Understanding the Sorption of Ionophoric Pharmaceuticals in a Treatment Wetland

Constructed treatment wetlands provide a cost-effective and efficient technique for removal of veterinary anticoccidials from agricultural wastewaters. A sorption study was conducted for three ionophoric antibiotics, monensin, salinomycin, and narasin, on sandy clay loam and sandy soils collected from two constructed wetlands. The effect of pH on sorption was also monitored. At the field pH of 6.8, sandy clay loam soil was found to have higher K-d (98.8-17.65 L kg(-1)) and Log K-oc (5.03-4.28 L kg(-1)) values for all three antibiotics compared to the sandy soil (K-d 38.24-8.52 L kg(-1) and Log K-oc 4.91-4.26 L kg(-1)). Narasin showed the highest K-d and K-oc, whereas the lowest were observed for monensin. The sorption of compounds manifested an inverse relation with pH, however the decrease in K-oc with increasing pH was considerably dampened due to specific solution characteristics of ionophores. Sorption factor will have the least and greatest effect in reducing mobility of the monensin and narasin compounds, respectively. The soil sterilization method of autoclaving was not found to be suitable for the soil and compounds evaluated.