; Aalderink, Heleen; Leusink, J.; Begemann, Finn; Hamers, Eric; Hauk, Rahel; Janssens, Niels; Jansson, Peter; Joosse, Nonna; Kelder, D.; Kuijl, T. van der; Lotcheris, Romi; Löhr, A.; Mellink, Yvette; Pinto, Rose Boahemaa; Tasseron, Paolo; Vriend, P.; Vos, Vivien

doi:10.1002/essoar.10510983.1

Cited by 8 publications

(19 citation statements)

References 38 publications

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“…Also within rivers the correlations are not trivial. For example, for the Dutch Rhine both positive and negative correlations were found between discharge and plastic transport (van Emmerik et al, 2022a). Our work feeds the hypothesis At both locations the gradient in an assumed linear relation between discharge and transport changes considerably between normal and flood conditions (see Figure 2).…”

Section: Discharge As Driving Factor Of Floating Plasticsupporting

confidence: 84%

“…The observed discharge and water level of the Meuse at Maastricht were extremely rare, and had a return period of 200 years (Strijker et al, 2021). As part of a one-year monitoring campaign (van Emmerik et al, 2022a), we quantified floating plastic transport during the flood wave at three locations along the Dutch Meuse. Directly after the flood we sampled plastics on 25 riverbanks, from the Dutch-Belgian border to the downstream confluence of the Meuse and Rhine.…”

Section: Introductionmentioning

confidence: 99%

“…Transport and retention of plastics within river systems are mainly driven by hydrological factors and river characteristics. The seasonal variation of floating plastic transport is in many cases related to river discharge, where increased discharge generally leads to considerably larger transport rates (van Emmerik et al, 2022a;Haberstroh et al, 2021). In particular, river discharge peaks have been hypothesized to play an important role in the transport and retention dynamics of plastics in rivers (Hurley et al, 2018;Roebroek et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Data was collected monthly, with additional observations during the July flood peak, as part of the first one-year monitoring effort in the Dutch rivers(van Emmerik et al, 2022a). At Maastricht, monthly data was collected from March to December, 2021, and during the flood peak on 15, 17 and 20 July, 2021.…”

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confidence: 99%

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River plastic during floods: Amplified mobilization, limited river-scale dispersion

Emmerik

Frings

Schreyers

et al. 2022

Preprint

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Plastic pollution in the world's rivers and ocean is increasingly threatening ecosystem health and human livelihood. In contrast to what is commonly assumed, most mismanaged plastic waste that enters the environment is not exported into the ocean. Rivers are therefore not only conduits, but also reservoirs of plastic pollution. Plastic mobilization, transport and retention dynamics are influenced by hydrological processes, and river catchment features (e.g. land-use, vegetation, and river morphology). Increased river discharge has been associated with elevated plastic transport rates, although the exact relation between the two can vary over time and space. The precise role of an extreme discharge event on plastic transport is however still unknown. Here, we show that fluvial floods drive plastic transport and accumulation in river systems. We collected unique observational evidence during the July 2021 flood along the complete Dutch part of the Meuse. Plastic transport multiplied with a factor of 141 upstream of the Dutch Meuse, compared to non-flood conditions, making the Meuse one of the most polluted rivers measured to date. Over one-third of the annual plastic transport was estimated to occur within the six-day period of extreme discharge. Towards the river mouth, plastic transport during the flood period decreased by 90\%, suggesting that the dispersal of plastic mobilized during the flood is limited due to the entrapment on riverbanks, in vegetation, and on the floodplains. Plastic accumulation on the riverbanks decreased significantly along the river, corroborating the river's function as plastic reservoir. Using new observational evidence, we demonstrate the crucial role of floods as driver of plastic transport and accumulation in river systems. Floods amplify the mobilization of plastics, but the effects are local, and the river-scale dispersion is limited. We anticipate that our findings serve as a starting point for improving global estimates of river plastic transport, retention, and export into the sea. Moreover, our results provide essential insights for future large-scale and long-term quantitative assessments of river plastic pollution. Reliable observations and a fundamental understanding of plastic transport are key to designing effective prevention and reduction strategies.

