Long-term sulfamethazine leaching simulation in two different soils using the MACRO model.

Area of Science:

• Environmental Science
• Soil Science
• Water Quality

Background:

• Physically based models are used for pesticide and nutrient transport but lack validation for veterinary medicinal products.
• Veterinary medicines in soil pose risks, including water contamination, soil accumulation, resistant bacteria, and long-term leaching.

Purpose of the Study:

• To apply and validate the MACRO 5.2 model for simulating sulfamethazine (SMZ) transport over a decade.
• To assess the impact of calibration period length on SMZ leaching prediction accuracy and parameter uncertainty.

Main Methods:

• Utilized the physically based leaching model MACRO 5.2.
• Incorporated reversible kinetic and equilibrium adsorption with non-extractable residues.
• Employed two calibration periods (short-term vs. full period) to evaluate predictive uncertainties.
• Conducted temporal sensitivity analysis to understand parameter influence over time.

Main Results:

• Adequate simulation of SMZ leaching was achieved using the full 10-year calibration period, though with wide parameter ranges due to correlations.
• Short-term calibration led to predictions highly dependent on the calibration dataset's information content.
• Complex sorption parameters significantly influenced model output with increasing time, highlighting their importance for long-term predictions.

Conclusions:

• Reliable long-term simulation of veterinary medicinal product leaching necessitates considering parameters initially appearing insensitive.
• Temporal sensitivity analysis beyond the calibration period is crucial for identifying under-constrained parameters.
• This approach enhances confidence in leaching predictions, especially for periods lacking sampling data.