Pesticide Exposure Assessment in Rice Paddies in Europe

摘要

The increasing cost of monitoring and field studies have made mathematical modeling an indispensable part of pesticide registration process. Although, a uniform approach for proper model use has now been established in Europe this could not be used in rice due to the unique flooding conditions applied in rice cropping. Currently, in most cases predicted environmental concentrations (PECs)of pesticides applied in rice are calculated with a Tier 1 spreadsheet which was developed by the Med-Rice group. Recently, the SWAGW model was developed as a Tier 2 modeling tool, which is based on the Tier 1 spreadsheet but incorporates certain improvements including a more realistic partitioning of pesticide between water and soil. However, the use of more sophisticated models is essential in cases where refined modeling or application of mitigation strategies have to be applied. The RICEWQ model is the only validated model at present which can adequately predict the environmental fate of pesticides in rice paddies and provide PECs for GW and immediately adjacent SW systems. This model has been used in Europe for a realistic estimation of pesticide exposure at paddy-field scale. Rice is commonly cultivated in Europe in large river basins such as the Axios river basin in Greece or the National Park of Donana in Spain. Artificial and natural SW bodies are present in most of the rice- cultivated basins in Europe constituting a unique ecosystem. Therefore, it is relevant to consider pesticide risk assessment for rice at basin-scale level. The combined use of RICEWQ with the SW model RIVWQ allows a realistic estimation of PECs in SW bodies receiving water from treated paddies. This modeling tool has been already used for calculating exposure in rice-cultivated basins within the frame of basin-scale scenarios or in conjunction with spatial GIS data of specific rice cultivated zones.