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Section: Discharge As Driving Factor Of Floating Plasticsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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River plastic during floods: Amplified mobilization, limited river-scale dispersion

Emmerik

Frings

Schreyers

et al. 2022

Preprint

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“…The combination of the river width and cross-sectional flow variations influence the optimal number of observation points across the river. Within the tidal zone of river systems, the bidirectional flow influences the required measurement frequency (accounting for daily and monthly tidal cycles) or timing (measuring during equal tidal phase) (van Emmerik et al, 2022a).…”

Section: River Characteristicsmentioning

confidence: 99%

Estimating plastic pollution levels in rivers through harmonized monitoring strategies

Emmerik

Kirschke

Schreyers

et al. 2023

Preprint

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Plastic pollution in freshwater environments is an emerging threat to ecosystem health and human livelihood. Plastics that accumulate in rivers and lakes over long time periods have direct local impact, and may eventually also reach the world’s oceans. Monitoring river plastic pollution is therefore key to quantify, understand and reduce plastics in all aquatic ecosystems. Unfortunately, global river plastic monitoring is still in its early stage. The lack of harmonization between ongoing monitoring efforts compromises the direct comparison and combination of available data. Recently, the United Nations Environment Programme (UNEP) launched guidelines on plastic monitoring in rivers and lakes, to provide a starting point for practitioners and scientists towards harmonized data collection, analysis, and reporting. Here, we demonstrate the application of those guidelines through a practical workflow to support to design effective plastic monitoring strategies. The workflow is a five-step iterative approach that aims to match the defined research goal or question to the available resources and river basin characteristics. To test the relevance of the workflow in different settings, we applied the workflow to three rivers across relevant gradients, including geography, hydrology, and plastic pollution levels. In the Rhine basin (Switzerland, France, Germany, the Netherlands) we showed that urban areas and tributaries may act as entry points of plastic pollution. For the Odaw basin (Ghana) we compared floating, terrestrial and riverbank plastics, identifying source and accumulation zones. Finally, in the Mekong river (Cambodia) we quantified the contribution of the city of Phnom Penh to plastic pollution through quantifying the plastic mass balance in the Mekong-Tonle Sap-Bassac region. We show that despite the simplicity of the selected methods and the limited duration of the data collection, a harmonized approach can provide crucial insights in the state of plastic pollution in very different river basins. Although each case study focused on one specific goal, each one is directly transferable to any river globally. Data collection is key in reaching local, regional and global goals on reducing plastic pollution. With our paper we aim to provide a simple workflow to support the design of effective and comparable river plastic monitoring strategies.

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Sample size requirements for riverbank macrolitter characterization

Lange

Mellink

Vriend

et al. 2022

Preprint

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Anthropogenic litter is omnipresent in terrestrial and freshwater systems, and can have major economic and ecological impacts. Monitoring and modelling of anthropogenic litter comes with large uncertainties due to the wide variety of litter characteristics, including size, mass, and item type. It is unclear as to what the effect of sample set size is on the reliability and representativeness of litter item statistics. Reliable item statistics are needed to (1) improve monitoring strategies, (2) parameterize litter in transport models, and (3) convert litter counts to mass for stock and flux calculations. In this paper we quantify sample set size requirement for riverbank litter characterization, using a database of more than 14,000 macrolitter items (>0.5 cm), sampled for one year at eight riverbank locations along the Dutch Rhine, IJssel and Meuse rivers. We use this database to perform a Monte Carlo based bootstrap analysis on the item statistics, to determine the relation between sample size and variability in the mean and median values. Based on this, we present sample set size requirements, corresponding to selected uncertainty and confidence levels. Optima between sampling effort and information gain is suggested (depending on the acceptable uncertainty level), which is a function of litter type heterogeneity. We found that the heterogeneity of the characteristics of litter items varies between different litter categories, and demonstrate that the minimum required sample set size depends on the heterogeneity of the litter category. More items of heterogeneous litter categories need to be sampled than of heterogeneous item categories to reach the same uncertainty level in item statistics. For example, to describe the mean mass the heterogeneous category soft fragments (>2.5cm) with 90% confidence, 990 items were needed, while only 39 items were needed for the uniform category metal bottle caps. Finally, we use the heterogeneity within litter categories to assess the sample size requirements for each river system. All data collected for this study are freely available, and may form the basis of an open access global database which can be used by scientists, practitioners, and policymakers to improve future monitoring strategies and modelling efforts.

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Hydrology as driver of floating river plastic transport

Cited by 8 publications

References 38 publications

River plastic during floods: Amplified mobilization, limited river-scale dispersion

River plastic during floods: Amplified mobilization, limited river-scale dispersion

Estimating plastic pollution levels in rivers through harmonized monitoring strategies

Sample size requirements for riverbank macrolitter characterization

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