W3 Seminar: Complex fate of pesticides in dense vegetation buffers for mitigation of surface runoff pollution

Details

Presenter:
Rafael Muñoz-Carpena, Ph.D., Distinguished Professor, Department of Agricultural and Biological Engineering, UF 

Title:
Complex fate of pesticides in dense vegetation buffers for mitigation of surface runoff pollution: trapping, multi-compound biochemical degradation, and remobilization

Abstract:
The assessment of the effect of pesticide chemical interactions between parent and metabolites through surface and subsurface exposure pathways is critical in regulatory exposure assessments, as these breakdown products can sometimes be more toxic or persistent in the environment than the original chemical itself (Störmann, R. and B. Jastorff. 1993). Considerable attention has been given to the parent metabolite interactions in the context of subsurface pathways and the risk of groundwater pollution. However, surface transport interactions have received less attention as they are generally less predominant, although can be important in some instances.

Surface runoff mitigation of pesticides with vegetative filter strips (VFS) is receiving much interest in North America and the European Union after the introduction of quantitative mitigation in high-tier regulatory environmental risk analysis exposure assessments with the mechanistic model VFSMOD. However, currently this applies only to mitigation of single pesticides or single metabolites through the VFS (Tournebize, 2024). To address this limitation in this work we develop and test an efficient and flexible numerical approach to handle multispecies transformation kinetics in VFS for use in long-term simulations with VFSMOD, specifically degradation in the period between runoff events (rainfall hiatus) where degradation in the VFS surface can be affected by parent and metabolite interactions and environmental factors that control the surface residues and their remobilization on the next runoff event in the time series. Because of the regulatory use of VFSMOD in the context of high-tier environmental exposure assessment for pesticides (OECD, 2023; European Commission, 2024; Ritter et al., 2023), an important consideration when designing and implementing the new multispecies degradation algorithm is that it be transparent and portable with the open-source distribution of VFSMOD. The finite differences numerical algorithm matches closely the results the eigen value problem analytical solution. Because of its accuracy, flexibility to account for any number of species and multi-reactions is an accessible adjacency matrix form, and efficiency the proposed algorithm is also suitable for use in other existing models.