Considering degradation kinetics of pesticides in plant uptake models: proof of concept for potato

Abstract

BACKGROUND: Degradation kinetics of pesticides in plants are crucial for modeling mechanism-based pesticide residual concentrations. However, due to complex open-field conditions that involve multiple pesticide plant uptake and elimination processes, it is difficult to directly measure degradation kinetics of pesticides in plants. To address this limitation, we proposed a modeling approach for estimating degradation rate constants of pesticides in plants, using potato as a model crop. An operational tool was developed to backward-estimate degradation rate constants, and three pesticides were selected to perform example simulations. RESULTS:The simulation results of thiamethoxam indicated that the growth dynamics of the potato had a significant impact on the degradation kinetic estimates when the pesticide was applied during the early growth stage, as the size of the potato determined the uptake and elimination kinetics via diffusion. Using mepiquat, we demonstrated that geographical variations in weather conditions and soil properties led to significant differences in the dissipation kinetics in both potato plants and soil, which propagated the variability of the degradation rate constant. Simulation results of chlorpyrifos differed between two reported field studies, which is due to the effect of the vertical distribution of the residue concentration in the soil, which is not considered in the majority of recent studies. CONCLUSIONS: Our proposed approach is adaptable to plant growth dynamics, preharvest intervals, and multiple pesticide application events. In future research, it is expected that the proposed method will enable region-specific inputs to improve the estimation of the degradation kinetics of pesticides in plants.

Generic Model for Plant Uptake of Ionizable Pharmaceuticals and Personal Care Products

“…Biodegradation is of particular importance for mostly ionized chemicals due to their slow uptake into organisms (Carter et al, 2022). Because of the lack of data, degradation rates in plants are often neglected (Jacobsen et al, 2015; Li & Fantke, 2022), which leads to bioconcentration predictions at the upper end of measured ones (Polesel et al, 2015). The average of dissipation half‐life of loss data from plants collected by Fantke and Juraske (2013) was 7 days, which corresponds to the default growth dilution rate used for roots and corn (0.1 day −1 ) in the PPCP model.…”

Including the bioconcentration of pesticide metabolites in plant uptake modeling

“…From a risk and impact assessment perspective and due to data constraints, these models typically omit the biodegradation or biotransformation processes of pesticides within potato tissue. 47 However, our study deviates from this approach by incorporating such processes, as our primary focus centers on considering the generation of pesticide metabolites. Both soil and potatoes are involved in the transformation of the parent compound into metabolites.…”

Effect of biochar on soil microbial community, dissipation and uptake of chlorpyrifos and atrazine

“…Song et al (2023) in his review demonstrated that biochar has high adsorption potential and can accelerate the pesticide degradation of soil and mitigate its uptake in the plantings. Therefore, biochar application in pesticide-contaminated soil can be a good option for minimizing the risk associated with the consumption of contaminated agricultural produce (Li and Fantke 2023;Song et al 2023).…”