EGU2020-3968
https://doi.org/10.5194/egusphere-egu2020-3968
EGU General Assembly 2020
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

River corridors as global hotspots of microplastic pollution

Stefan Krause, Jennifer Drummond, Holly Nel, Jesus Gomez-Velez, Iseult Lynch, and Greg Sambrook Smith
Stefan Krause et al.
  • University of Birmingham, School of Geography, Earth and Environmental Sciences, School of Geography, Earth and Environmental Sciences, Birmingham, United Kingdom of Great Britain and Northern Ireland (s.krause@bham.ac.uk)

The total production of plastics is estimated to be~ 10 billion metric tons, half of which is thought to have ended up as waste in the environment. However, the total mass of plastic found in the world’s ocean garbage patches has been calculated as less than 1 million metric tons, a paradox that leaves the whereabouts of the majority (>99.9%) of plastic waste produced so far unexplained.

 

Recent research suggests that the accumulation of plastic (in particular microplastic < 5mm in size) in river corridors may be even greater than that  in the world’s oceans. Our model-based quantifications reveal that rivers do not solely function as pure conduits for plastics travelling to the oceans, but also represent long-term sinks, with in particular microplastics being buried in streambeds and floodplain sediments. This includes the development of pronounced hotspots of long-term plastic accumulation, evidencing that these emerging pollutants have already developed a pollution legacy that will affect generations to come.

 

The principles that govern the spatially and temporally dynamic inputs of plastics into river corridors as well as the fate and transport mechanisms that explain how plastics are transported and where they accumulate are still poorly understood. Experimental evidence of microplastic pollution in river corridors is hampered by the absence of unified sampling, extraction and analysis approaches, inhibiting a comprehensive investigation of global source distributions and fate pathways. We have therefore initiated the 100 Plastic Rivers programme to provide a global baseline of microplastic pollution in rivers, their drivers and controls in order to develop mechanistic understanding of their fate and transport dynamics and create predictive capacity by informing the parameterisation of global plastic transport models. Preliminary results evidence the suitability of the 100 Plastic Rivers approach and help validate our predictions of global plastic storage in river corridors.

How to cite: Krause, S., Drummond, J., Nel, H., Gomez-Velez, J., Lynch, I., and Sambrook Smith, G.: River corridors as global hotspots of microplastic pollution, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3968, https://doi.org/10.5194/egusphere-egu2020-3968, 2020

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Display material version 1 – uploaded on 04 May 2020
  • CC1: Comment on EGU2020-3968, Winnie Courtene-Jones, 05 May 2020

    Hello, interesting and a great deal of work - i look forward to reading the 100 Rivers paper once out. my question is about the classification of plastics along River Tame, and the distinction between fragments and commercial fragments - how do you tell these apart? 
    Also, why do you think there is such a high abundance at T3? One would think that Ford Brook (is that FBm on the plot?) would have high abundance being located after the wwtw. 
    Thank you 

    • AC1: Reply to CC1, Stefan Krause, 05 May 2020

      Hi Winnie - that's a really interesting one ideed. We found that WWTPs were not significantly increasing river concentrations in this river (and at this time) but sources (and their relative contributions) do of course vary a lot between different systems. Our main finding was that while we saw downstream increase in concentrations (as one would expect), that reductions in flow velocities (standing waters) reduced river concentrations due to sedimentation etc. This means, concentrations were neither related much to upstream catchment population nor to main WWTP discharge points. What will be really important in future is identifying what fraction of particles is retained in what times of reservoirs and storage zones - current models of plastic contributions to the oceans assume that they originate only from areas downstream of mayor dams, which does not exactly match what is known from classic sedimentology research, but there is little field evidence so far.

      Re 'industrial fragments' this wasn't the most useful terminology and we don't use this anymore, but basically referred to particles of +/- regular shapes like nurdles - a rather uncertain distinction, in particular for environmentally aged particles.