Influence of Soil Chemical Properties On Residual Antibiotics in Soil.

In the Republic of Korea, 1,458 Mg of 86 veterinary antibiotic active ingredients were used in 2006. The medicines ingested into livestock have been shown to be rapidly excreted via feces and urine and reach to soil and water environment through application of antibiotic-laden animal manure to agricultural land. The objective of the study was to investigate the influence of soil chemical characteristics on the residual veterinary antibiotics in soil. Three antibiotics; chlortetracycline (CTC), tylosin (TYL), and sulfamethazine (SMT) and four soils obtained from agricultural land in Korea were used in the study. Three antibiotics were detected in lettuce leaves with the highest value of 2.3, 26.4, and 46.0 ng g^-1 fresh weight, respectively, 69 days after transplanting. Lettuce grown in two soils with relatively high pH showed less CTC and TYL compared with two soils with low pH. Residual amounts of CTC and TYL in soil after lettuce harvesting were greater in soil with low pH than for relatively high pH soil. The decreasing residual amounts in soil with increasing soil pH was not observed for SMT. The result may imply that CTC and TYL bind to soil colloid particles by cation exchange while SMT interact with soil colloid through weak hydrophobic interaction.