Application of Environmental Potential Risk Indicator for Pesticides (EPRIP) to evaluate the environmental risks of Alternate Wetting and Drying irrigation for rice in northern Italy

Environmental Potential Risk Indicator for Pesticides (EPRIP) (Reus et al., 2002) was used to estimate the environmental impact of pesticides used in rice production with traditional and water-saving irrigation methods in the main Italian rice district (Lomellina, PV). EPRIP is based upon the Exposure Toxicity Ration (ETR) of the Predicted Environmental Concentration (PEC) (Padovani et al., 2004). A modified version of MED-Rice tool was used in order to evaluate PECs of seven pesticides into groundwater, surface water and paddy sediment. ETR and PEC were estimated at a local scale (field and surroundings), with short-term toxicological parameters (NOEC) and, therefore, reflecting a worst-case scenario, assuming that organisms are subjected to maximum exposure. ETR were then converted into risk points (RPs) accordingly to the following table (Trevisan et al., 2009): Range of ETR RISK POINT <0.01 1 0.01-0.1 2 0.1-1.0 3 1.0-10.0 4 >10.0 5 An experimental platform was set up in the main Italian rice district (Lomellina, PV), during the agricultural seasons 2019 and 2020, to compare different irrigation management options: in particular, wet seeding and traditional flooding (WFL) and wet seeding and alternated wetting and drying (AWD) for the agricultural season 2019 were considered in this paper. Two widely used pesticides (Clomazone, MCPA) were measured in irrigation water (inflow and outflow) and groundwater. Estimated RPs following Trevisan et al. (2009) were compared to measured RPs, based on the analysed Clomazone and MCPA concentrations in water samples collected from the experimental fields. Finally, the overall EPRIP indicator was based on RPs to evaluate the probability of the predicted concentration of contaminants in the environment to overcome a supposed threshold. The results are calculated considering the probability of not exceeding the Risk Point 3 (RP3) by assuming a Poisson cumulative function.