Microplastic contamination of river beds significantly reduced by catchment-wide flooding

Hurley, Rachel; Woodward, Jamie; Rothwell, James

doi:10.1038/s41561-018-0080-1

Cited by 736 publications

(462 citation statements)

References 108 publications

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“…A study on lakes in the Bistrita river catchment in Romania demonstrated that plastic transport from rural areas into rivers and lakes was also mainly driven by floods. The importance of floods for plastic transport is supported by Hurley et al (2018) who found a 70% decrease in microplastics in river sediments across the United Kingdom after heavy floods. With the available global flood risk models (Ward et al, 2015), assessments should be made on where to expect additional plastic debris transport as a result of riverine, marine, or compound flood events.…”

Section: Extreme Eventsmentioning

confidence: 94%

Plastic debris in rivers

2019

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Plastic pollution in aquatic ecosystems is an emerging environmental risk, as it may negatively impacts ecology, endangers aquatic species, and causes economic damage. Rivers are known to play a crucial role in transporting land‐based plastic waste to the world's oceans, but riverine ecosystems are also directly affected by plastic pollution. To better quantify global plastic pollution transport and to effectively reduce sources and risks, a thorough understanding of origin, transport, fate, and effects of riverine plastic debris is crucial. In this overview paper, we discuss the current scientific state on plastic debris in rivers and evaluate existing knowledge gaps. We present a brief background of plastics, polymer types typically found in rivers, and the risk posed to aquatic ecosystems. Additionally, we elaborate on the origin and fate of riverine plastics, including processes and factors influencing plastic debris transport and its spatiotemporal variation. We present an overview of monitoring and modeling efforts to characterize riverine plastic transport, and give examples of typical values from around the world. Finally, we present an outlook to riverine plastic research. With this paper, we aim to present an inclusive and comprehensive overview of riverine plastic debris research to date and suggest multiple ways forward for future research. This article is categorized under: Science of Water > Water Quality Water and Life > Stresses and Pressures on Ecosystems

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Section: Extreme Eventsmentioning

confidence: 94%

Plastic debris in rivers

2019

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“…Assessing the fate of a cloud of sediments in rivers is crucial for determining, for example, the extent of a solid-phase contamination (Lajeunesse et al, 2013), the accumulation of cosmogenic radionuclides in sediment transport (Bradley et al, 2010), and, what is the subject of particular concern to date, the storage and transfer of microplastics in surface waters. In their study, Hurley et al (2018) have shown that microplastic contamination in rivers is comparable to and, possibly, the source of ocean plastic content. Plastic fragments (attaining the size of 4-5 mm) move as discrete particles or they can be stored into the channel bed, where they pose a risk to the riverine ecosystem and from where they can be remobilized and transported downstream to estuarine areas.…”

Section: Introductionmentioning

confidence: 94%

Diffusive Regimes of the Motion of Bed Load Particles in Open Channel Flows at Low Transport Stages

Cecchetto

Tregnaghi

Bottacin‐Busolin

et al. 2018

Water Resources Research

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The stochasticity of fluid and sediment parameters has been identified as a source of diffusion, particularly anomalous diffusion at different temporal and spatial scales of bed load particle trajectories. Data from two sets of flume experiments are presented, one data set has gravel particle trajectories tracked over a limited area and was used in identifying the influence of different shear stress conditions on diffusive processes. A new experiment was performed using spherical particles moving as bed load in an annular flume in order to address concerns about censorship effects caused by the size of the detection window. An annular flume allowed collection of practically uncensored particle trajectories over longer time period than has been previously possible in the laboratory. Three diffusive regimes were observed at distinct stages of particle motion: (i) ballistic regime at the local range; (ii) Fickian diffusion at the intermediate range; (iii) subdiffusion at the global range. Characteristic time scales separate the regimes and correlate with the mean traveling and resting times of particles. Fickian diffusion in the intermediate range is first recognized as a result of the balance between intermittent weak transport and near‐bed turbulence, as first predicted by Nikora et al. (2002, https://doi.org/10.1029/2001WR000513). In the global range, extreme values were observed in the distribution of particle resting times, suggesting that two types of distributions (related to surface motion and vertical mixing) were responsible for the subdiffusion at longer time scales. Diffusion was found to be anisotropic at all stages of particle motion.

