When we think of plastic pollution, the image of islands of waste floating in the middle of the Pacific often comes to mind. But the reality is closer, more insidious, and sometimes invisible. Before reaching the oceans, most plastics pass through rivers, lakes and canals. And it’s here, in these freshwater environments, that plastic pollution is beginning to wreak havoc… still largely underestimated.
Plastics: persistent, multiform, global pollution
Every year, over 9 million tonnes of plastic end up in aquatic environments, according to the United Nations Environment Programme. Packaging, tire fragments, synthetic textiles, microbeads… This waste comes from many sources: urban waste, agricultural runoff, poorly managed landfills, industrial effluents.
Once in the water,the plastic doesn’t disappear. It fragments into smaller and smaller particles – microplastics (less than 5 mm), even nanoplastics invisible to the naked eye – which persist for decades. Contrary to popular belief, this process is not limited to the oceans : freshwater environments are at once points of entry, storage and exposure.
Freshwater ecosystems under pressure
Rivers, ponds, wetlands… These often neglected environments are home to exceptional biodiversity. But they are also the most exposed to human pressures. Plastics accumulate in sediments, attach themselves to aquatic plants and are ingested by invertebrates, fish and birds…
The consequences are manifold:
- Obstruction of the animal’s digestive system, which can lead to eating disorders and even death.
- Toxic effects of chemical additives (phthalates, bisphenol A, flame retardants) incorporated into plastics.
- Bioaccumulation throughout the food chain, with as yet poorly understood risks to human health.
- Alteration of natural cycles, such as the decomposition of organic matter or the quality of oxygenation.
Current scientific work seeks to quantify these impacts, identify areas at risk, and understand how organisms react to these emerging pollutants.Current scientific work seeks to quantify these impacts, identify areas at risk, and understand how organisms react to these emerging pollutants.
Increasingly precise tools for tracking the invisible
Tracking plastic pollution in the aquatic environment is a scientific challenge. These pollutants are heterogeneous, mobile and often microscopic. But today’s researchers have access to increasingly sophisticated methods:
- Fine-mesh nets and filter pumps to collect microplastics on the surface or at depth.
- Infrared spectroscopy and chemical analysis to identify polymers.
- Imaging and AI to differentiate plastic particles from natural debris.
- eDNA (environmental DNA) to detect the impact of plastics on biodiversity.
This research enables us to map flows, identify the main sources of pollution, and test the effectiveness of solutions such as filters in wastewater treatment plants, floating booms and alternative materials.
Thinking of rivers as essential links in the transition
Long regarded as mere drainage channels, rivers are now recognized as key ecosystems in the fight against plastic pollution. Scientists advocate a systemic approach, which considers the watershed as a whole: upstream activities, land use, infrastructure, consumer behavior…
This vision also integrates the need for interdisciplinary cooperation: ecology, hydrology, materials chemistry, social sciences… because the causes of pollution are multiple, and so must be the responses.
Understanding for better prevention
If plastics are a global problem, their study in freshwater environments offers a closer, more concrete, more measurable scale. This is where sustainable solutions can emerge , adapted to local realities. And this is also where research plays a decisive role, by documenting effects, warning of invisible risks, and supporting the transformation of practices.
Understanding plastic pollution means more than simply denouncing a catastrophe: it means revealing complex mechanisms, tracing trajectories, and equipping societies to finally reverse the trend.