Approaches to improve the ecological risk assessment of pesticides in freshwaters

Doutoramento em Engenharia Agronómica - Instituto Superior de AgronomiaOne of the most important ways of improving agricultural production is the use of plant protection products. As this type of pesticides is used within the catchment area of freshwaters there is a potential for side-effects to occur in aquatic ecosystems. New challenges for risk assessment were addressed to achieve good chemical and ecological status in European water bodies. Site-specific and ecologically-based approaches were developed and applied to three important Portuguese river basins. Better criteria for the assessment of the ecological and chemical status of water bodies was provided by calculating groundwater threshold values for pesticides and by focusing on river basin specific pollutants. A list of priority pesticide mixtures that might pose aquatic risks was obtained by employing risk quotients based on concentration addition as a ‘screening level’ risk assessment of pesticide mixtures, and the multi-substance potentially affected fraction, representing a higher tier, with more practical usefulness and relevancy for risk management. For an integrated assessment of pesticide stress in freshwaters, and moving toward a more holistic approach, chemical analysis were used in combination with effect-based tools, in order to provide a link between chemical and ecological assessments. The results contribute for reducing the risks of pesticides in freshwatersFC