Freshwater signals

Page Last modified 08 Dec 2022
This section of the zero pollution monitoring assessment presents a series of short case studies that highlight additional sources of information on the impacts of pollution on freshwater ecosystems.

Freshwater Signal 1: Emerging substances

Many different emerging substances of concern, such as pesticides and biocides, personal care products, pharmaceuticals, food additives, textiles and plastics, reach Europe’s waters from a variety of sources. These chemical substances and their mixtures may adversely affect organisms, populations and communities. Monitoring, modelling and assessing the risks from chemicals in European water resources is challenging because of the large number of substances. Moreover, there is often no standardised method of analysing these substances.

The European project Solutions has developed models to provide further knowledge and fill the data gaps regarding emerging chemicals of concern. After modelling was carried out for individual substances, the toxic risks posed by 1,785 chemicals produced in Europe in aquatic ecosystems were simulated. In parallel, the ways in which certain chemical mixtures could become toxic — and why — were identified. Map 1 shows the potentially affected fraction of species in various river basins (Van Gils et al., 2019).

Map 1. SOLUTIONS project output simulating the impact of chemical mixtures on a potentially affected fraction of species (msPAF) and highlighting regions where there could be significant chemical pollution pressure on freshwater species

Source: Van Gils et al. (2019).

Click here for different chart formats and data

Solutions addresses significant gaps in assessing emerging pollutants and provides innovative approaches to evaluating their effects on water resources. The project’s overall goal is to produce consistent solutions for many legacy, present and future chemicals posing a risk to European water bodies.

More information is available on the Solutions project website.



Van Gils, J., et al., 2019, ‘The European collaborative project SOLUTIONS developed models to provide diagnostic and prognostic capacity and fill data gaps for chemicals of emerging concern’, Environmental Sciences Europe 31, 72 (

Freshwater Signal 2: Microplastics

Microplastics have been investigated for over 45 years, especially in the marine environment. In recent years, research has also focused on microplastics in freshwater environments. Microplastic pollution can reach surface water in several ways. First, microplastics that originate from personal care products or textile fibres discharged while laundering clothes can be released through wastewater treatment plants. They are also released when biosolids from wastewater treatment plants are applied to agricultural land. Moreover, storm water overflows, industrial products or processes, atmospheric fibre deposition and other types of incidental releases (e.g. from vehicle tyre wear) can also emit microplastics to surface waters (Lambert and Wagner, 2018).

Studies have investigated microplastics in the European rivers Rhine, Danube, Weser, Antuã, Meuse, Seine and Rhône, as well as in smaller rivers and tributaries in the United Kingdom. Reported microplastic concentrations varied significantly, ranging from 0.03 to 187,000 particles/m3. In sediments, concentrations ranged between 18 and 72,400 particles/kg. Moreover, in the large River Elbe, microplastic concentrations were on average 600,000-fold higher in sediments than in the water (Scherer et al., 2020). In one of the recent studies conducted in the Słupia and Łupawa rivers in Poland, microplastic particles were detected in 62.5% of river water samples (Piskuła and Astel, 2022).

The clear conclusion is that microplastics are now abundant in freshwater environments in Europe. However, information on their impact on biodiversity, movement through the food chain, and ability to change species diversity or alter predator-prey interactions is still limited. To date, studies have tended to focus on the toxic effects of microplastics in laboratory settings — meaning that many of these questions remain unanswered in the real-world context (Sarijan et al., 2021; Yardy et al., 2022). However, microplastics are an urgent pollution issue and additional research is immediately needed to better understand their impacts.



Lambert, S. and Wagner, M., 2018, ‘Microplastics are contaminants of emerging concern in freshwater environments: an overview’, in: Wagner, M. and Lambert, S. (eds), Freshwater microplastics: emerging environmental contaminants?, Springer Open,pp. 1-23 (978-3-319-61615-5.pdf (

Piskuła, P. and Astel, A. M., 2022, ‘Microplastics occurrence in two mountainous rivers in the lowland area — a case study of the central Pomeranian region, Poland’, Microplastics 1(1), pp. 167-185 (

Sarijan, S., et al., 2021, ‘Microplastics in freshwater ecosystems: a recent review of occurrence, analysis, potential impacts, and research needs’, Environmental Science and Pollution Research 28, pp. 1341-1356 (

Scherer, C., et al., 2020, ‘Comparative assessment of microplastics in water and sediment of a large European river’, Science of the Total Environment 738, 139866 (

Yardy, L. D., et al., 2022, ‘Microplastics in freshwater ecosystems with special reference to tropical systems: detection, impact, and management’, Emerging Freshwater Pollutants pp. 151-169 (

Cover image source: © Panagiotis Dalagiorgos, Well with Nature /EEA


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