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Time-dependent sorption of imidacloprid in two different soils
M Oi1
1Bayer AG, Crop Protection Business Group, Crop Protection Development, Institute for Metabolism Research and Residue Analysis, D-51368 Leverkusen, Germany.
Journal of Agricultural and Food Chemistry
|November 24, 1999
Summary
Imidacloprid sorption increases over time in soil, reducing its leaching potential. This study shows aged imidacloprid is less mobile, explaining its low field leaching despite high water solubility.
Area of Science:
- Environmental Chemistry
- Soil Science
- Agrochemicals
Background:
- Imidacloprid is a widely used insecticide with high water solubility.
- Understanding its environmental fate, particularly sorption and leaching, is crucial for risk assessment.
Purpose of the Study:
- To investigate the time-dependent sorption of imidacloprid in two German soils.
- To quantify the impact of soil aging on imidacloprid's sorption and leaching behavior.
Main Methods:
- Incubation of soil batches with imidacloprid for 100 days.
- Determination of desorbed and sorbed imidacloprid using CaCl(2) and organic solvent extractions.
- Verification of time-dependent sorption via column leaching experiments.
Main Results:
- Sorption coefficients (K(d) and K(oc)) for imidacloprid increased significantly (3.2-3.8 fold) with 100 days of soil aging.
- Column leaching experiments showed a twofold decrease in imidacloprid recovery in eluates from aged soil.
- Increased residence time in soil enhanced imidacloprid sorption, reducing its mobility.
Conclusions:
- Imidacloprid sorption is time-dependent, increasing with soil aging.
- Enhanced sorption significantly reduces the leaching potential of imidacloprid.
- These findings help explain the observed low field leaching of imidacloprid despite its high water solubility.