Water dripping from a facade.© NAVEBGO

The transboundary aquifer of the Upper Rhine provides valuable ecosystem services for both drinking water supply and irrigation. These services must be protected now and for future generations. A recent study in a city district of Freiburg, Germany, demonstrated that biocides contained in paints and coatings of building facades end up in groundwater. This contamination by diuron, terbutryn, octhilinone and their transformation products is caused by the infiltration of polluted runoff water through urban drainage systems.

Similar contamination is likely in other urban areas of the Upper Rhine region. So far, however, a comprehensive inventory or risk assessment is lacking and most significant contamination pathways are unknown. Moreover, it is unclear if suitable alternatives are really applied by the actors involved (do-it-yourselfers, painting companies as well as policy makers).

There is an urgent need for action since these micropollutants accumulate and remain in groundwater for decades.

Overall, NAVEBGO aims at a strategy to sustainably reduce groundwater contamination by biocides in urban areas. The project has the following objectives:

1) By monitoring and hydrological modelling, NAVEBGO will document the transfer of biocides and their transformation products into groundwater. Studies will be carried out in urban areas of Landau, Freiburg and Strasbourg.

2) With the help of laboratory and field experiments, NAVEBGO will explore processes that govern the entry of biocides into groundwater.

3) By sociological analyses, NAVEBGO will identify chains of relevant actors as well as their perceptions and practices.

4) Finally, NAVEBGO will propose technical measures to reduce biocide infiltration, as well as alternatives to biocide use for facade protection of facades, and disseminate them to relevant stakeholders.

This strategy will be developed for three cities of different size (Strasbourg, Freiburg and Landau), but will be generally available and applicable to all urban areas in the Upper Rhine Valley.

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