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“…The interaction between storage and flux processes is highlighted in a recent study by Hurley et al (), which indicates the significant mobilization and removal of sedimentary microplastics in response to high flow events. In this example, 0.85 ± 0.27 tonnes of plastic was removed from a single catchment during an individual flood event (Hurley et al, ). Similar flood events may also be responsible for distributing plastics onto floodplains.…”

Section: Fluxes Of Plastics Through Hydrological Catchmentsmentioning

confidence: 94%

“…Understanding where and how high plastic concentrations arise in space and time is required for assessments detailing how plastic concentrations may vary across hydrological catchments. The importance of such developments is further emphasized by a recent study which identified the highest concentration of microplastics yet recorded within riverine sediments globally (517,000 MP/m 2 ) (Hurley et al, ). Assessments of heterogeneity are required at a range of spatial scales, from local patch dynamics at centimetre to metre scales, to comparisons between entire habitats and ecosystems.…”

Section: Future Research At the Catchment‐scalementioning

confidence: 99%

“…As a result of the ubiquity of point and diffuse sources of plastic pollution within freshwaters, it is not surprising that plastic has been widely identified within a range of freshwater habitats (Free et al, 2014;Horton, Walton et al, 2017). Data from freshwater systems, thus far, indicate that these systems are important hotspots of plastic pollution, holding some of the highest concentrations of (micro)plastics recorded in either water and sediments across the globe (Hurley, Woodward, & Rothwell, 2018;Mani, Hauk, Walter, & Burkhardt-Holm, 2015).…”

Section: Freshwater Systemsmentioning

confidence: 99%

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A catchment‐scale perspective of plastic pollution

Windsor

Durance

Horton

et al. 2019

Global Change Biology

309

147

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Plastic pollution is distributed across the globe, but compared with marine environments, there is only rudimentary understanding of the distribution and effects of plastics in other ecosystems. Here, we review the transport and effects of plastics across terrestrial, freshwater and marine environments. We focus on hydrological catchments as well‐defined landscape units that provide an integrating scale at which plastic pollution can be investigated and managed. Diverse processes are responsible for the observed ubiquity of plastic pollution, but sources, fluxes and sinks in river catchments are poorly quantified. Early indications are that rivers are hotspots of plastic pollution, supporting some of the highest recorded concentrations. River systems are also likely pivotal conduits for plastic transport among the terrestrial, floodplain, riparian, benthic and transitional ecosystems with which they connect. Although ecological effects of micro‐ and nanoplastics might arise through a variety of physical and chemical mechanisms, consensus and understanding of their nature, severity and scale are restricted. Furthermore, while individual‐level effects are often graphically represented in public media, knowledge of the extent and severity of the impacts of plastic at population, community and ecosystem levels is limited. Given the potential social, ecological and economic consequences, we call for more comprehensive investigations of plastic pollution in ecosystems to guide effective management action and risk assessment. This is reliant on (a) expanding research to quantify sources, sinks, fluxes and fates of plastics in catchments and transitional waters both independently as a major transport routes to marine ecosystems, (b) improving environmentally relevant dose–response relationships for different organisms and effect pathways, (c) scaling up from studies on individual organisms to populations and ecosystems, where individual effects are shown to cause harm and; (d) improving biomonitoring through developing ecologically relevant metrics based on contemporary plastic research.

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Microplastic contamination of river beds significantly reduced by catchment-wide flooding

Cited by 736 publications

References 108 publications

Plastic debris in rivers

Plastic debris in rivers

Diffusive Regimes of the Motion of Bed Load Particles in Open Channel Flows at Low Transport Stages

A catchment‐scale perspective of plastic pollution

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