Catalan Water Research Institute research and innovation for the sustainable use of water

A study analyzes the relationship between the presence of emerging pollutants and the biological quality of Catalan rivers

Friday, 25 September 2020

An investigation, carried out by theCatalan Water Research Institute (ICRA) and for theInstitute of Environmental Diagnosis and Water Studies – CSIC (IDAEA-CSIC), with the collaboration of theCatalan Water Agency (ACA), has analyzed the presence of pollutants in several rivers in Catalonia and their effects on biological quality (invertebrates and algae). The presence of new pollutants (emerging pollutants), even at very low levels, can lead to possible environmental problems, which is why the European Commission requires monitoring. It should be borne in mind that to evaluate the state of rivers, three indicators are taken into account: the physicochemical quality (water quality according to parameters of nitrates, phosphates, TOC), the hydromorphological quality (river continuity, morphology) and the biological quality (macroinvertebrates, diatoms and fish). The latter can be conditioned by the presence of various pollutants in the environment.

In this study, samples were taken at 89 control points from 16 Catalan rivers such as the Ebro and its tributaries; the Llobregat; the Ter; the Fluvian; the Muga; the Foix, the Francolí; the Besòs, the Tordera river, among others, with the aim of verifying the presence of these emerging pollutants and their possible effects on biological communities in compliance with the Water Framework Directive (DMA).

The presence of some medicines – mainly antibiotics and anti-inflammatories -, heavy metals such as nickel, and pesticides such as diuron has been detected in a high number of samples (in 80% of the samples taken). The highest concentrations of pollutants are found in the rivers with the lowest dilution capacity, in which a large part of their flow is nourished almost exclusively by the contributions of urban and/or industrial waste water. These are often river sections with a high population density (the Llobregat and Foix rivers, in their middle and lower sections, to give two examples) and, to a lesser extent, in the upper reaches of rivers such as the Segre and the two Nogueres. This, according to research, may be the cause of a loss of biological quality associated with macroinvertebrates (insects, crustaceans, molluscs, among others) in these stretches of rivers, as well as diatoms (main group of ‘fluvial algae).

No risk for drinking water

The presence of these pollutants does not pose a risk to people’s health, since the levels are within what is established by the regulations, and the water for human consumption goes through a potabilization treatment that guarantees its healthiness . This research expresses the need to develop specific studies on the ecological impact of these pollutants and promote their inclusion in European basin management plans.