Fusarium Mycotoxins in Maize Field Soils: Method Validation and Implications for Sampling Strategy.

Area of Science:

• Environmental Science
• Analytical Chemistry
• Agricultural Science

Background:

• Mycotoxins, like trichothecenes and zearalenone, are increasingly recognized as environmental pollutants originating from Fusarium-infested fields.
• Soil contamination by mycotoxins from plant residues necessitates understanding their fate, effects, and transport.
• A critical gap exists in validated analytical methods for quantifying Fusarium toxins in soil matrices.

Purpose of the Study:

• To validate an analytical method for determining nivalenol (NIV), deoxynivalenol (DON), 15-acetyl-deoxynivalenol (15-AcDON), and zearalenone (ZEN) in agricultural soils at environmentally relevant concentrations.
• To assess the presence and levels of DON, NIV, and 15-AcDON in conventionally managed maize field soils.
• To investigate the spatial distribution of mycotoxins in soil.

Main Methods:

• Solid-liquid extraction assisted by ultrasonication using an acetonitrile:water solvent mixture.
• Quantification of mycotoxins using Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS).
• Method validation in five contrasting agricultural soils spiked at three concentration levels.

Main Results:

• The analytical method was successfully validated for NIV, DON, and 15-AcDON, with high mean recoveries (>93%) and low relative standard deviations (<10%).
• Zearalenone (ZEN) did not meet validation criteria.
• DON and NIV were detected in two of eight sampled maize fields, with concentrations ranging up to 19.4 ng g⁻¹ for DON and 2.2 ng g⁻¹ for NIV.
• Mycotoxin 'hot-spots' were found to be spatially restricted to small scales (<5 cm).

Conclusions:

• A robust analytical method for detecting key Fusarium mycotoxins in soil has been established.
• The presence of DON and NIV in maize field soils highlights environmental contamination.
• Findings on localized mycotoxin distribution have significant implications for developing effective soil monitoring strategies.