[Leaching characteristics of sulfadiazine and sulfamethoxazole in soil column]

Leaching characteristics and influencing factors of the typical sulfa antibiotics-sulfadiazine and sulfamethoxazole were studied by soil column experiments. The results showed that the leaching rate increased and the residues of sulfa antibiotics in soil column decreased as the soil profile depth increased. The residual concentration of sulfa antibiotics in column filled with 0-20 cm profile soil was 2 times higher than that with 40-60 cm profile soil. The concentration of sulfa antibiotics in the leachate was higher, while the residual concentration in the soil column was lower under a higher leaching velocity. The concentration of sulfa antibiotics in the leachate was close to 500 microg.L-1 when the leaching velocity was 2 mL.min-1, while the concentration of sulfa antibiotics in the leachate was between 100-200 microg.L-1 when the leaching velocity was 1 and 1.5 mL.min-1. The concentrations of sulfa antibiotics in the leachate and soil column increased as the concentration of leaching solution increased. The concentration of sulfa antibiotics in the leachate was close to 0 microg.L-1 when the concentration of leaching solution was 250 microg.L-1 and 125 microg.L-1. When the concentration of leaching solution was 500 microg.L-1, the concentration of sulfa antibiotics in the leachate was close to 500 microg.L-1 and the residue concentration in the soil column was 2 to 3 times higher than that with lower concentration of leaching solution. The results in this research may provide a scientific basis for water irrigation with anibiotics.