River corridors are global hotspots of microplastic pollution, exceeding the amount of plastics found in the world's oceans
Abstract
The total production of plastics is estimated to be approximately 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 that have been the focus of the scientific community and in the public eye 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.
We show in this study that the accumulation of plastic (in particular microplastic < 5mm in size) in river corridors is several orders of magnitude greater than the amount of plastics found in the world's oceans. Our model-based quantification reveals 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.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H42D..06K
- Keywords:
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- 1803 Anthropogenic effects;
- HYDROLOGY;
- 1834 Human impacts;
- HYDROLOGY;
- 1871 Surface water quality;
- HYDROLOGY;
- 1879 Watershed;
- HYDROLOGY