Methodology to assess the ecotoxicological risk by pesticide pollution forsurface water ecosystems using models and GIS.

In the present work a methodology for ecotoxicological risk assessment by p esticide pollution for surface water ecosystems is presented. The approach requires the use of models and GIS. The study area is the potentially arabl e area of the Lombardia Region. For a number of selected agricultural chemi cals the PEC values are calculated using two different modeling approaches and referred to geographical units. Analysis of PEC and toxicological effec ts on representative organisms of the water ecosystem provides a TER evalua tion. The study of the exposed ecosystem is performed developing a Surface Water Sensibility Index (SWSI). The comparison between hazard index based o n TERs and SWSI generates an ecotoxicological risk index that assumes speci fic values for every considered water body and input scenario. The use of t he ecotoxicological risk cartography, produced by following the proposed me thodology, could provide decision makers with suggestions about territory m anagement related to the environmental impact of the agricultural activity.