Assessment and management of pesticide pollution at a river basin level part I: Aquatic ecotoxicological quality indices.

During the last decade numerous monitoring programs have been conducted in order to assess pesticide pollution in catchments. This effort has led to the production of large, complex data sets of environmental results making the task of evaluation of the aquatic chemical status more difficult. Furthermore, the evaluation of the chemical status of the water ecosystems is one of the main aspects which should be considered in a River Basin Management Plan. In this study, two indices were developed in order to assess the combined pesticide ecotoxicity to aquatic non-target organisms, the Aquatic Quality Index of Short term Toxicity of Pesticides (AQI ShToxP) and the Aquatic Quality Index of Long term Toxicity of Pesticides (AQI LToxP). These indices were applied to the environmental results obtained from an intensive monitoring study of 302 pesticides in 102 stationary sampling stations located on the surface aquatic network of the Pinios River Basin, in Greece, in 2011 and 2012. The evaluation of the surface water quality was achieved by taking into consideration the frequency and the intensity of exposure of the aquatic organisms to pesticides above the respective ecotoxicological quality objectives such as the acute or chronic term predicted no-effect concentrations derived from risk assessment. Seventy-five pesticides, that have been previously identified as the River Basin Specific Pollutants of Pinios by an environmental and human risk hierarchy exercise, were assessed. It appears, from the implementation of the two indices, that the detected pesticides in the surface aquatic ecosystem of the Pinios River Basin exert significant pressure on the aquatic non-target organisms especially at the chronic effect level. The developed AQI ShToxP and AQI LToxP indices, as well as the proposed quality classification system could be valuable communication and interpretation tools for River Basin Management Plans that can contribute in the restoration of environmental health.