Why quantifying plastic pollution beyond the world's oceans represents the next frontier
While over the last two decades the increasingly interested public as well as the scientific community have been primarily concerned about the vast amounts of plastics floating in the colossal garbage patches at the surface of the world’s oceans, these 36,000 - 230,000 metric tons represent less than 1 percent of the mismanaged plastic waste that enters the environment every year.
If we consider the almost 5 billion tons of mismanaged waste that have been discarded into the environment over the last century, the surge in public interest in the environmental fate and potential accumulation of plastics outside marine ecosystems may be less surprising. The recent success of the Ocean Clean-Up operation, that for the first time managed to efficiently capture plastics in the Great Pacific Garbage Patch, is promising news for reducing the amount and the impact of plastic waste already accumulated in the world’s oceans, yet it presents a Sisyphean task if we will not succeed to reduce the inflows of plastic waste from its terrestrial and aquatic sources. In addition, despite the justifiable concerns of the environmental impacts of plastic waste in the oceans and in coastal areas, there remain critical knowledge gaps in particular regarding the impacts of plastics on aquatic and terrestrial ecosystem services and public health.
Assessing the impacts of terrestrial sources of plastic waste on marine and freshwater ecosystem functioning and consequently also public health will require a detailed understanding not only of the spatial distributions of different sources of environmental plastics but also of their time-variant activation, as well as their fate and transport along different environmental flow pathways, including their long-term accumulation in river corridors, soils, or groundwater aquifers. The 100 Plastic Rivers Programme at the University of Birmingham therefore aims at producing the world’s first comprehensive baseline of plastic pollution in river corridors as main transport pathways and accumulation zones of terrestrial plastic waste. The programme deploys participatory sampling approaches in order to pioneer a global freshwater plastics database that will include quantitative information of plastic concentrations in freshwater and sediments as well as qualitative information of synthetic polymer types and plastic associated pollutants.
The recent increase of research into the fate, transport and impact of particularly microplastics (particles of less than 5mm size) in terrestrial and aquatic environments has been partially hampered by the lack of standardised sampling and analysis protocols, impeding global assessments and regional comparisons of experimental observations. This current lack of comparability in reported field studies prevents the identification of plastic risks to ecosystems and society as well as targeted clean-up or remediation strategies. We are therefore assembling an international team of interdisciplinary experts within a recently funded NERC Global Partnerships Seedcorn Fund grant in order to establish globally comparable standards for microplastic sampling and reporting as well as the development of new numerical modelling approaches for the quantification of overall freshwater plastic fluxes to the oceans.
Our work challenges existing paradigms in the global quantifications of plastic waste that are based on the assumption that plastic waste inputs into the world’s oceans would be limited to inputs from coastal populations, excluding the plastic waste transported and stored in many of the worlds heavily polluted large river networks. Our recent model predictions show that the exclusion of large river networks that are carriers of substantial amounts of plastic waste, connecting terrestrial sources and marine sinks would cause critically underestimations of the real global plastic fluxes and long-term pollution legacy. Together with UK and international partners we are therefore pioneering whole river network wide plastic sampling in large river networks. A first campaign at the River Ganga in India will commence in November 2019, with other large Asian rivers to be analysed for plastic pollution hotspots and hot moments in 2020, providing unique insights into what types of plastics are accumulating in river networks and how they are changing along their environmental passage. The scientifically and logistically challenging river network wide plastic surveys are supported by the University of Birmingham charitable funding campaign Birmingham In Action.
Professor Dr Stefan Krause, School of Geography, Earth and Environmental Sciences.
(With contributions from Iseult Lynch, Greg Sambrook Smith, Holly Nel and Jen Drummond.)