The Challenge of Detecting Microplastics in Swiss Rivers and Lakes

Microplastics are tiny pieces of plastic that range from micro to millimeter in size. They can come from various sources, such as cosmetics, clothing, or the degradation of larger plastic items.

Microplastics can pose a threat to the environment and human health, as they can accumulate in soils, waterways, and organisms.

In this article, we will look at how researchers have quantified the amount and distribution of microplastics in Swiss rivers and lakes, and what implications this has for the future.

A model to predict the microplastic concentration

(Photo : Sean Gallup/Getty Images)

Measuring the concentration of microplastics in water is not a simple task, as it requires sampling, filtering, and analyzing the water samples. Moreover, the concentration can vary depending on the time, location, and method of measurement, as per Phys.org.

Therefore, researchers from the Swiss Federal Laboratories for Materials Science and Technology (Empa) have developed a model that can predict the concentration of microplastics in Swiss waterbodies based on their sources and transport.

The model uses data from a previous study that estimated the annual release of seven common plastic polymers into the Swiss environment: polyethylene (LD-PE and HD-PE), polypropylene, polystyrene and expanded polystyrene, PVC, and PET.

These polymers are used for packaging, textiles, insulation, and agricultural films. The model also considers the degradation and abrasion of macroplastics into microplastics, as well as the removal of microplastics by wastewater treatment plants.

The model can calculate the concentration of microplastics in any river or lake in Switzerland, as well as their transport to neighboring countries.

The researchers validated the model by comparing its predictions with measurements from several water samples collected across Switzerland.

Also Read: Microplastics Found in 75% of Fish Meant for Human Consumption: Is It Still Healthy to Eat Seafood?

The results: where do microplastics end up?

According to the model, about 14,000 tons of plastic end up in Swiss soils and waters every year. Of this amount, about 15 tons are microplastics that enter Swiss rivers and lakes. However, not all microplastics stay in Switzerland, as per WN.

About half of them are transported to other countries by rivers, mainly by the Rhine. The Rhine near Basel contains the highest concentration of microplastics in Switzerland, as it receives inputs from several large cities such as Bern, Zurich, and Lucerne.

About a third of the microplastics that enter Swiss waters settle in lakes, where they can accumulate over time.

The concentration of microplastics in lakes depends on their size, depth, and water exchange rate. For example, Lake Geneva has a lower concentration than Lake Zurich, because it is larger and has a faster water turnover.

The distribution of microplastics in rivers is more complex, as it is influenced by the river basin, the barrages, and the lakes along the way.

A longer river does not necessarily retain more microplastics than a shorter one. For instance, the Rhone retains less microplastics than the Aare, even though it is longer.

The implications: what can we do about microplastics?

The model developed by Empa researchers provides a useful tool to assess the extent and sources of microplastic pollution in Swiss waterbodies.

It can also help to identify hotspots and potential mitigation measures. For example, reducing the use of plastic packaging or improving the efficiency of wastewater treatment plants could reduce the number of microplastics entering the environment.

However, the model also has some limitations and uncertainties. For instance, it does not account for the effects of weathering, biofouling, or ingestion by organisms on microplastics.

It also does not consider other types of plastic polymers or additives that may have different properties or impacts.

Therefore, more research is needed to understand the fate and effects of microplastics in aquatic ecosystems.

Moreover, more actions are needed to prevent and reduce plastic waste at its source. As Nowack, one of the authors of the study, says: "We need to rethink our use of plastics".