Abstract
(Englisch)
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Pesticide concentrations greater than the accepted potability standards (0.1 µg L-1) have been reported in many European ground water (GW) used for drinking water supplies. The question of how this will evolve cannot at present be answered. This is why the hydro-geologists, soil scientists and socio-economists of PEGASE address the key processes involved in the pesticide contamination of six contrasted aquifers representative of European GW resources. A 32-months detailed field monitoring, supported by laboratory work, will be the basis for the development, calibration and performance assessment of predictive modelling tools. At the same time, alternative scenarios of agricultural practices will be established and tested with the developed tools so as to provide a socio-economic assessment of the implementations of alternative land uses and agricultural practices on GW quality.
Scientific objectives and approach:
The global objective of PEGASE is to enable predictive modelling of pesticide contamination of representative European aquifers, and assessment of socio-economic implications of the present and future contamination. Specific objectives and innovations are the:
- Production of high quality data sets with intensive (36 monthly samplings) and extensive (land use, pesticide applications, soil, vadose zone and aquifer characteristics) monitoring of aquifers ranging from a 1 hectare area of a sandy aquifer with GW table < 2 m bgl to a karst aquifer with GW > 10 m bgl.
- Development of mechanistic and semi-empirical tools dedicated to the spatialized modelling of pesticide contamination of GW, with i) operating links between root zone models and aquifer models, ii) consideration of non-equilibrium phenomena, and iii) incorporation of uncertainties associated with the field data and the results from transport models.
- Performance assessment of those tools using the data of the first 24 months monitoring for calibration, and assessing the predictive capacity (extrapolation step) by comparing predicted GW levels and pesticide concentrations with the values of the third hydrological cycle monitored.
- Socio-economic assessment of alternative scenarios including changes in land use and agricultural practices aiming at GW quality restoration or protection in a context of sustainable development.
Problems to be solved:
Pesticide concentrations above the 0.1 µg/L drinking water limit have been reported in many groundwaters (GW) used for drinking water supplies in Europe. Questions as why it happens and how it will evolve in the near and distant future can not be answered at the moment. Because the GW is used extensively for drinking water purposes, this is a problem of true European dimension.
PEGASE will focus on delivering performance-assessed tools to predict the possible evolution of GW contamination by pesticides at the aquifer scale and to assess the socio-economic implications of alternative scenarios aiming at GW quality restoration or protection. An improved knowledge of the relative importance of processes involved in pesticide transport to and in the GW of representative aquifers will benefit the harmonized regulatory procedure and eventually lead to reductions in environmental deterioration, benefiting the community at local, regional, national and international levels. The work to be conducted through PEGASE will complement European policy objectives by providing tools that will help in implementing the Member States policies across Europe by both legislators and stakeholders.
Expected Impacts:
A better understanding of how pesticide concentrations in GW are most likely to evolve over time (a key objective of PEGASE project) will enable a more cost-effective configuration of the treatment plants and result in a cheaper water supply for consumers, thereby yielding considerable benefits to end-users of GW resources. The knowledge provided by PEGASE will also help avoid very restrictive land practices to be recommanded or imposed that would not take account of site specific conditions (e.g. a particularly slow GW recharge, or long transit time of the water flux trough a very thick unsaturated zone). Finally, by identifying areas least at risk for GW pesticide contamination, PEGASE will enable the available financial resources to be allocated to the most vulnerable aeras, thus maximizing the improvement the society may expect from its limited financial and natural resources. All stakeholders will be associated with the socio-economic work in PEGASE, ensuring the choice of scenarios that may possibly be implemented and a true assessment of their direct and indirect environmental implications.
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