Unravelling Relationships between In Vivo Effects on Plants and Detected Pesticide Mixtures in Freshwaters of a South-European Agro-Ecosystem.

The multiple benefits agriculture provides to society depend on the long-term sustainable management of water resources, including the preservation of a good ecological and good chemical status of the water bodies. Presently, this good chemical status has not been reached in the majority of European river basins. Implemented monitoring strategies are targeted to identify the presence and magnitude of the ecological impacts that come from mixtures of chemicals but fail to give information on the causes of the ecosystem disruptions. This work aims to contribute to assessing the quality of surface waters used for irrigation in the LGVFX agricultural area (Central Portugal) by applying non-conventional in vivo phytotoxicity tests on three primary producers, a monocotyledon (Sorghum saccharatum) and two dicotyledons (Lepidium sativum and Sinapsis alba), complemented by chemical screening and mixture-risk modelling with component-based methods (summation of risk quotients) based on the classic concept of concentration addition (CA). Although inhibition percentages of the phytotoxicity parameter germination and root and shoot growth may be related to the presence of mixtures of pesticides, it was not possible to establish the fingerprinting of the detected compounds with the observed biological effects, mostly due to the large gap of ecotoxicological data on terrestrial plants exposed to contaminated water. In addition, pesticides can interact within the plant, leading to antagonism and synergism phenomena. [ABSTRACT FROM AUTHOR]