Modelling the Fate of Pesticide Transformation Products From Plot to Catchment Scale—State of Knowledge and Future Challenges

Abstract

Transformation products (TP) of pesticides are found everywhere in the aquatic environment. Their dynamic formation and subsequent transport from agricultural fields to adjacent water bodies can be estimated by using environmental fate models, which is done in the registration process for plant protection products in the European Union. In this study, peer-reviewed applications of such models, the model complexity and their structure are documented and analysed. In total, 20 publications of 10 models – eight leaching models (GLEAMS, MACRO, RZWQM2, PEARL, PRZM, Pelmo, LEACHM, HYDRUS 1-D) and two catchment scale models (Zin-AgriTra, FRM) – were identified. The reviewed models greatly differ in their process complexity regarding the formation rate and the formation pathways of TPs.The major reason given for models failing to reproduce sampled TP concentrations in case studies was an erroneous substance transport, especially missing preferential flow simulation in soil. However, the contribution of TP formation processes to simulation uncertainty was not analysed at all in most of the studies. By comparing the structure of existing models, the state of knowledge on TP fate and requirements of TP fate assessment, the following recommendations were drawn: i) It is suggested that the models should be updated to reflect the current state of knowledge in process research, especially more complex transformation schemes and the formation of different TPs in different compartments, which was not included in most of the models. ii) Even though there are pesticide parent compound fate models at the catchment scale with a temporal resolution of one day, none of these models is able to simulate TP fate. Such models would enable scientists and authorities to estimate the environmental fate of TPs at the larger catchment scale or the regional scale. iii) To get over the assessment of the huge number of TPs formed in the environment, an integration of Quantitative Structure Properties Relationship models predicting TP fate characteristics, TP pathway prediction models and environmental fate models is suggested. This would allow for a largely automated and comprehensive assessment of the fate of a pesticide parent compound and all its TPs for regulatory purposes.

Numerical Prediction Uncertainty and Data Worth Analysis of Solute Transport in an Agricultural Clay Till Setting With Preferential Flow

“…Simulations were performed with MACRO 5.2 (Larsbo & Jarvis, 2003), a 1‐D model including preferential flow and solute transport. In the EU regulatory framework, the model is one of the recommended models for pesticide risk assessment (Gassmann, 2021). The model is a dual‐permeability model of flow and reactive solute transport considering different flow rates and solute concentrations in the micro‐ and macropore domains.…”

Model-based design of crop diversification through new field arrangements in spatially heterogeneous landscapes. A review

“…As these model categories are also often used interchangeably, all models are referred to as agroecosystem models. Very specialized models simulating only, for example, pesticide leaching (Bergstrom and Jarvis 1994;Gassmann 2021), soil erosion by water (Jarrah et al 2020;Raza et al 2021), or soil carbon sequestration (Falloon and Smith 2002;Foereid and Hogh-Jensen 2004;Jenkinson and Coleman 2008) were not considered in this review as they are too limited in the range of ESS that can be simulated. Other simulation approaches such as functionalstructural plant models (Vos et al 2010) were not included in this review as they typically exclude nutrient or water dynamics.…”

Advancing exposure assessment approaches to improve wildlife risk assessment

“…Geostatistical tools allow the characterization and prediction of spatial patterns of environmental contamination to assess exposure at the site investigation scale and over broader landscapes (Rate, 2021). Predictions about contaminant fate and spatial distribution over small and large scales are increasingly becoming a reality (Gassmann, 2021), even where detailed biomonitoring data are limited, such as pesticide use in developing countries (Tang et al, 2021).…”