MICROPOLLUTANTS ISSUES: A MODELLING STUDY OF HEAVY METALS WITHIN TWO FRENCH BASINS AND A TEST APPLICATION TO COCAINE IN BELGIUM

European policies (European Framework Directive: Water 2000/60/CE, Directive 76/464/CE) impose to reduce the releases of about a hundred substances in surface water. In the last years, the AQUAPOLE has been involved in two studies related to this matter.

First, on the request and with the financial support of both the French Ministry of Environment and ONEMA (“Office National de l’Eau et des Milieux Aquatiques”), INERIS (“Institut National de l’Environnement Industriel et des Risques”) drew up the guidelines of a methodology allowing fixing the local Limit Values to Emission so as to abide by the quality standards on the whole watershed. Within this context, INERIS wishes to test the use of pollutant transfer models on pilot sub-basins. The PEGASE model has been used to simulate micropollutants on two concrete use cases (1):
(iii) in the Meuse sub-basin, managed by the French Water Agency Rhine-Meuse, for simulations concerning cadmium and zinc;
(iv) in the Adour sub-basin, managed by the French Water Agency Adour-Garonne, for simulations applied to cadmium and copper.
The choice of each substances and sub-basins was made by mutual agreement between INERIS, the concerned Water Agencies, and the AQUAPOLE. A major selection criterion for the substances and the sub-basins was the availability of data (sources and in situ measurements).

For the second study, the PEGASE model has been adapted to describe the cocaine’s behaviour (using a stable metabolite of the cocaine in the environment: the benzoylecgonine (BZE)) in waste water, waste water treatment plants (WWTP) and surface water (2). The cocaine is newly described in the model as an additional micropollutant (PEGASE already treats numerous heavy metals), thanks to the implementation of new state variable equations and their specific parameterizations. Simulations of BZE have been done in the Walloon and Flemish regions, where many measurements from the COWAT project (3) were available.

The first results are showing good agreement between calculated and measured values. The ability of the model to simulate the fate of studied micropollutants (cadmium, zinc, copper, and the cocaine derivatives) in surface waters should be enhanced and extended to other substances and basins. Moreover, additional data still have to be collected and measured.