Sorption of the Veterinary Antimicrobials Sulfadimethoxine and Ormetoprim in Soil
- S. M. Sandersa,
- P. Srivastava *a,
- Y. Fengb,
- J. H. Danec,
- J. Basiled and
- M. O. Barnette
- a Biosystems Engineering, 200 Corley Bldg., Auburn Univ., Auburn, AL 36849
b Agronomy and Soils, 228 Funchess Hall, Auburn Univ., Auburn, AL 36849
c Agronomy and Soils, 258 Funchess Hall, Auburn Univ., Auburn, AL 36849
d Alabama Dep. of Agriculture and Industries, 1445 Federal Dr., Montgomery, AL 36107
e Civil Engineering, 208 Harbert Engineering Center, Auburn Univ., Auburn, AL 36849
Currently, limited research on the fate of antimicrobials in the environment exists, once they are discharged in human and animal wastes. Sorption of two antimicrobials, sulfadimethoxine (SDM) and ormetoprim (OMP), was investigated in two soils and sand using a series of batch experiments. Because OMP and SDM are often administered in combination, their sorption was also investigated in combination as co-solutes. The rate of SDM and OMP sorption was rapid over the first few hours of the experiments, which then slowed considerably after 16 to 68 h. OMP sorption was enhanced at high concentrations when in combination with SDM, with linear sorption coefficients ranging from 1.3 to 58.3 L·kg−1 in the single solute experiments and 4.96 to 89.7 L·kg−1 in the co-solute experiments. Sorption of OMP as a single solute seems to provide a better fit with the Freundlich equation, which became more linear (n approached 1) when SDM was present. Overall, SDM sorbed less than OMP in the two soils and sand. SDM linear sorption coefficients ranged from 0.4 to 25.8 L·kg−1 as a single solute and 2.5 to 22.1 L·kg−1 as a co-solute. Sorption of SDM becomes more nonlinear (n < 1) when SDM is present in combination with OMP. Overall, sorption of both antimicrobials increased in the selected soils and sand as the organic matter, clay content, and cation exchange capacity increased. These experiments indicate relatively low sorption of SDM and OMP in natural soils, making them a potential threat to surface and ground water.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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