The unknown fate of macroplastic in mountain rivers

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1016/j.scitotenv.2022.161224. This is version 3 of this Preprint.

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Authors

Maciej Liro, Tim van Emmerik , Anna Zielonka, Florin Constantin Mihai, Luca Gallitelli

Abstract

Mountain rivers are typically seen as relatively pristine ecosystems, supporting numerous goods (e.g., water resources) for human populations living not only in the mountain regions but also downstream from them. Recent evidence suggests, however, that mountain river valleys in populated areas can be substantially polluted by macroplastic (plastic item > 5 mm). It is, however, unknown how distinct characteristics of mountain rivers modulate macroplastic routes through them, which makes planning effective mitigation strategies difficult. To stimulate future works on this gap, here, we present a conceptual model of macroplastic transport pathways through mountain river. Based on this model, we formulate four hypotheses on macroplastic input, transport and degradation in mountain rivers. Then, we propose designs of field experiments that allow each hypothesis to be tested. We hypothesize that some natural characteristics of mountain river catchments (e.g., steep valley slopes, mass movements occurence) can accelerate the input of improperly disposed macroplastic waste from the slope to the river. Further, we hypothesize that specific hydromorphological characteristics of mountain rivers (e.g., high flow velocity) accelerate the downstream transport rate of macroplastic and, together with the presence of shallow water and coarse bed sediments, can accelerate mechanical degradation of macroplastic in river channels, accelerating secondary microplastic production. The above suggests that mountain rivers in populated areas can act as microplastic factories, which are able to produce more microplastic from the same amount of macroplastic waste inputted into them (in comparison to lowland rivers that have a different hydromorphology). The produced risks can not only affect mountain rivers but can also be transported downstream. The challenge for the future is how to manage the hypothesized risks, especially in mountain areas particularly exposed to plastic pollution due to waste management deficiencies, high tourism pressure, poor ecological awareness of the population and lack of uniform regional and global regulations for the problem.

DOI

https://doi.org/10.31223/X5F65D

Subjects

Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Monitoring, Geology, Geomorphology, Hydrology, Life Sciences, Natural Resources and Conservation, Sedimentology, Stratigraphy, Sustainability, Terrestrial and Aquatic Ecology, Water Resource Management

Keywords

plastic fragmentation, macroplastic storage, plastic degradation, secondary microplastic

Dates

Published: 2022-11-09 14:29

Last Updated: 2022-11-15 16:12

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License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data Availability (Reason not available):
this is perspective work without any specific dataset

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