A river runs through it

Louis Dorémus, Marina Antonova, Joan Fabres

By GRID-Arendal

April 26^th, 2018

A story by the British Broadcasting Corporation caught our eye last week when it reported that the Indonesian government had called in the army to help clear rivers choked with plastic garbage near the city of Bandung.

Bandung is Indonesia's third largest city and home to more than 8 million people. The BBC reported “the shocking sight of a concentration of plastic waste so thick that it looked like an iceberg and blocked a major tributary.”

Soldiers on a barge used nets to try to collect “bags, Styrofoam food boxes and bottles, a seemingly futile task because all the time more plastic flowed their way from further upstream.”

Indonesian soldiers taking a break during river clean up (photo Kate Stephens BBC News)

The story underlines the global problem of plastic pollution. Because it is light and durable, plastic can be easily transported by rivers and the wind. Much of this debris ends up in the ocean. Indonesia isn’t the only example, of course. A GRID-Arendal project on Wastewater Management and Sanitation Provision in Africa has documented a similar problem in Kibera, a large informal community on the edge of Nairobi.

A garbage-choked river in Kibera, Kenya (photo Rob Barnes/GRID-Arendal)

Recent research indicates that a large share of plastic in the ocean is likely to originate from land – as much as 13 million tonnes could be flowing in every year. Cutting the amount of plastic entering rivers and preventing it from getting into the ocean is therefore crucial to reducing global marine pollution. To date there has been little research on rivers and freshwater systems to measure worldwide flows of plastic.

However, one recent study tries to overcome this problem by using proxy data to estimate plastic coming from rivers at a global level. This data includes population density, indicators of waste (mis)management and catchment runoff.

The study estimated that between a quarter and a fifth (between 1.15 and 2.41 million tonnes) of the plastic entering the oceans every year does so through rivers and streams. According to that same study, the top 20 polluting rivers are mostly located in Asia and account for more than two-thirds of the global annual input from rivers. Factors such as rapid growth, high population density and poor waste management drastically increase the concentration of plastic litter in rivers.

Nevertheless, rivers also offer an opportunity to control the waste getting into the oceans. That’s because pollution sources are easier to trace back along the stream, rather than in the open seas where marine debris is “orphaned” and difficult to trace. While still challenging, it is also easier to remove plastic debris from rivers than from oceans.

Beyond the contribution of rivers to ocean pollution, the contamination of freshwater systems by plastic and the toxic substances associated with it is a concern because of implications for habitats, aquatic life, water quality and the food chain. Researchers estimate that plastic contamination in freshwater ecosystems may be almost equal to that of oceans. That said, there are still relatively few studies done on the source, distribution, flow and effects of plastic in rivers and lakes.

Human activity and population density directly affect plastic pollution in the environment, yet withoutproperwaste management services high levels of waste-related pollution can be found even in remote and sparsely populated areas. A study that looked at remote lakes on the Tibetan plateau found levels of microplastics comparable to those in the more populated and industrialized North American Great Lakes. As the study suggests, such high levels in the Tibetan Plateau could be due to the lack of adequate waste disposal and recycling systems.

To take action, we need more knowledge, obtained through better coordinated studies. Several studies highlight the urgent need to improve our understanding on the transport, distribution and impacts of plastics in freshwater systems, and the need to harmonise and develop our methods to monitor it.

Combatting plastic pollution in rivers will help keep waste out of the oceans and for that to happen, action needs to happen directly at the source. Better waste management will limit plastic litter. Raising awareness to motivate change in production and consumption practices is also needed.