The cross-border Upper Rhine aquifer provides valuable ecosystem services for both drinking water supply and irrigation, which must be protected now and for future generations. In a recent study carried out by the project executing agency in a district of Freiburg, a clear groundwater influx of biocides and their transformation products from film protection agents for architectural paints and plasters was demonstrated using Diuron, Terbutryn and Octhilinon as examples. This was achieved by infiltration of contaminated runoff into urban infiltration structures.

Similar entries are likely in other urban areas in the area of the Upper Rhine aquifer. However, no comprehensive inventory or risk assessment has yet been carried out for this inflow path. In particular, it is not known at which points the most significant groundwater entry occurs and whether there are sensible alternatives to the use of biocides on facades, which are actually used by the relevant actors (from do-it-yourselfers and painters to political decision-makers).

There is therefore an urgent need for knowledge and action, as micropollutants can remain in groundwater for decades and accumulate in various places.
NAVEBGO is developing a strategy to sustainably reduce the contamination of the Upper Rhine aquifer by biocides from settlement areas. The project pursues the following objectives:

Through site inspections, monitoring and hydrological modelling, NAVEBGO aims to document the existing input of biocides and their transformation products in the districts of Landau, Freiburg and Strasbourg.
NAVEBGO will use laboratory and field experiments to investigate the processes involved in groundwater discharge.
NAVEBGO wants to identify the affected chains of actors and their perceptions and practices through sociological actor analyses.
Finally, NAVEBGO would like to examine technical measures for the reduction of inputs and alternatives to the use of biocides in façade protection and disseminate them among the relevant actors.

The strategy will be developed for three cities of different sizes (Strasbourg, Freiburg, Landau), but is generally available and applicable to all settlement areas in the Upper Rhine.

Project coordinator at the University of Freiburg: Jens Lange, jens.lange hydrology.uni-freiburg de

Projektwebsite: www.navebgo.uni-freiburg.de/de